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What is Amplitude Modulation? Complete Guide with Formula, Circuit Diagram & Practical Demo
Amplitude modulation (AM) was first introduced to enable long-range wireless audio communication, representing a major advancement over wireless telegraphy using spark-gap transmitters. Understanding what is amplitude modulation and how it works is fundamental for electronics engineering students and professionals working with radio frequency circuits. This comprehensive guide covers amplitude modulation theory, circuit design, practical implementation, and real-world testing results with oscilloscope demonstrations.
Speaking about modulation, in simple terms, it's the method used to impose the message signal on a carrier signal, which is then transmitted by antenna or wire. And demodulation is practically the exact opposite, where the message signal is extracted from the carrier wave and used. In this article, we are going to learn about modulation and more about amplitude modulation with a practical circuit implementation.
Table of Contents
- Modulation and Its Types
- Amplitude Modulation Theory
- How Does Amplitude Modulation Work? Step-by-Step Process
- Amplitude Modulation Waveform
- Amplitude Modulation Advantages and Disadvantages
- Amplitude Modulation Practical Demonstration
- Amplitude Modulation Circuit Diagram
- Amplitude Modulation FAQ - Common Questions Answered
- DIY Projects on Wireless Audio Transmission
Modulation and Its Types
Modulation is the process of adding information, like sound or data, to a high-frequency signal called a carrier wave so it can travel long distances or be sent more efficiently through wires or the air. Even though modulation itself looks simple, there are three main methods of modulation. They are:
Amplitude Modulation
Frequency Modulation
Phase Modulation
Below you can see a simple comparison chart that explains the basic differences between each type of modulation technique:
And remember that there are still more types of modulation available, like Pulse Amplitude Modulation (PAM), Pulse Width Modulation (PWM), Pulse Position Modulation (PPM), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Quadrature Amplitude Modulation (QAM), and more, as technology is getting improved day by day.
Amplitude Modulation Theory
Amplitude Modulation (AM) is a method of sending information, like voice or music, by changing the strength (amplitude) of a high-frequency carrier wave based on the input signal. It allows us to transmit audio over long distances using radio waves and forms the foundation of AM radio broadcasting systems.
So, you need to understand the meaning of amplitude first to understand AM clearly.
Amplitude of a Signal
In simple terms, amplitude is how strong or intense a wave is. It's plotted on a graph with time on the x-axis and amplitude on the y-axis. It's how loud the sound wave is, think of it as more volume, more sound, more amplitude.
It's usually measured in volts (V) for electrical signals, decibels (dB) for sound, or other units depending on the context.
Frequency of a Signal
Frequency is the number of times a wave with the same pattern repeats itself in one second. It tells us how fast a wave is vibrating. For example, a frequency of 50 Hz means the wave cycles 50 times every second.
It's usually measured in Hertz (Hz). Now let's take a deeper look at amplitude modulation and understand how it works step by step.
How Does Amplitude Modulation Work? Step-by-Step Process
Understanding how amplitude modulation works step by step is crucial for electronics engineers and students. The AM process involves three main stages: carrier wave generation, message signal preparation, and the modulation process itself. Here's how amplitude modulation works in practice:
Carrier Wave Generation: A high-frequency sine wave (typically 535 kHz to 1700 kHz for AM radio) is generated using an oscillator circuit like the ICL8038 or similar function generator.
Message Signal Input: The audio or data signal that contains the information to be transmitted is prepared and amplified to appropriate levels.
Modulation Process: The amplitude of the carrier wave is varied according to the instantaneous amplitude of the message signal using a modulator circuit.
Signal Combination: The modulated signal combines both the carrier frequency and the message information in a single waveform.
Transmission: The modulated signal is amplified and transmitted through an antenna for long-distance communication.
This step-by-step amplitude modulation process ensures that low-frequency audio signals can be transmitted over long distances by riding on high-frequency carrier waves.
Amplitude Modulation Waveform
Below, you can see the image that clearly illustrates the modulated wave along with the carrier wave and the message signal, showing how the AM waveform is formed.
The first wave shown is the carrier signal.
In the case of AM radio, the carrier signal will be a medium-frequency wave, typically from 535 kHz to 1700 kHz. This carrier signal is generally a pure sine wave, generated using a dedicated oscillator circuit.
The next wave is a simple example message signal for demonstration. In this message wave, there is no specific frequency or amplitude. It's all random, which is how a real message would be. But the only thing is that the frequency of the message signal will be lesser than the carrier wave frequency.
Now, in the third modulated signal, you can see that the amplitude of the upper side of the carrier signal looks exactly like the message signal. This is how amplitude modulation works. In general, this effect can be achieved easily using a single transistor, where the carrier wave is amplified with respect to the input message signal, just like that.
AM Signal Equation Explained
The amplitude modulation formula derivation starts with understanding how the message signal modifies the carrier amplitude. This AM signal equation explained below shows the mathematical relationship between carrier, message, and modulated signals:
s(t)=[Ac+m(t)]cos(2πfct)
Here,
s(t): Refers to the modulated signal as a function of time. Sometimes this modulated signal is also represented as v(t), which is more specific as a voltage signal and is mostly used in circuit analysis. In general, this modulated signal can be represented as s(t).
Ac: Refers to the amplitude of the carrier wave that is used.
fc: Refers to the frequency of the carrier wave.
m(t): Refers to the modulating message signal as a function of time.
Amplitude Modulation Formula Derivation Explained
To understand the amplitude modulation formula derivation, let's break down each component. The modulation index (m) is a crucial parameter that determines the depth of modulation and can be calculated as m = Am/Ac, where Am is the amplitude of the message signal and Ac is the carrier amplitude. For proper AM transmission without distortion, the modulation index should not exceed 1 (100% modulation).
The complete AM formula derivation shows that the modulated signal contains the original carrier frequency plus upper and lower sidebands that carry the actual information. This mathematical foundation is essential for understanding how AM modulator circuits work in practice.
Now let's get into a practical demonstration for clear understanding.
Amplitude Modulation Advantages and Disadvantages
When designing AM circuits, it's important to understand the advantages and disadvantages of amplitude modulation compared to other modulation techniques like FM and digital modulation:
Advantages of Amplitude Modulation:
Simple circuit design and low-cost implementation compared to FM circuits
Easy demodulation using simple diode detectors without complex circuitry
Good long-range transmission capabilities, especially during nighttime propagation
Minimal bandwidth requirements (bandwidth = 2 × message signal bandwidth)
Mature technology with well-established manufacturing processes
Compatible with low-cost receivers, making it accessible worldwide
Disadvantages of Amplitude Modulation:
Poor noise immunity compared to FM and digital modulation techniques
Lower power efficiency due to continuous carrier transmission (only 33% efficiency at 100% modulation)
Susceptible to atmospheric interference and electrical noise
Limited audio quality compared to modern FM and digital broadcasting
Fading effects during long-distance transmission can cause signal degradation
Amplitude Modulation Practical Demonstration
To demonstrate amplitude modulation, we came up with a simple circuit using minimal components that you can try yourself.
Components Required
To keep this demonstration simple, I will be using commonly available components that are easy to find. Here's the complete list for building your own AM modulator circuit:
Below are the key components involved in the modulation process.
BC547 - 1 (Common NPN Transistor)
7805 - 1 (5v Voltage Regulator)
Resistor - 470Ω - 3
Resistor - 100Ω - 1
Resistor 1KΩ - 1
Capacitor - 470nF-2
Capacitor - 10pF-1
Modules
These modules are added only to reduce the complexity of the circuit used for testing amplitude modulation. With these, two major complexities solved, the circuit for generating the carrier signal and the circuit for the microphone setup for the message signal.
ICL8083 - 1(For Carrier Signal Generation)
Bluetooth Audio Receiver - 1(For message signal input)
Amplitude Modulation Circuit Diagram
Before getting into the actual circuit diagram, let's understand the basic working behind the circuit diagram.
How to Build AM Modulator Circuit - Step by Step Guide
The image below shows the basic concept behind amplitude modulation. Depending on the real-time application, there might be some upgrades, but the core concept remains the same.
This amplitude modulation circuit design using BC547 transistor is perfect for students learning how to build AM modulator circuits. The circuit demonstrates the fundamental principle of AM generation and can be easily replicated on a breadboard. For beginners wondering how to make amplitude modulation circuit at home, this design uses commonly available components and provides clear, observable results on an oscilloscope.
The transistor acts like a variable amplifier controlled by two signals:
RF (Radio Frequency) input that comes from the oscillator (the medium-frequency carrier wave), and
Audio input that comes from a music source (like a computer, phone, or microphone).
The transistor works like an automatic volume control. As the audio signal gets louder, it makes the radio signal stronger. When the audio gets quieter, it makes the radio signal weaker.
This creates a modified radio signal where:
The frequency stays the same (like the radio station's channel),
The strength (amplitude) changes to match the message audio.
Any AM radio can detect these strength changes and convert them back into sound, simply by reversing the process.
Schematics of the AM Modulator
As you already know, to reduce the complexity, we are using separate modules for generating the carrier wave and feeding the message signal.
To clearly understand how the carrier wave is generated using the ICL8038, I recommend visiting the article: "How to Configure the ICL8038 to Generate a Sine Wave?" In our case, the only thing you need to know is that we power the ICL8038 module with 12V to ensure a higher frequency output.
In the above circuit diagram, you can clearly see the complete layout.
The generated sine wave (carrier wave) is fed into the base of the transistor with the help of a coupling capacitor. The base is also stabilized using two biasing resistors of 470Ω each.
For the message signal, we're using a simple, inexpensive Bluetooth audio receiver, the same module used in the project , Simple DIY Wireless Bluetooth Speakers using Audio Amplifier.
The audio output of the Bluetooth module is connected to the emitter of the transistor using a coupling capacitor. And that's it, most of the circuit is ready!
In practical AM transmitter circuits, a dedicated RF amplifier stage is added before the antenna. In simpler circuits, a small capacitor is used to block DC while allowing RF to pass, and sometimes a basic LC filter is used to reduce harmonics.
But in our case, since we're not using an AM receiver to test this setup and only want to observe it using an oscilloscope, we've added just a DC blocking capacitor at the output.
Powering the circuit is also important. I used a regulated power supply (RPS) to provide 12V to the entire circuit. This 12V powers both the ICL8038 module and the modulator transistor. A 7805 voltage regulator is used to provide 5V to the Bluetooth module.
Testing Our AM Modulator Setup
Testing was simple. I used my smartphone to send the message signal and an oscilloscope to verify the output and observe the amplitude modulation waveform in real time.
First, after connecting the breadboard to a 12V power supply, I checked for any faults.
I recommend you do the same, if the transistor is inserted with the wrong polarity, it may heat up quickly and its hFE (gain factor) could degrade over time.
