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Human Following Robot Using Arduino and Ultrasonic Sensor

Submitted by Gourav Tak on

Working of Human Following Robot Using Arduino

In recent years, robotics has witnessed significant advancements, enabling the creation of intelligent machines that can interact with the environment. One exciting application of robotics is the development of human-following robots. These robots can track and follow a person autonomously, making them useful in various scenarios like assistance in crowded areas, navigation support, or even as companions. In this article, we will explore in detail how to build a human following robot using Arduino and three ultrasonic sensors, complete with circuit diagrams and working code. Also, check all the Arduino-based Robotics projects by following the link.

The working of a human following robot using Arduino code and three ultrasonic sensors is an interesting project. What makes this project particularly interesting is the use of not just one, but three ultrasonic sensors. This adds a new dimension to the experience, as we typically see humans following a robot built with one ultrasonic, two IR, and one servo motor.  This servo motor has no role in the operation and also adds unnecessary complications. So I removed this servo and the IR sensors and used 3 ultrasonic sensors. With ultrasonic sensors, you can measure distance and use that information to navigate and follow a human target. Here’s a general outline of the steps involved in creating such a robot.

 

Table of Contents

 

Components Needed for Human Following Robot Using Arduino

  • Arduino UNO board ×1

  • Ultrasonic sensor ×3

  • L298N motor driver ×1

  • Robot chassis

  • BO motors ×2

  • Wheels ×2

  • Li-ion battery 3.7V ×2

  • Battery holder ×1

  • Breadboard

  • Ultrasonic sensor holder ×3

  • Switch and jumper wires

Human Following Robot Using Arduino Circuit Diagram

Here is the schematic diagram of a Human-following robot circuit.

Arduino Human Following Robot Circuit Diagram

This design incorporates three ultrasonic sensors, allowing distance measurements in three directions front, right, and left. These sensors are connected to the Arduino board through their respective digital pins. Additionally, the circuit includes two DC motors for movement, which are connected to an L298N motor driver module. The motor driver module is, in turn, connected to the Arduino board using its corresponding digital pins. To power the entire setup, two 3.7V li-ion cells are employed, which are connected to the motor driver module via a switch.

Overall, this circuit diagram showcases the essential components and connections necessary for the Human-following robot to operate effectively.

arduino human following robot circuit

Circuit Connection:

Arduino and HC-SR04 Ultrasonic Sensor Module:

HC-SR04 Ultrasonic sensor Module

  • Connect the VCC pin of each ultrasonic sensor to the 5V pin on the Arduino board.

  • Connect the GND pin of each ultrasonic sensor to the GND pin on the Arduino board.

  • Connect the trigger pin (TRIG) of each ultrasonic sensor to separate digital pins (2,4, and 6) on the Arduino board.

  • Connect the echo pin (ECHO) of each ultrasonic to separate digital pins (3,5, and 7) on the Arduino board.

Arduino and Motor Driver Module:

  • Connect the digital output pins of the Arduino (digital pins 8, 9, 10, and 11) to the appropriate