Next, it was time to tune the carrier frequency on the ICL8038 module. I have set it to 380 kHz just as an example, you can set any high frequency of your choice for your AM modulator testing.
For precision, I used an oscilloscope to tune and verify the frequency.
I opened the Bluetooth settings on my smartphone and paired it with the Bluetooth audio receiver. If you don't have a Bluetooth module, you can also use a simple AUX cable from your phone to extract the audio signal for amplitude modulation testing.
Next, I opened a frequency generator app. You can use any app for sound or even music. But for clearer oscilloscope visuals and better amplitude modulation demonstration, I chose to generate a stationary sine wave.
Using the app, I generated a 22 kHz sine wave and connected the second probe of the oscilloscope to the circuit's output to observe the amplitude modulation results.
The oscilloscope display shows two important signals: the white trace (top) displays our 380 kHz carrier wave output from the AM modulator, while the yellow trace (bottom) shows the 22 kHz message signal from our phone app. The key observation is how the amplitude of the carrier wave (white) varies up and down following the exact pattern of the message signal (yellow), this varying envelope is amplitude modulation in action.
Notice how when the yellow message wave reaches its peak, the carrier amplitude becomes maximum, and when the message wave hits its lowest point, the carrier amplitude becomes minimum. This direct relationship proves our circuit is successfully impressing the audio information onto the high-frequency carrier wave. Please note that in the image above the carrier wave appears "inverted" due to our NPN transistor configuration, but this doesn't affect functionality.
This oscilloscope result confirms perfect amplitude modulation, the carrier frequency stays constant at 380 kHz while its amplitude varies according to our 22 kHz message signal. Any AM radio tuned to 380 kHz would detect these amplitude changes and convert them back into the original 22 kHz audio tone, demonstrating how AM radio communication works in practice.
Amplitude Modulation Circuit Troubleshooting Guide
When building your own AM modulator circuit, you might encounter some common issues. Here's a comprehensive troubleshooting guide for amplitude modulation circuits that will help you identify and fix problems quickly:
Common AM Circuit Problems and Solutions:
No Output Signal: Check power supply connections (ensure 12V is reaching ICL8038 and transistor), verify transistor orientation (BC547 pinout: CBE from left), and confirm all ground connections are secure
Distorted Modulation: Reduce message signal amplitude using volume control, check biasing resistor values (470Ω resistors), and ensure carrier frequency is much higher than audio frequency
Weak Carrier Signal: Verify ICL8038 module connections and power supply, adjust frequency control potentiometer, and check coupling capacitor connections
Overmodulation (Signal Clipping): Reduce audio input level from smartphone or Bluetooth module, check transistor biasing point, and ensure adequate power supply current
Poor Modulation Depth: Increase audio signal amplitude carefully, verify emitter coupling capacitor (470nF), and check transistor gain (hFE should be >100)
Oscilloscope Shows No Modulation: Ensure both carrier and audio signals are present, check probe ground connections, and verify oscilloscope trigger settings
AM Circuit Testing Tips:
Always test carrier signal first before adding audio input
Use low audio frequencies (100Hz-1kHz) for initial testing
Monitor transistor temperature - it shouldn't get hot during normal operation
Start with low modulation depth and gradually increase
Amplitude Modulation FAQ - Common Questions Answered
What is the difference between AM and FM modulation?
The main difference between AM and FM modulation is that AM (Amplitude Modulation) varies the amplitude of the carrier wave while keeping frequency constant, whereas FM (Frequency Modulation) varies the frequency while keeping amplitude constant. AM has simpler circuits and better long-range propagation but lower noise immunity compared to FM. AM radio operates in 535-1700 kHz band while FM radio uses 88-108 MHz band.
Why is amplitude modulation still used today?
Amplitude modulation is still used in AM radio broadcasting, aviation communications, and amateur radio because of its simplicity, excellent long-range propagation characteristics (especially at night), and the low cost of AM receivers. Many developing countries rely on AM radio for information dissemination due to its cost-effectiveness and simple receiver design.
What components are needed for a basic AM transmitter?
A basic AM transmitter requires an oscillator for carrier generation (like ICL8038), a modulator circuit (often using a transistor like BC547), an audio amplifier for the message signal, coupling capacitors, biasing resistors, and an RF amplifier stage before the antenna. Our demonstration uses BC547 transistor, ICL8038 module, resistors, capacitors, and basic passive components for a complete working AM modulator.
How do you calculate modulation index in amplitude modulation?
The modulation index (m) in amplitude modulation is calculated as m = Am/Ac, where Am is the amplitude of the message signal and Ac is the carrier signal amplitude. For undistorted transmission, the modulation index should not exceed 1 (100% modulation). Values above 1 cause overmodulation and signal distortion.
What is the bandwidth of an AM signal?
The bandwidth of an AM signal is twice the highest frequency of the modulating message signal. For example, if the audio signal has a maximum frequency of 5 kHz, the AM signal bandwidth will be 10 kHz. This is much narrower than FM signals, making AM more spectrum-efficient.
Can I build an AM radio transmitter legally?
Building AM transmitters for educational purposes is generally allowed, but transmitting signals over certain power levels requires licensing from your country's telecommunications authority. Always check local regulations before building and operating any radio transmitter. Low-power educational demonstrations are typically permitted.
DIY Projects on Wireless Audio Transmission
Discover practical implementations of wireless audio communication with these projects, ranging from ESP32-based internet radio to advanced wireless audio transfer using nRF24L01 modules, Li-Fi, and even LEDs. These amplitude modulation related projects will help you understand various wireless communication techniques.
Wireless Audio Transfer Using LASER Light
Learn how to transmit audio wirelessly using laser light with this simple and innovative DIY project. Explore the circuit, components, and working of laser-based audio communication similar to amplitude modulation principles.
Simple DIY Wireless Bluetooth Speakers using Audio Amplifier
Build your own wireless Bluetooth speaker with this easy DIY project. Learn about the circuit design, components used, and step-by-step instructions for audio playback using Bluetooth technology - the same module used in our AM demonstration.
Arduino based Audio Spy Bug using NRF24L01
Learn how to build an Arduino-based wireless audio spy bug using the NRF24L01 module. This project demonstrates real-time audio transmission for surveillance and remote listening applications using digital modulation techniques.
Audio Transfer using Li-Fi Technology
Explore how to transfer audio wirelessly using Li-Fi technology in this project. Learn how LED light is used to transmit sound signals without radio frequencies, demonstrating optical modulation techniques similar to amplitude modulation concepts.
Long Range Arduino Based Walkie Talkie using nRF24L01
Build a simple Arduino-based walkie-talkie using the NRF24L01 module to enable two-way wireless audio communication over short distances using digital modulation instead of traditional AM techniques.
How to use nRF24L01 module with Arduino?
Learn how to interface the nRF24L01 wireless transceiver module with Arduino Uno for reliable, low-power wireless communication in your projects using advanced digital modulation techniques.
ESP32 Based Internet Radio using MAX98357A I2S Amplifier Board
Build an ESP32-based internet radio using the MAX98357A I2S amplifier board to stream music over Wi-Fi with clear audio output and easy controls, representing modern alternatives to traditional AM radio broadcasting.
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Flip-Flop in Digital Electronics: Types, Truth Table, Logic Circuit and Practical Demonstration
A flip-flop in digital electronics is formally defined as "A bistable device with synchronous inputs that changes state only at specified transitions of a clock signal" (IEEE Standard 91/1984)
In general, flip-flops are fundamental components in digital electronics, capable of functioning as 1-bit memory storage devices. Unlike combinational logic gates, flip-flops have the unique ability to store state information (0 or 1, low or high) and maintain this stored state indefinitely until changed, all with synchronized operation using a clock signal.
If this sounds confusing right now, don't worry! By the end of this article, you'll understand everything clearly with simple explanations and real-world examples.
What is a flip-flop and how does it work?
A flip-flop is a fundamental digital circuit designed to store a single bit of data, serving as a critical memory element in electronics. It maintains one of two stable states (0 or 1) and transitions between them based on input signals and a clock pulse. There are many types of flip-flops, such as SR (Set-Reset), D (Data), JK, and T (Toggle) flip-flops and each has distinct input-output functionalities. We will get in-depth into each of them but for simple understanding, a D flip-flop captures the input value at the clock’s edge and holds it until the next cycle, ensuring precise data retention. Essential in sequential logic, flip-flops are integral to registers, counters, and memory units in microprocessors and digital systems, enabling synchronized and reliable operation.
Flip-flops operate by processing input signals through logic gates, with state changes synchronized by a clock signal to ensure stability and predictability. For example, in a D flip-flop, the data input is sampled only when the clock triggers, storing the value in a feedback loop until the next clock edge. Similarly, an SR flip-flop uses set and reset inputs to toggle states, while a JK flip-flop offers enhanced flexibility by resolving indeterminate states. This clock-driven mechanism prevents erratic behavior, making flip-flops ideal for applications requiring precise timing, such as in CPUs and memory modules. By maintaining and updating data in a controlled manner, flip-flops form the backbone of modern digital circuit design.
Difference between flip-flop and latch
When learning about flip-flops, it’s essential to mention latches as well—and there’s a good reason. The evolution of digital electronics typically follows this path:
Transistors → Logic Gates → Latches → Flip-Flops
This progression is why flip-flops and latches are often compared, even though they serve different purposes in circuit design.
Put simply, flip-flops are an advanced form of latches. Both can store a single bit of data, but,
Flip-flops are edge-triggered and change states based on a synchronous clock signal.
Latches are level-sensitive, meaning their output changes whenever the input signal is active.
The main challenge with using multiple latches is synchronization. Since latches respond immediately to input changes, a slight delay in signal arrival (like due to varying wire lengths) can lead to timing errors. In high-speed circuits, even nanosecond-level differences can cause problems.
Flip-flops solve this issue by ensuring all data changes happen only at the clock edge, making them perfect for synchronized operations.
With the above comparison chart, I’m sure you'll understand the difference between the two more clearly. With this, let's move on to the types of flip-flops, along with practical demonstrations.
Types of Flip-Flops in Digital Electronics
Although flip-flops evolved from latches, the Flip-Flop itself has some types to make it fit in certain applications. As I said, each single type was an evolution from another with a few improvements. So, without wasting any time, let's jump straight away into the types of flip-flops,
Here are the four primary types of Flip-Flops, which are
SR Flip-Flop
The SR (Set-Reset) Flip-Flop is the most basic and commonly used type of flip-flop, and it’s the foundation for more advanced types like D, JK, and T. It has two inputs: S (Set) and R (Reset). When S = 1, the output is set to 1. When R = 1, it resets to 0. If both S and R are 0, the output simply holds the previous state. But if S = R = 1, it enters an invalid state (also called the race around condition), which must be avoided in real-world circuits.
Unlike latches that respond to input levels, the SR Flip-Flop is edge-triggered, meaning it only reacts at the rising or falling edge of the clock signal. This makes it more reliable for timed operations in sequential circuits.
Also, keep in mind: most flip-flops (and logic ICs) are rising edge-triggered, while falling edge or dual-edge triggered types are rare and used in specific designs. That’s why we generally call them edge-triggered—because either edge could be used, depending on the application.
SR Flip-Flops are often used in basic control systems, like
Turning a relay ON or OFF with logic signals,
Simple memory storage where only a few states are needed, like in reset/start switches, push button debouncing.
Simple status flags.
Symbol & Truth Table of SR Flip-Flop
Above, you can see the symbol, along with the truth table. After undergoing some detailed research, we arrived at this truth table.
To make this simple to understand, I’ve used straightforward terms here:
No Change (S = R = 0): The flip-flop retains its previous state.
Set (S = 1, R = 0): Output Q becomes '1' (Set).
Reset (S = 0, R = 1): Output Q becomes '0' (Reset).
Invalid State (S = R = 1): Both outputs (Q and Q̅) may become '1', leading to instability. This condition is prohibited in most designs.
SR Flip-Flop Circuit Working
One of the simplest ways to implement an SR flip-flop is using NAND gates.
Above, you can see the basic circuit diagram of an SR flip-flop made using a combination of NAND gates. You can use any NAND IC, and the result will be the same. Here, we are using four NAND gates to construct the SR flip-flop.
The working is simply a combinational output of the logic gates. If you spend some time mapping the values for each individual logic gate, you should be able to understand it clearly.
According to the truth table, if we initially keep both the Set and Reset inputs LOW, the output will remain in its last state. I would like to add a note that this behavior might vary depending on the setup, especially between simulation and real hardware implementation.
If I make the Set pin HIGH while keeping the Reset pin LOW, that will eventually make Q HIGH and Q̅ LOW. Conversely, if the Reset pin is kept HIGH and the Set pin LOW, you will get LOW at Q and HIGH at Q̅.
Furthermore, if we keep both Set and Reset HIGH, the output will be unpredictable. In more technical terms, a race-around condition will occur, which should be avoided. To overcome that issue, the SR flip-flop was upgraded to a D flip-flop.
Practical Demonstration of SR Flip-Flop
To learn the SR flip-flop in a more practical way, you can refer to the article SR Flip-Flop with NAND Gates: Circuit, Truth Table and Working, which covers the SR flip-flop concept, its truth table, a list of components required, the circuit diagram with explanation, and the working of the SR flip-flop using NAND gates.
How to make SR flip-flop using NAND gates?
An SR (Set-Reset) flip-flop can be effectively built using NAND gates, as shown in the provided circuit diagram, which utilizes four 7400-series NAND gates. The 7400 chip contains four 2-input NAND gates, each with inputs (e.g., pins 1 and 2) and an output (pin 3). In this setup, two NAND gates form the core latch, while the other two act as input conditioners with the clock signal. The inputs S (Set) and R (Reset) are fed into the first pair of NAND gates alongside the clock signal, ensuring that state changes occur only on clock pulses. The outputs of these gates connect to the second pair, which are cross-coupled to create the latch, producing the Q and Q' (complementary) outputs. This configuration ensures the flip-flop stores a bit of data, setting Q to 1 when S is active or resetting Q to 0 when R is active, all synchronized by the clock.
In the diagram, the clock signal enables the flip-flop to update its state only when active (typically high). When the clock is high, the first NAND gate (top left) processes the S input, and the second NAND gate (bottom left) processes the R input. These outputs feed into the cross-coupled NAND gates (right side), which form the latch. If S is 1 and R is 0, the latch sets Q to 1 and Q' to 0; if R is 1 and S is 0, it resets Q to 0 and Q' to 1. When both S and R are 0, the latch holds its previous state, and both being 1 is an invalid condition for an SR flip-flop, as it leads to instability. The use of NAND gates ensures that the circuit operates reliably, with the clock providing precise control over when the flip-flop updates, making it ideal for applications in sequential logic circuits like registers and counters.
D Flip-Flop
The D Flip-Flop is actually an upgrade of the SR Flip-Flop, specifically designed to overcome its major limitation—the invalid state. Unlike the SR Flip-Flop, which requires two inputs (Set and Reset) and may enter an undefined condition when both are high, the D Flip-Flop simplifies the design by using just one input, the D (Data) input.
The operation is straightforward, whatever value is applied to the D input gets stored and reflected at the output Q, but only at the triggering edge of the clock signal (usually the rising edge).
Because it cleanly passes the input to the output in a controlled and predictable way, the D Flip-Flop is widely used in digital electronics, especially in applications like Data storage registers, Pipeline registers in CPUs, Buffering systems, Clocked data transfer circuits
Symbol & Truth Table of D Flip-Flop
Above, you can see the symbol along with the truth table for the D flip-flop. It is self-explanatory and simple to understand.
In Simple Terms:
At Clock Edge (↑), the flip-flop copies the D input and holds it until the next tick. That is, if we give HIGH, then Q will be HIGH, and vice versa.
Otherwise, the output stays the same as the previous state.
D Flip-Flop Circuit Working
Among many options for implementing a D flip-flop, I’ll go with the NAND gate version to keep it simple.
Below, you can see the circuit diagram of the D flip-flop, which might look similar to the SR flip-flop.
The only difference is that we have used an additional NAND gate as a NOT gate and combined the Set and Reset inputs into a single D input.
Here, as per the combinational logic circuit, Q will be equal to the D input value. If D is HIGH, Q will be HIGH, and Q̅ will be LOW. Similarly, when we provide LOW to the D input, Q will be LOW, and Q̅ will be HIGH. This all happens only at the rising or falling edge of the clock pulse.
If the clock pulse remains at the same logic level (either HIGH or LOW), then regardless of the D input, Q and Q̅ will remain the same as their last state.
Practical Uses of the D Flip-Flop
The D flip-flop is widely used in digital electronics for reliable data storage and synchronization. It forms the core of shift registers, enabling serial-to-parallel data conversion in communication systems. In microprocessors, D flip-flops are essential for building registers to hold temporary data during processing. They’re also used in counters, facilitating frequency division and event sequencing in clocks and timers. Additionally, D flip-flops ensure synchronized data transfer in memory units, preventing timing errors. Their ability to capture and hold data on clock edges makes them indispensable in sequential logic circuits.
If you want to explore the D Flip-Flop in a more practical way, check out the article D Type Flip-Flop: Circuit, Truth Table and Working. It covers the D Flip-Flop basics, truth table, logic gate representation, list of components required, circuit diagram with explanation, a practical demonstration, and even a video to help you understand better.
JK Flip-Flop
The JK Flip-Flop comes with a bit of history behind its name. The most common explanation is that it was just a naming choice used by an engineer in his documentation, maybe based on initials or just random letters that stuck around. Whatever the reason, this flip-flop became popular because it fixed a major issue in the SR Flip-Flop.
It has two inputs, J and K, which function similarly to the Set and Reset inputs in an SR flip-flop, but with a smart upgrade. When both J and K are held HIGH, instead of entering an invalid or unstable state (as seen in the SR flip-flop), the JK flip-flop simply toggles its output. This means if Q is currently LOW, it becomes HIGH, and if Q is HIGH, it becomes LOW. This automatic flipping behavior is what makes the JK flip-flop particularly useful and reliable in sequential circuits.
Because of this, the JK Flip-Flop is perfect for things like counters, digital clocks, and frequency dividers, where the circuit needs to switch states on its own in a clean and timed manner.
Symbol and Truth Table of the JK Flip-Flop
With the above symbol and truth table, you can understand the concept behind the JK flip-flop.
Just like the SR flip-flop, the combinations LOW-LOW, HIGH-LOW, and LOW-HIGH behave the same way. However, if both the J and K inputs are set to HIGH, you will observe a continuous state toggle with each clock pulse. So, let’s move on to the working part to understand it more clearly.
Working Explanation of JK Flip Flop
Like SR and D, it is also possible to implement a JK flip-flop using NAND gates. And that will be appropriate to learn the behavior easily.
Above, you can see the circuit diagram, but with a difference, it uses a 3-input NAND gate. So, it looks a little complex, but it’s actually quite easy.
If you're someone like me who tries to test the circuit using any simulation software like Proteus or Logisim, you might face difficulties in getting the proper output—I did too.
This flip-flop is difficult to simulate with its current combination. So, after some research, I found the circuit diagram below to work well for simulation. This was simulated using Proteus, and it replicates the same JK logic.
This is because, in real-world situations, there are pull-ups and pull-downs responsible for maintaining the active LOW or active HIGH state. But in simulation, it seems to lack such features. Adding them manually also didn’t work on my side.
With this, we can move to the explanation of the working.
Here, most of the logic is similar to the SR flip-flop, which means if you keep both inputs LOW, it will remain in the last state.
And if the J input is kept HIGH and the K is kept LOW, the output Q will be HIGH and Q̅ will be LOW.
Vice versa, if the J input is kept LOW and the K input is kept HIGH, the expected output will be Q LOW and Q̅ HIGH.
But in the case where both inputs are HIGH, the output will continuously toggle with each clock pulse.
Hope you got to know about the JK flip-flop. Now, in case you are looking to implement this in real-time hardware, we can still make it simple by using dedicated JK flip-flop ICs like 7473, which is often known as MC74HC73A, SN74LS73A, etc. By using this, it’s much easier to implement the JK flip-flop.
Simple explanation of JK flip-flop with Circuit
To explore the representation of JK Flip-Flop using logic gates, a list of components required, the circuit diagram with explanation, and a practical demonstration with working, you can check out the article: JK Flip-Flop: Circuit, Truth Table and Working.
T Flip-Flop
The T Flip-Flop, also known as the Toggle Flip-Flop, is actually a simplified version of the JK Flip-Flop. In fact, it’s like taking a JK Flip-Flop and tying both the J and K inputs together. So instead of two inputs, it has just one—called T (for Toggle).
The working is super simple,
When T = 0, nothing happens. The output stays the same.
When T = 1, the output continuously toggles. IE: If Q = 0, it becomes 1; if Q = 1, it becomes 0, and this cycle repeats on each Clock pulse.
That’s it. This flip-flop is all about flipping the state when told to do so.
Because of its simplicity, the T Flip-Flop is commonly used in binary counters, toggle switches, and control circuits, especially where you want to alternate states with each clock pulse. It’s a neat little component that turns a basic input into reliable, timed output transitions.
Symbol & Truth Table of the T Flip-Flop
Above you can see the symbol and the truth table for the T Flip-Flop. The T Flip-Flop has just one input, T, and it works based on clock edges—usually the rising edge.
If T is set LOW, the output doesn’t change, no matter how many clock pulses come in. It just holds the previous state.
But when T is set HIGH, the magic happens—on every rising edge of the clock, the output continuously toggles. That means if the current output (Q) is LOW, it becomes HIGH, and if it’s HIGH, it becomes LOW.
T Flip-Flop Circuit Working
As you know, this T Flip-Flop is the extended version of the JK Flip-Flop. Simply tying the J and K inputs of the JK Flip-Flop to the T input makes the T Flip-Flop. Below you can see the circuit diagram of the T Flip-Flop.
As we already discussed in the JK working section, simulating the same is not easy. I tried different combinations, but finally, it was only possible using the direct JK Flip-Flop IC. So, if you need to do a simulation, you can check it out using the 7473 JK Flip-Flop IC.
Above you can see the general working of the T Flip-Flop’s combinational logic circuit. As we already discussed, when T is LOW (0), the output stays in its last state, no matter how many clock pulses you give. But when T is HIGH (1), the output toggles on every rising edge of the clock—so if Q was 0, it becomes 1, and if it was 1, it becomes 0.
Just like the JK Flip-Flop, we can use the 7473 IC for demonstrating the T Flip-Flop.
Practical Demonstration of the Toggle Flip-Flop
To dive deeper into the T Flip-Flop, check out the article T Flip-Flop: Circuit, Truth Table and Working. It explains the logic diagram, truth table, and excitation table, compares D and T flip-flops, shows how to convert between D, T, and JK flip-flops, lists the components required, and includes the circuit diagram, working explanation, a practical demo, and even a video to help you understand it clearly.
Comparison between the types of flip-flop
Hope you understand all the types of Flip-Flop Individually in the above sections. Now lets go through a direct brief comparison between each type of flip-flop.
Remember,
SR Flip-Flop is basic but can become unstable when both inputs are HIGH.
D Flip-Flop is ideal for precise data latching, what goes in comes out on clock.
JK Flip-Flop fixes SR's flaws and adds a toggle feature, great for counters.
T Flip-Flop is perfect for flipping states, used widely in frequency division.
Projects on Flip-Flop
These projects offer practical insights into flip-flop applications in digital electronics, helping to understand their use in memory storage, timing circuits, counters, and data synchronization in simple systems.
SR Flip-Flop with NAND Gates: Circuit, Truth Table and Working
Learn how to design an SR flip-flop circuit using NAND gates. This article covers the circuit diagram, working principles, and truth table for a better understanding of SR flip-flops in digital electronics.
T Flip-Flop: Circuit, Truth Table and Working
Learn about T Flip-Flop circuits, including their truth table, working principles, and applications. Explore how this type of flip-flop is used in digital electronics for toggling operations and building counters, with practical circuit examples and clear explanations.
JK Flip-Flop: Circuit, Truth Table and Working
Explore the JK Flip-Flop, its truth table, working principles, and circuit design. Explore its applications in digital electronics, including its use in counters and toggle circuits. Understand how this versatile flip-flop functions with practical examples and clear explanations.
D Type Flip-Flop: Circuit, Truth Table and Working
Understand how the D Flip-Flop works, including its circuit design, truth table, and practical uses. Learn its importance in memory storage and data synchronization with simple explanations and diagrams.
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Wireless Audio Transfer Using LASER Light
In this article, we are going to discuss how to transfer audio through laser light. This is a fun little project and the concept is similar to what we see in fiber optics cable, we will use a laser light to send data from one point to another. To be particular, in this project here we are going to transfer our voice from one point to another by shining a laser light on a solar panel. This is made possible by Light Fidelity or (Li-Fi) in short, for those who are new Li-Fi is a technology in which data can be transferred using light, in our case we sending our voice as data and using Laser as light source.
The highlight of this project is its simplicity, you can easily build this over a weekend with commonly available components. If you are interested in Li-Fi you can also check our our Li-Fi Text communication and Li-Fi audio transfer projects.
So, without further delay, let’s dive into building the project.
How to transfer Audio using Laser Light?
Transmitting Audio via Laser light is simple than it sounds. On the transmitter side we have a microphone which converts our voice into electrical signals, this signal then amplified using an audio amplifier and the output of this amplifier is directly connected to a LASER diode. This light is then pointed towards the solar panel on our received circuit. Agian, on the receiver side the solar panel is connected as audio input for another audio amplifier which amplifies these signals and plays it on a speaker. All of this works because of the ability of light to carry data.
Transmitter Side
Audio to Electrical Signal:
Our aim is to transfer the live audio signal, so in that case, we need some sort of microphone to convert the audio signal to an electrical signal. Actually, speaking, there comes a little bit of a complex circuit to achieve a perfect output. So, to make it simple, we are going to use the MAX4466 Microphone Amplifier Module, you can check out the link if you want to know more about this microphone module.
Above, you can see the GIF video representing the working of the MAX4466 Microphone Amplifier Module. Now we have the electrical signal that needs to be transmitted over the laser.
Electric Signal to Laser Beam:
In the above process, we have received the electrical signal. Now this electrical signal is used to drive the laser light beam. It can be done using multiple ways, like using some analog circuits (i.e., switching MOSFET). But to make it simple and more effective, we are using a Mini 5V Audio Amplifier Module based on PAM8403, as you can see in the image below.
The reason behind choosing this is simple. It works in the 5V range, so it can be easily integrated with the MAX4466 Microphone Amplifier Module. It also has an inbuilt potentiometer to adjust the amplitude of the output, and more importantly, it is more affordable. You can use whatever amplifier board you have or even create your own circuits to do the job right. Still, I suggest using the audio amplifier board for better output and hassle-free work. We have previously used the PAM8403 to also build a simple DIY Bluetooth speaker, you can check that out if you are intrested.
Now, a laser diode can be connected to the output of the PAM8403 module.
Above, you can see the laser diode we are using. If you would like to reduce the current fed to the laser, you can use a resistor of minimum value. Here, the laser we are using has a built-in 30-ohm resistor in series with the power input. If you feel like reducing the power, you can do so by adding an extra resistor in series or even adjusting the potentiometer in the PAM8403 module.
Receiver Side
Laser Light to Electrical Signal:
As in the last step we have already completed the transmitter side, here we go with the receiver side. So the primary process is to convert the audio signal from the laser light beam to its original state of electrical signal. Here, generally, we can use any light-based sensor (i.e., LDR, photodiode, etc.) to do the job right, but those with smaller reception areas are quite tough to use. However, they are not unusable; you can even use them. But here in this project, I am going to use a larger array of photodiodes, which is also known as the solar panel.
I am going to use a small toy solar panel. Despite its minimal power output, it is more than enough for our project. So, by using this solar panel, we are going to convert the laser beam to an electrical signal.
Electrical Signal to Speaker:
The electrical signal from the solar panel cannot be directly fed to the speaker due to its low power output. Even with a larger solar panel, the small point of light hitting the panel doesn't make a significant change in the output; we will only get a higher DC voltage with a larger panel. However, we need an analog voltage.
To solve this issue, I am going to use the same amplifier module that we used on the transmitter side so that the output electrical signal can be effectively amplified and passed to the speaker.
Regarding the speaker, you can use any speaker compatible with your amplifier module. I am using a 4-ohm, 10-watt speaker, as shown in the image above.
Therefore, we have successfully completed the theory part. I hope you all understand the main concept behind choosing the components and the workings of the project. So, let’s move on to the hardware part of the project.
Components Required for Wireless Audio Transfer Using Laser Light Project
Below is the list of required components to build the Wireless Audio Transfer using a laser light project. Some components may have alternates. To learn more about that, read the “Concept of Audio Transfer Via Laser - Explanation” available above.
Solar Panel - x1
Laser Diode - x1
Resistor (30 ohms) - x1
Potentiometer (100k) - x1
Speaker (4 ohms, 10W) - x1
PAM8403 Audio Amplifier Module with Potentiometer - x2
9V Battery - x2
BreadBoard - x2
Jumper Wires - Required Quantity
Circuit Diagram of Wireless Audio Transfer Project Using Laser Light
Here this project is built by keeping in mind that to make it easy and use only Minimal components. So, as an outcome, the circuit is simple for Everyone to understand and recreate.
Transmitter Part:
Here you can see the Schematic of the transmitter part. Those connections are self-explanatory.
We can split the schematic into two parts: The power and Transmitter Section.
Power Section:
Here, the power source selected is a 9V battery. Since the rest of the circuit operates at 5V, I am using a 7805 5V Linear Voltage Regulator to effectively convert 9V to 5V.
Transmitter Section:
In this section, only four components are being used.
Both the MAX4466 and PAM8403 modules are powered using the 5V output from the voltage regulator. The output of the MAX4466 Microphone Amplifier Module is connected directly to the PAM8403 Audio Amplifier Module.
The PAM8403 supports 2 channels. You can use one channel alone or use both channels as I have. However, we are going to drive only one laser. The laser's positive and negative terminals are connected in parallel with one of the channels. While connecting, I have mentioned using a 30-ohm resistor in series. This is for limiting the current flowing through the laser diode. If you are using the same laser diode as me, this resistor is not needed as it already has a 30-ohm resistor connected internally.
Receiver Part:
Below you can see the schematic of the receiver part. You might notice a similar power section here like the transmitter part, as our requirement is still the same. We are powering the system using 5V.
Receiver Section:
Here, the solar panel’s negative side is grounded, and the positive side is connected to the input of the PAM8403 Audio Amplifier Module. Like the transmitter, I kept both input channels connected. An extra step is applying the bias voltage to the input using a potentiometer, which sets the DC offset to the input of the amplifier. Finally, a speaker is connected to the output of the PAM8403 amplifier module.
That completes our circuit. Next, let us move on to the assembling part.
Building the Circuit
Let's build the circuit according to our schematic. I am using a breadboard to assemble all the components.
Above, you can see the assembled image of the transmitter with its parts marked for your reference. The laser diode is directly soldered to a 2x2 Berg strip connector, allowing it to be easily fixed to the breadboard. Similarly, the battery connector is also fitted with a Berg strip for easy breadboard integration.
In this transmitter, there are two configurable areas. One is the gain adjustment in the MAX4466 Microphone Amplifier Module, which controls the sensitivity of the microphone. The other is the amplitude adjustment in the PAM8403 module, which controls the output power to the laser diode. These configurable options allow for precise signal control.
Above, you can see the assembled image of the receiver. Parts like the speaker, solar panel, and battery are connected to the breadboard using Berg male strips, which I have soldered to the wires and fixed to the breadboard.
Like the transmitter, the receiver also has two configurable options. There is a potentiometer connected to the input of the PAM8403 module, which is used to set the DC offset to the input signal. The PAM8403 module itself has a potentiometer to adjust the amplitude of the signal going to the speaker, effectively allowing volume adjustment.
With this, we have completed building the circuit as per the schematic diagram. Next, Working demonstration.
Working Demonstration of the Wireless Audio Transfer Project
After successfully assembling the components, we began testing the project. It works well both indoors and outdoors, regardless of the conditions. The range of the wireless transfer is impressive, as the intensity of the laser does not diminish significantly under clear weather conditions. As long as the laser beam hits the solar panel, the audio is transferred seamlessly. We also tested the setup from multiple angles and encountered no issues.
The image above was taken while testing the setup outdoors. Unlike other projects, I did not include any GIFs to show the working process, but we have made a video that you can watch below. The video provides a complete demonstration and explanation of the project.
Some of the Improvement Ideas & Additional Possibilities for this Wireless Audio Transfer Project
These are some of my ideas for extending this project, which you can give a try.
Improvement ideas:
Use a more sensitive photodetector instead of a toy solar panel, such as an avalanche photodiode (APD), to improve the reception quality and range.
Implement a focusing lens system to concentrate the laser light on a smaller, more sensitive area of the photodetector.
Introduce noise reduction techniques and filters to improve the audio signal quality.
Some sort of Automatic Alignment System to ensure optimal signal transmission even with movement or misalignment.
Additional Possibilities:
Expand the project to support bidirectional communication by incorporating a similar setup on both ends, allowing two-way audio transmission.
Adapt the system to transmit not only audio but also other types of data, such as digital signals for internet communication, by incorporating appropriate modulation techniques.
Experiment with different laser wavelengths and power levels to extend the effective range of communication, ensuring long-distance transmission capabilities.
Design a compact, battery-operated version of the system for portability, making it suitable for mobile and field applications.
Frequently Asked Questions
1) Can we use laser in Li-Fi?
Of course, you can use lasers in a Li-Fi system. Practically, any light source along with its sensor can be utilized to create a Li-Fi system.
2) Is LiFi Better than Wi-Fi?
Determining whether Li-Fi is better than Wi-Fi depends on various factors. Both have their own pros and cons. For a detailed explanation, visit our article LiFi vs WiFi.
3) Is LiFi Safe for Humans?
Yes, LiFi (Light Fidelity) is generally considered safe for humans due to its Non-Ionizing Radiation, Low Power Levels, Limited Range, etc. Overall, LiFi is a promising and safe technology for wireless communication, offering a secure and efficient alternative to traditional radio frequency-based systems.
4) Advantages and Disadvantages of LiFi?
Advantages of Li-Fi
High-Speed Data Transfer: Li-Fi provides exceptionally fast data transfer rates, often surpassing those of traditional Wi-Fi, by utilizing visible light.
Enhanced Security: Since light cannot pass through walls, Li-Fi offers better security against unauthorized access compared to radio frequency systems.
No Radio Frequency Interference: Li-Fi avoids issues related to radio frequency interference, making it suitable for environments sensitive to such interference.
Reduced Latency: Li-Fi can achieve lower latency compared to Wi-Fi, benefiting applications requiring real-time communication and streaming.
Energy Efficiency: Li-Fi can make use of existing LED lighting systems, which are energy-efficient and help lower overall energy consumption.
Disadvantages of Li-Fi
Line-of-Sight Requirement: Li-Fi needs a direct line of sight between the transmitter and receiver, which can limit its range and flexibility.
Limited Range: The operational range of Li-Fi is shorter than that of Wi-Fi due to its reliance on visible light.
Indoor Use Only: Li-Fi is mainly effective in indoor settings where light can be easily managed and controlled.
Light Obstruction: Any blockage or interruption in the light path can disrupt the communication, impacting reliability.
Cost and Infrastructure: Implementing Li-Fi may require higher initial costs and changes to existing infrastructure, such as upgrading to suitable lighting systems.
5) What is LiFi Used For?
Li-Fi (Light Fidelity) provides high-speed wireless communication by using visible light, ultraviolet, and infrared radiation for data transmission. It is employed in various settings, such as secure environments where radio frequency (RF) signals are restricted, including military and healthcare facilities. Li-Fi offers fast internet access and can be integrated with LED lighting systems to deliver both illumination and data transfer. It is advantageous in areas with high RF interference and is used to enhance applications like augmented reality (AR) and virtual reality (VR) with its superior bandwidth and low latency.
6) What is SLD Laser LiFi?
SLD (Surface Light Emitting Diode) laser Li-Fi refers to a technology that utilizes surface-emitting laser diodes to facilitate communication via light. Unlike traditional LEDs that emit light from a single point, SLDs distribute light over a larger surface area, which enhances the efficiency and performance of Li-Fi systems. In SLD laser Li-Fi setups, these laser diodes enable high-speed, high-bandwidth communication using visible light, offering faster data transfer rates compared to conventional LED-based systems. This technology is beneficial for applications demanding rapid data transmission and reliable performance, such as in urban environments and industrial contexts.
Projects in Similar Relm
1) Li-Fi-based Text Communication between Two Arduino
Demonstration of Li-Fi communication using two Arduino boards: text data is transmitted from an LED and a 4x4 keypad and decoded on the receiver side using an LDR. This showcases Li-Fi's ability to facilitate high-speed, optical data transfer.
2) Audio Transfer using Li-Fi Technology
In this project, we’ll build a circuit to transfer audio data using Li-Fi technology.
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How does a Two Way Switch Work - Wiring Connection and Demonstration
One of the simple yet interesting connection diagrams that young engineers learn in their lab is the staircase lighting setup. Perhaps most of us might have already used it without paying much attention to how it works. Staircase lighting at home or at any other place, for that matter, is normally done with something called a two-way switch.
Now, there are many different types of switches in the market, and a few of them can be directly used for a two-way connection without any special wiring connections. But in this tutorial, we will show you how to make a two-way switch wiring with normal household switches. A two-way switching connection means you can control electrical equipment, like a bulb, with two switches placed at different locations, generally used in staircases.
A two-way switch can be operated from either switch independently, meaning whatever the position of the other switch (ON/OFF), you can control the light with the other switch. There are two methods of making a two-way switching connection: one is the 2-wire control, and the other is the 3-wire control. We have explained both methods below, and both methods are demonstrated in the video given at the end of this article.
Two Way Switch?
From Starting We are using the word Two Way switch. Some might know, some not. Let’s see that in brief.
So, technically a two-way switch is known as Single Pole Double Through (SPDT) Switch. Below You can see Some of the Types available in the market.
Some are used in DIY Projects and Some are Used in Electrical. The following concept is Applicable to all types of applications from Small DIY Projects to Complex Electrical Wiring Works.
Required Components for Two-Way Switch Connection Experiment
2-way switches x 2
Bulb x 1
AC supply x 1
Connecting wires
Connecting Two-Way Switch in Two Wire Configuration
This is the first method to make a 2-way switching connection, this is the old method. If you are going to install a new one, then go for three wire control methods.
As you see in the 2-way switch diagram below, you will find that the phase/live is connected with the common of the first 2-way switch. PIN1 & PIN2 of the first switch are connected with the PIN1 & PIN2 of the second switch respectively. One end of the bulb is connected with the Common Terminal of the second switch and another end of the Bulb is connected with the Neutral line of the AC power supply.
Note: In the 2-wire control method when switches are in an opposite state the light will be in OFF state as shown in the circuit below:
The condition of getting Output in ON condition is the same as the Ex-nor gate truth table which is given below:
| Switch 1 (SW1) | Switch 2 (SW2) | Lamp state (L1) |
| OFF | OFF | ON |
| ON | OFF | OFF |
| ON | ON | ON |
| OFF | ON | OFF |
Connecting Two-Way Switch in Three-Wire Configuration
This is the new method to make a 2-way switch connection and it is slightly different from the two-wire control method. This method is commonly used nowadays as it is efficient than the Two-Wire control system.
As you can see in the Schematic Diagram of 2-way switch circuit below, the common of both the switches are short-circuited. PIN1 of both the switches are connected with the phase or live wire and PIN2 of both the switches are connected with the one end of the lamp. The other end of the Lamp is connected with the Neutral line of AC power supply.
Note: In the 3-wire control method when switches are in the same state the light will be in OFF state as shown in the circuit below:
The condition of getting Output in ON condition is the same as the Ex-or gate truth table which is given below:
| Switch 1 (SW1) | Switch 2 (SW2) | Lamp state (L1) |
| OFF | OFF | OFF |
| ON | OFF | ON |
| ON | ON | OFF |
| OFF | ON | ON |
Advantages and Disadvantages of these Configurations
Advantages:
Allows control of any appliance from two different areas, regardless of the distance between them. Ideal for locations like staircases, large rooms, and bedrooms where control from multiple points is beneficial. Reduces the need to walk across dark areas to turn lights on or off, enhancing safety.
Disadvantages:
-Increased Wiring: Requires a significant amount of wiring, which can be more complex and costly to install. Diagnosing and fixing issues can be more challenging due to the additional wiring and switch points.
Applications of Two-Way Switch:
Staircases: For controlling lights from both the top and bottom of the stairs.
Erroneous Tripping of Safety/Circuit Protection Equipment: Helps in resetting tripped circuits from different locations.
Large Rooms with Multiple Entry/Exit Gates: Allows for convenient control of lighting or other equipment from different entrances.
Controlling AC Appliances (like fans or lights): Can be controlled from two places, such as the entry and exit points of a room.
Bedrooms: For controlling lights or fans from near the bed or while entering the room, providing convenience and flexibility.
Video
Comments
It's a age old logic but still a mesmerizing thing to people who doesn't belong to this domain. Thanks for explaining it so clearly.
In the electrician's trade, the two switch location load control is termed a '3-way' system. The wiring schematic conforming to the adopted International Code Council requires a different physical configuration for safety compliance than what is demonstrated in this article.
Thankyou so much.
.I like it
Thank you for this acticle. You solved a problem for me.
Does anyone know how to do this with an led mech like the clipsal 30PBL? I'd like the mech led off when that switch is powering the light.
nice tutorial of new way of two way two place light control connecting but there is one isuue compared to old way - one additional wire leading in parallel to light. this is redundancy every one want to avoid
It is a good explaination thanks
The three wire versions only virtue is having both switches the same way up.
With the two wire version you just turn one switch through 180 degrees and it amounts to the same!
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A Simple Automatic Plant Watering System without Microcontroller
Nowadays, many people are turning towards green solutions to lead healthier lives. Efforts are being made to grow plants, which contribute to maintaining the stability of nature. The key challenge in growing plants is maintenance, particularly ensuring they receive adequate watering. Despite our best intentions, we may forget to water our plants at times. To address this, we have developed a very simple automatic plant watering system without Arduino. The idea is to use minimal components and reduce complexity so that everyone can easily build it. It's an ideal option for anyone who is trying to automatically water their potted plants during a vacation
Let’s see, how we can do that!
Features of Automatic Plant Watering System Project:
Based on commonly used BC547.
Easy to build.
No need for coding.
Low-cost design.
Easy availability of components.
Has a built-in adjustable delay function.
Components Required to Build Self Plant Watering System:
Required Components are listed below to build the simple Automatic plant watering system,
Soil Moisture Sensor - x1
BC547 - x3
Electrolytic Capacitor - 680uf - x1
Resistor -
○ 10k-x1
○ 1k-x1
○ 500E-x1
100k Ohm Potentiometer - x1
Bread Board - x1
Mini Water Pump (3-6v) - x1
Mini Water Tube suitable for pump- Required Length.
5V Power Source - Any
Circuit Diagram Indoor Automatic Plant Watering System:
Below is the circuit diagram of the Automatic plant watering system, as you can see this circuit diagram was so simple and beginner-friendly. If you are not comfortable using components like transistors and resistors you can try check out our alternate project which uses Arduino for Automatic Plan watering system.
Here, the soil moisture sensor is the main component to detect the presence of water in the soil. You can visit our Well written article to learn how the soil moisture sensor works. You may think that with the addition of a single transistor to switch the motor, our circuit can be completed, but yeh here are still two transistors used. It looks simple at the beginning but if you think carefully there is the problem that if the motor is turned on for a very short duration it might trigger the motor more often and there will be a need for proper watering of the plant.
So, to solve this issue we are utilizing the simplest timer circuit known as RC Timer Which can be seen below. Depending on the value of the resistor and capacitor we can make the time delay of up to a few seconds. As an advantage, we added a potentiometer to make this time delay adjustable.
Next, you can understand that the Transistor Q1 is used to discharge the capacitor whenever the HIGH signal is received from the Soil Moisture sensor. The output from the RC Timer is Connected to the Q2, which here works as an inverter. So therefore, I am using Q3 to drive the motor.
You may confuse that Q2 itself can drive the motor instead of being an inverter. Yeah, of course, it can be used to drive a motor if your sensor provides Low for Dryness. But Most of the sensors out there will provide High for Dryness and Low for Wetness. You can refer to the table provided below for a brief understanding.
| Sensor Input | Sensor Output | Inverter Requirement | Expected Water Pump State |
| Wetness | HIGH | YES | OFF |
| Wetness | LOW | NO | OFF |
| Dryness | LOW | YES | ON |
| Dryness | HIGH | NO | ON |
Components Assembly of the Automatic Plant Watering System:
To make this simple our preference is to make use of breadboard. If you think to make it more stable you can also solder it to a Dotted PCB and keep it in any small enclosure. You can see the assembled image of the components, made in the breadboard below. We Increased the length of the Wire given in the water Pump and talking about the pump I appreciate you checking the perfectness of the waterproofing of the motor, if not make a proper seal by yourself using some sort of gum or even hot glue works well.
And the main thing we need to discuss here is Power supply. This circuit was made in a way to accept 5V DC input. There are numerous ways to power this circuit like using DC Power Adapters, Mobile chargers, Power banks, etc. I am using a Micro USB Breakout Module to power up the circuit using a USB Cable Connected with the power bank, which can be seen below.
Ensure that the Proper Connections are made between the components and then we can start the installation.
I selected a small indoor plant pot and installed the humidity sensor along with the tube from the water pump, and the water pump itself was placed in the bottle with the big mouth so that the motor could be installed straightaway. The remaining circuit was placed near the pot and powered by the power bank. This Setup can be seen below.
Automatic Plant Watering System using TinkerCad:
Let's simulate the Automatic Plant Watering System using TinkerCad before moving on to a real-time working demonstration. Below, you can access the TinkerCad simulation for the Automatic Plant Watering System:
In the simulation, you'll notice that the working logic appears inverted. This is due to the sensor available in TinkerCad providing an inverted output. However, apart from this inversion, the overall logic and components remain the same.
Working Demo of the Automatic Plant Watering System Project:
As already discussed, this project works by detecting dryness in the soil using a soil moisture sensor and switching ON the mini water pump by now the water starts flowing from the water storage to the Flowerpot and will be turned OFF after a certain amount of delay set via potentiometer once it detects wetness inside the pot. The below video shows how this automatic watering system for potted plants works.
That’s all, we completed our Project.
Here are some hacks you can do in this automatic plant waterer project.
You can change the Q3-BC547_General Purpose NPN Transistor to some other NPN transistor to increase the current capacity to drive the higher power motors.
C1 can be changed as per your need. Using the trial-and-error method, you can find the most suitable one.
You can use a battery system consisting of a Single Li-ion cell, a DC-DC Boost Converter, Battery Charging, and a Protection Circuit to make this project portable.
Apart from this concept of an Automatic Plant Watering system, this circuit has many scopes.
Discover Exciting Projects in a Similar Realm:
If you are interested in building more such projects check out our collection of Arduino Projects. We have more than 500 projects with Code and Circuit Diagram that you can use to build your projects today.
1. How Does a Soil Moisture Sensor Work and How to use it with Arduino?: Curious about soil moisture sensors? This article explains how they work and shows you how to use them with Arduino.
2. Simple Soil Moisture Detector Circuit: Build your own soil moisture sensor with an easy-to-follow circuit.
3. Arduino-based Automatic Plant Irrigation System with Message Alert: Learn to create an automatic plant watering system using Arduino and get text message alerts using the Sim800l module. You'll also set up a 16x2 LCD display for feedback.
4. Low Power IoT Based Compact Soil Moisture Monitoring Device: Make your own battery-powered smart soil moisture sensor using IoT technology, focusing on the ESP8266 module as the main controller.
5. Arduino Smart Irrigation System Using ESP32 and Blynk App: Explore a smart irrigation setup with Arduino and ESP32. This project goes beyond soil moisture sensing, incorporating water level, humidity, and temperature sensors. Discover how to use IoT features with Blynk.
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T Flip-Flop: Circuit, Truth Table and Working
The term digital in electronics represents the data generation, processing or storing in the form of two states. The two states can be represented as HIGH or LOW, positive or non-positive, set or reset which is ultimately binary. The high is 1 and low is 0 and hence the digital technology is expressed as series of 0’s and 1’s. An example is 011010 in which each term represents an individual state. Thus, this latching process in hardware is done using certain components like latch or Flip-flop, Multiplexer, Demultiplexer, Encoders, Decoders and etc collectively called as Sequential logic circuits.
So, we are going to discuss about the Flip-flops in digital electronics. The flip flop aka latches can also be understood as Bistable Multivibrator as two stable states. Generally, these latch circuits can be either active-high or active-low and they can be triggered by HIGH or LOW signals respectively.
The common types of flip-flops are,
Out of the above types only JK and D flip-flops are available in the integrated IC form and also used widely in most of the applications. Here in this article we will discuss about T Flip Flop.
T Flip-flop:
The name T flip-flop is termed from the nature of toggling operation. The major applications of T flip-flop are counters and control circuits. T flip flop is modified form of JK flip-flop making it to operate in toggling region.
Whenever the clock signal is LOW, the input is never going to affect the output state. The clock has to be high for the inputs to get active. Thus, the T flip-flop is a controlled Bi-stable latch where the clock signal is the control signal. Thus, the output has two stable states based on the inputs which have been discussed below.
T Flip Flop Logic Diagram
As you know the Flip flops or the latches are made up of multiple logic gates. Here is the logic diagram for a T flip flop, which is basically created using a number of NAND gates. The basic construction of a T flip flop is almost the same as that of a JK flip flop. The only difference is that the J & K inputs are connected together to make the T input.
Truth Table of T Flip Flop:
Clock | INPUT | OUTPUT | ||
RESET | T | Q | Q’ | |
X | LOW | X | 0 | 1 |
HIGH | HIGH | 0 | No Change | |
HIGH | HIGH | 1 | Toggle | |
LOW | HIGH | X | No Change | |
The T represents the input while the Q and Q’ represent the output states of the flip-flop. The RESET input is used to reset the outputs to the default stat regardless of the clock or T input. During the normal operation, the RESET pin is held HIGH. During this, the outputs will toggle depending on the T input with a corresponding clock pulse. But, the important thing to consider is all these can occur only in the presence of the clock signal. This, works unlike SR flip Flop & JK flip-flop for the complimentary inputs. This only has the toggling function.
T Flip Flop Excitation Table
The excitation Table tells about the excitation which is required by the flip flop to go from the current state to the next state. Here is the excitation table for the T flip flop. Here, whenever T is 0, Qt+1 is the same as input Q. And, whenever T is 1, Qt+1 is a complement of input Q.
RESET: The RESET pin has to be active HIGH. All the pins will become inactive upon LOW at RESET pin. Hence, this pin always pulled up and can be pulled down only when needed.
D and T Flip Flop Comparison
D flip-flops and T flip-flops serve different purposes in digital circuits, with their primary difference lying in their mode of operation. The D flip-flop is straightforward and is used for storing data. It captures the value present at its D input when a clock pulse occurs, and this value is maintained as the output until the next clock pulse. This characteristic makes the D flip-flop a fundamental building block in registers, shift registers, and various other memory devices, as it reliably stores a single bit of data. On the other hand, the T flip-flop is designed for toggling its output state. With each clock pulse, if the T input is HIGH, the output state changes or toggles. If the T input is LOW, the output remains the same. This behaviour makes the T flip-flop particularly useful in applications like counters and control circuits, where a toggle function is required. In essence, while the D flip-flop serves as a data latch, capturing and holding a bit of data, the T flip-flop acts as a controlled inverter, changing its state only when triggered by its T input.
D flip flop to T flip flop Conversion
The simplest way to convert a D flip flop to a T flip flop is to add an XOR gate to the D input. As the below image shows one input of the XOR gate is fed with the T input while the other input is driven by the output.
JK flip flop Using T flip flop
Just like we created a D flip flop using the T flip flop, we can also create a JK flip flop using the very same T flip flop. In the input, we have added two AND gates, one input of each of these is connected to the J and K inputs while the other inputs are connected to the outputs Q and ▁Q. The outputs of these AND gets are then fed to an OR gate. The T input is then fed by the output of this OR gate.
T flip flop Using JK flip flop
Creating a T flip flop using a JK flip flop is very simple. All we have to do is connect the J and K inputs together. Here we have used the MC74HC73A (Dual JK-type flip-flop with RESET). It is a 14-pin package which contains 2 individual JK flip-flops inside. The pin diagram and the function of each pin are given below.
| Pin Name | Function |
Q | True Output |
Q’ | Compliment Output |
CLOCK | Clock Input |
J | Data input 1 |
K | Data input 2 |
RESET | Direct RESET (Low activated) |
GND | Ground |
VCC | Supply voltage |
The IC used is MC74HC73A (Dual JK-type flip-flop with RESET). It is a 14 pin package which contains 2 individual JK flip-flop inside. Above are the pin diagram and the corresponding description of the pins. The J and K inputs will be shorted and used as T input.
Components Required:
- MC74HC73A (Dual JK flip-flop) – 1No.
- LM7805 – 1No.
- Tactile Switch – 3No.
- 9V battery – 1No.
- LED (Green – 1; Red – 1)
- Resistors (1kὨ - 3; 220kὨ -2)
- Breadboard
- Connecting wires
T Flip-flop Circuit diagram and Explanation:
The IC power source VDD ranges from 0 to +7V and the data is available in the datasheet. Below snapshot shows it. Also we have used LED at output, the source has been limited to 5V to control the supply voltage and DC output voltage. We have used a LM7805 regulator to limit the LED voltage.
Practical Demonstration of T Flip-Flop:
The buttons T(Toggle), R(Reset), CLK(Clock) are the inputs for the T flip-flop. The two LEDs Q and Q’ represents the output states of the flip-flop. The 9V battery acts as the input to the voltage regulator LM7805. Hence, the regulated 5V output is used as the Vcc and pin supply to the IC. Thus, for HIGH and LOW inputs at T the corresponding output can be seen through LED Q and Q’.
The pins T, CLK are normally pulled down and pin R is pulled up. Hence, default input state will be LOW across all the pins except R which is in High state for normal operation. Thus, the initial state according to the truth table is as shown above. Q=1, Q’=0. The LEDs used are current limited using 220Ohm resistor.
Note: Since the CLOCK is HIGH to LOW edge triggered, both input button should be pressed and hold till releasing the CLOCK button.
Below we have described the various states of T Flip-Flop using a Breadboard circuit with ICMC74HC73A. A demonstration Video is also given below.
State 1:
Clock– HIGH ; T – 1 ; R – 1 ; Q/Q’ – Toggle between two states.
For the State 1 HIGH inputs at T and clock, the RED and GREEN led glows alternatively for each clock pulse (HIGH to LOW edge) indicating the toggling action. The output toggles from the previous state to another state and this process continues for each clock pulse as shown below.
For first clock pulse with T=1
For second clock pulse with T=1
State 2:
Clock– LOW ; T – 0 ; R – 1 ; Q – 0 ; Q’ – 1
The State 2 output shows that the input changes does not affect under this state. The output RED led glows indicating the Q’ to be HIGH and GREEN led shows Q to be LOW. This state is stable and stays there until the next clock and input is applied with RESET as HIGH pulse.
State 3: The remaining states are No change states during which the output will similar to previous output state. The changes do not affect the output states, you can verify with the Truth Table given above.
The complete working and all the states are also demonstrated in the Video below.
Video
Comments
Thank you, very easy to do, and clear lesson, I appreciate your effort. Awesome.
have a wonderful day.
I need to build a very small board with a receiver flip-flop circuit
to operate remotely on and off 20 tiny LEDs in a string. Can you help
I am new to electronics
Thank you
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How to Build a NAND Gate with Transistors?
In the realm of digital electronics and logic circuits, the NAND gates stands as a fundamental cornerstone that wields immense power in information processing. NAND, short for Negated AND, is a logical operation that produces an output of low only when all of its inputs are high.
In this article, we will go over how to build a NAND gate circuit with transistors.
Transistors serve as the building blocks of logic gates, such as AND gates, NAND gates, OR gates, XOR gates, and other gates that are integral to integrated circuits. In our previous electronic circuits, we have perform XOR Gate, NAND Gate, NOT Gate, NOR Gate, AND Gate, OR Gate, XNOR Gate.
By arranging transistors in specific configuration, we can construct the various gates utilized in electronics.
Any type of transistor, be it BJTs or FETs, can be used to create logic gates. However, in this article, we will use NPN BJTs in order to do it. The 2N2222 transistor is a very common and widely available NPN BJT, is capable of acting as either a switch or an amplifier.
What is a NAND logic gate?
A two-input NAND gate produces a LOW output when both of its inputs are HIGH, and a HIGH output otherwise. Creating a NAND gate using only two transistors is relatively straightforward.
NAND Gate Symbol
Logic NAND Gates are available using digital circuits to produce the desired logical function and is given a symbol whose shape is that of a standard AND gate with a circle, sometimes called an “inversion bubble” at its output to represent the NOT gate symbol with its logical operation given as.
Truth table of NAND Gate
|
Inputs |
Output |
|
|
A |
B |
Y |
|
0 |
0 |
1 |
|
0 |
1 |
1 |
|
1 |
0 |
1 |
|
1 |
1 |
0 |
Boolean expression for this gate is
Y = A.B
So as you can see from the above truth table, a NAND gate exhibits a HIGH output for all condition except when both inputs are 1. In such a scenario, the output will be a logic LOW.
Components Needed for building NAND gate
So with just the few components, we can construct a NAND gate circuit.
- 2 2N2222 (NPN) transistors
- 2 10kΩ resistors
- 2 220Ω resistors
- 1 470Ω resistor
- 2 Push buttons
- A Breadboard
- A 9V Battery
- LEDs and Connecting wires
Circuit Diagram of NAND Gate using Transistors
The circuit diagram below illustrates the NAND gate using 5 NPN transistors. Here, I1 and I2 represent the two inputs, and O1 signifies the output.
Now, let’s dive into the construction of the NAND gate using two NPN transistors.
- Begin by connecting the collector of the first NPN transistor (Q1) to Vcc (positive voltage) with resistor (RS). This establishes the power connection for Q1.
- Connect the emitter of Q1 to the collector of the second NPN transistor (Q2). This establishes a connection between the two transistors, forming the core of our NAND gate.
- Connect the collector of Q1 to the output terminal Y, which will be our NAND gate’s output.
- Next, attach a resistor (R1) between the base of Q1 and the input terminal A. this resistor limits the current flowing into the base of Q1.
- Connect a resistor (R2) between the base of Q2 and input terminal B. similar to R1, R2 controls the current entering the base of Q2.
A simple 2-input NAND gate can be constructed using RTL Resistor-transistor switches connected together as shown above with the inputs connected directly to the transistor bases. Either transistor must be cut-off “OFF” for an output at Y for turn on the led.
A NAND gate circuit is almost identical to an AND gate circuit. The only key difference is that instead of connecting the output to the emitter of the second transistor, the output is obtained to the collector of the first transistor.
When both inputs are set to HIGH, both transistors conduct through their collector-emitter paths, effectively creating a short circuit to ground. This diverts the current away from the output, which in turn causes the output to go LOW.
Conversely, If either transistor turns off, the supply current is unable to flow through the transistors to the ground. Instead, it flows through the output circuit (Led), resulting in a HIGH output. Hence, the output will be HIGH if either one of the inputs is LOW.
Applications
The NAND gate, with its versatile functionality and ability to negate and simplify logical expressions, finds widespread application in various fields. Some notable application of the NAND gate include Digital logic circuits, universal gate, data storage, error detection and correction, programmable logic controllers (PLCs), digital displays, mathematical and computational operations these are just a few example highlighting the wide-ranging application of the NAND gate. Its versatility, efficiency, and ability to simplify complex logic make it an indispensable component in the design and implementation of digital systems across numerous industries.
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How to Build an XOR Gate with Transistors?
In the vast world of digital electronics and logic circuits, The XOR gate stands as a fundamental building block that plays a crucial role in information processing. XOR, short for Exclusive OR. Is a logical operation that produces an output of high when the number of high inputs is odd, and low when the number of low inputs are even. This unique characteristic makes the XOR gate an essential component in various applications, ranging from simple binary arithmetic to complex data encryption algorithms.
In this article, we will explore the inner working of the XOR gate, including its truth table, logical symbol representation, circuit diagram, and practical construction using transistors.
Previously, we have built many electronic circuits to perform logic gates like XOR Gate, NAND Gate, NOT Gate, NOR Gate, AND Gate, OR Gate, XNOR Gate.
What is an XOR Logic Gate?
The XOR gate is also called the exclusive OR gate. An electronic XOR gate performs the digital logic XOR function. This function is generally similar to the standard OR function with one critical difference. For both OR and XOR, the output is high when either of the two inputs are high, and when both inputs are low, the output is low.
However, when both inputs are set to a high state, the standard OR circuit will produce a high output signal, whereas the XOR circuit will generate a low output signal. This fundamental behavior is the reason behind it is called exclusive OR gate. In the simplest design of XOR gate only 5 transistors are needed.
XOR Gate Symbol
Truth table of XOR gate
|
Inputs |
Output |
|
|
A |
B |
Y |
|
0 |
0 |
0 |
|
0 |
1 |
1 |
|
1 |
0 |
1 |
|
1 |
1 |
0 |
Boolean expression for this gate is
Y = (A ⊕ B)
Output
(A ⊕ B) = A.B + A.B
The truth table above shows clearly demonstrates that the output of an Exclusive-OR gate will only goes “HIGH” when both of its two input terminals are at different logic levels with respect to each other. If these two inputs, A and B are both at logic level “1” or both at logic level “0” the output is a “0”.
Logic Diagram of XOR Gate
As can be seen in the logic diagram above, the Ex-OR gate is built by combining three different types logic gates, the OR gate, the NAND gate and the AND gate to produce the desired result.
Components Needed for building XOR gate
So with just the few components, we can construct a XOR gate circuit.
- 2N2222 (NPN) transistors x5
- 10kΩ resistors x3
- 220Ω resistors x3
- Push buttons x2
- Breadboard x1
- 9V Battery x1
- LEDs and Connecting wires
Circuit Diagram of XOR Gate using Transistors
The circuit diagram below illustrates the XOR gate using 5 NPN transistors. Here, I1 and I2 represent the two inputs, and O1 signifies the output.
The picture shows a simple XOR gate circuit that uses 5 transistors. In the layout inputs A and B are both connected to 9V supply. Different color connecting wires help to see the connections. If there is any ambiguity in the placement of wires the circuit diagram can be referenced.
The gate design is a NAND gate on the left two transistors, a switch for the middle transistors, and an OR gate for the last two transistors.
Upon examining the configuration shown in the photo, it becomes evident that the current generated by the far-right resistor is unable to reach the ground on the lest, resulting in the LED remaining off. The reason behind this lies in the fact that all the current generated by the first resistor on the left is directed towards the first ground. Consequently, the switch remains in the off position due to insufficient voltage entering the base of the third transistor.
In the event that one input is activated, the current gains ability to flow from the far-right transistor to the second ground. Finally, when both inputs are deactivated, the output remains off since the current fails to enter the base of the OR gate transistors. this configuration prevents the current from traveling from the far-right resistor to the second ground.
Applications
From the depth of cryptography to the realm of error detection, the XOR gate proves to be an indispensable ally. It possesses the power to perform bitwise operation, enabling binary addition and subtraction, ensuring data integrity, and even generating parity checks. This gate’s versatility and elegance have solidified its role in countless digital system, paving the way for technological advancements that shape our modern world.
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A Simple DIY Bluetooth Audio Player using Wireless Hi-Fi Amplifier Module
The Bluetooth Amplifier Module is useful for DIY projects for creative and hobbyists. The module’s Bluetooth connectivity makes the project connect wirelessly and gives hustle-free entertainment. The board can work on Lithium-ion/Li-Po or Lead Acid battery, which is used to make the device portable. Its design makes it easy to implement the module for projects that are handy, cheap, and provide High Sound Quality.
You can build your own DIY Bluetooth Music Player using Audio Amplifier to use at home/office, or while traveling.
In this project, we will learn the connections and circuitry of the Module. Also, gather some necessary information and Technical Specifications.
Circuit Digest have built many audio circuits, check out the huge collection of audio circuits with schematics and detailed explanation, to help you build Audio projects and use them for your Audio designs. Also check previously built DIY music player:
- MP3 Player Circuit
- Simple Arduino Audio Player and Amplifier with LM386
- DIY ESP32 Based Audio Player
- Subwoofer Amplifier Circuit using IC TDA2030
Wireless Hi-Fi Bluetooth Amplifier Module
Wireless HI-FI module is a Class AB / Class D switching function, 5.3W output power single channel audio power amplifier Board with Built-in Bluetooth, FM, USB, aux cable, and memory chip decoder support.
With its comprehensive set of input ports and impressive features such as compactness, attractive design, and high audio quality, this module stands out from other boards. Its versatility makes it a preferred choice for various applications.
- A power switch to turn ON/Off the module.
- A micro-USB charging connector at fixed 5-volt input.
- AUX-Cable 2.5 mm female Input Jack.
- USB card, TF card Input ports.
- Inbuilt Bluetooth & FM Support.
- A Multi-Purpose Functioning Switch.
- It has two inbuilt Red & Green LED indicators [see their functionality later].
The module has a lot more internal options for supporting other features. The module also has two Open connections to connect MIC and an extra LED for power indication, as indicated in the below diagram.
- Connecting an extra LED to the Board will not be effective as it only indicates the ON/OFF status according to the power switch.
- Soldering a small piece of wire to the FM Antenna Terminal will make the signals and audio quality better while in FM Mode.
- Connecting MIC is very helpful & Futuristic for your project. It allows you to talk on calls during the module connected to the smartphone via Bluetooth or AUX.
Bluetooth Audio Amplifier Circuit Diagram
Let’s have a look at the comprehensive circuit connections of the Board which are very straightforward & simplest design to understand.
Connect the Battery to the battery connector of the module. You can use a 3.7-volt lithium-ion Battery or a 4-volt Lead Acid Battery.
Battery Input-voltage Range: Using this Module, we can able to see the battery draining percentage in our Smartphone. This function purely works based on the Remaining battery voltage which is sensed by the controller IC.
- At 3 volts, it shows the battery fully drained [0%] while at 4.2-volts it sensed the battery as fully charged [100%].
- We can give up to 5 volts to the battery terminals of the module to boost the audio quality performance of the audio IC.
Note: This module can also work with the direct power of a Micro-USB charging Connector whose input is fixed at 5 volts without any battery.
Speaker Matching Specifications
The Module uses a HAA2018 audio IC whose Vdd range is 2.5-5.5 volts. It is a Class AB / Class D switching function, 5.3W output power single channel audio power amplifier IC whose Technical Specification are:
Class D output power:
- 5.3W (VDD=5.0V, RL =2Ω，THD+N=10%)
- 3.2W (VDD=5.0V, RL =4Ω，THD+N=10%)
Class AB output power:
- 5.2W (VDD=5.0V, RL =2Ω，THD+N=10%)
- 3.1W (VDD=5.0V, RL =4Ω，THD+N=10%)
The RL denotes the Load Impedance whereas the VDD is the battery terminal voltage to the audio IC.
Others Features:
- Low distortion and low noise
- Start-up POP sound suppression function
- Shutdown current is less than 1uA
- Overheat protection function
Since, from the above technical specification, you can be aware that at 2Ω Load impedance, the output power will be highest. If you can find 2Ω 5w Speaker, then it will be well & good otherwise you have to set a Series/parallel combination of speakers to match the impedance and power rating according to the output rating of the Amplifier module. In general, it is advisable to match both the impedance and power ratings when connecting speakers and amplifiers. If possible, it is recommended to use a speaker with an impedance that matches the amplifier's output impedance. Additionally, selecting a speaker with a power rating equal to or higher than the amplifier's output power will provide better performance and reduce the risk of damaging the components.
Since our Amplifier output rating is 2Ω 5w, hence I am using two 4Ω 2.5w speakers in parallel connection which is equivalent to the Amplifier output.
Let’s have a look at the real circuit prototype in the below image
Demonstration of Bluetooth Audio Amplifier Board
We have already seen the connection details above, and now we get an insight into the functioning of such a kind of Board like how its indicators work differently in different modes.
- Connect the lithium-ion battery properly by taking care of +ve & -ve correct terminals. Also, connect the speakers with the correct matching for proper audio quality.
- Turn-On the switch and check for a Blue blinking LED.
Mode and LED Indicator
The Module works in different Five types of Modes, these are Bluetooth, FM, AUX, Pendrive, and SD-card Mode. The Blue LED indicator indicates a bit differently in each mode, making it easy to understand the internal functioning of the board.
Bluetooth Mode: The module is always in BT mode by default after turning ON the Board.
- The Blue Led blinks fastly until the BT will not be paired.
- Led Continuous ON after pairing or while pausing the song.
- Blinks Slowly while playing the Song.
FM Mode: Holding & pressing the multi-function button towards the center will change the mode to FM.
- The Blue Led blinks fastly until all the channels will not be scanned.
- Blinks Slowly while playing a channel.
USB/SD-card Mode: The module will automatically initiate the USB-drive mode when you plugged in a USB-Drive.
- Led Continuous ON while pausing the song or if there is no song inside the memory drive.
- Blinks Slowly while playing the Song.
Note: Mp3 songs must be present in the Flash drive otherwise it won’t Access the USB drive.
AUX Mode: Connect an AUX cable to provide audio input to the board from Smartphone.
- Always Blinks Slowly while playing/pausing the Song.
Charging Functionality
It has a Micro-USB input port to charge the Battery pack attached to the Module. There is a Red Led to indicate the charging mode of the module. The Red Led is continuously glowing while battery charging.
Charging voltage at battery terminal: 4 volts
Charging current: ∼200 mA
Note: Don’t charge the device while using it because it will not charge your battery.
Hope you enjoyed the project and learned something useful from it. If you have any questions, you can leave them in the comment section below.
Comments
Can you please describe which Wireless Hi-Fi Bluetooth Amplifier Module you used for this very interesting article? Thank you.
Mike
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How to make a Gyroscope?
Have you ever wanted to try building your own gyroscope? Well, you're in luck! In this blog post, we'll guide you through the steps to make a gyroscope using just a few simple materials.
How does a Gyroscope work?
A gyroscope is a sensor that measures and maintains orientation and angular velocity. It is commonly used in various applications such as navigation systems, robotics, aerospace, and virtual reality devices.
The math behind a gyroscope has to do with how it stays upright. When you spin the small CD attached to the motor, it starts to spin really fast. This creates something called "angular momentum," which is like a special kind of energy that makes things spin around.
The bigger CD is attached to the small CD and motor, so it also starts to spin around. This makes the whole gyroscope spin around as well. But even if you move the gyroscope around, it stays upright because of something called "torque."
Torque is a special kind of force that makes things rotate. When you move the gyroscope around, it experiences torque that causes it to rotate around a different axis. The rate of precession is proportional to the amount of torque applied and the angular momentum of the gyroscope.
The equation for torque is
T = I * α,
Where T = torque applied,
I = moment of inertia (a measure of how difficult it is to rotate an object), and
α = angular acceleration.
So in simpler terms, the faster the small CD spins and the bigger the CDs are, the harder it is to move the gyroscope around because it has a lot of angular momentum.
I hope that helps make it easier to understand!
What you’ll need:
- 1 small DC motor
- 1 big CD
- 1 counterweight
- 1 9V battery
- 1 switch
- Hot glue or double-sided tape
- Small bolt (optional)
Attach CD to Motor
First, take the CD and attach it to the DC motor in the way which is shown in the image above. You can do this using some hot glue or double-sided tape. Make sure the CD is centered on the motor's shaft so that it will spin smoothly.
Attach Counter weight to Motor Shaft
Next, take the counterweight and attach it to the shaft of the motor. You can use a small bolt or some more hot glue to secure the motor shaft to the counter weight. I have used a wheel as a counterweight but it’s not necessary. You can use anything which has a symmetrical shape as the counterweight, but you need to do some trial and error.
Circuit Diagram
Now it's time to wire everything up! First, connect the switch to the 9V battery. Then, connect the positive wire from the battery to the positive terminal on the motor. Connect the negative wire from the battery to the negative terminal on the motor.
Test Your Gyroscope
Once everything is wired up, you can test out your gyroscope by turning on the switch. The motor should start spinning the smaller CD, and the larger CD should rotate around it. You've just created your very own gyroscope!
Experiment!
One of the coolest things about gyroscopes is their ability to maintain their orientation and rotation even when they're disturbed. You can experiment with your gyroscope by tilting it to one side and watching it slowly right itself. Try using different sizes and shapes of CDs to see how they affect the gyroscope's behavior.
Building your own homemade CD gyroscope is a fun and educational project that you can do in just a few hours. Try to make this project and tell us what you learned!
Projects using DC Motor
Control DC Motor with Arduino and L293D Motor Driver IC
Explore the exciting world of robotics and learn how to control DC motors with Arduino and the versatile L293D Motor Driver IC. In this blog post, we'll guide you through the step-by-step process of setting up the motor driver, connecting it to your Arduino board, and programming it to control the speed and direction of your DC motors. Unleash your creativity and bring your robotic projects to life with this essential knowledge!
Simple H-Bridge Motor Driver Circuit using MOSFET
Take a deep dive into motor control as we unveil the secrets of constructing an efficient H-Bridge motor driver circuit using MOSFETs. Our comprehensive blog post will guide you through the circuit building process, shed light on the underlying principles of H-Bridge operation, and empower you to effortlessly control the direction and speed of your DC motors. Expand your technical expertise and unleash the true potential of motor control in your projects with this invaluable knowledge.
Interfacing DC Motor with AVR Microcontroller Atmega16
Are you ready to take your motor control skills to new heights? Join us as we delve into the exciting world of interfacing DC motors with the powerful AVR Microcontroller Atmega16. In our insightful blog post, we'll guide you through the entire process, from establishing a seamless connection to programming the Atmega16 for precise control over the speed and direction of your DC motors. Discover how this integration opens up endless possibilities for your projects, allowing you to unleash the true potential of motor control. Get ready to elevate your technical prowess and create remarkable innovations with AVR Microcontroller Atmega16 and DC motors.
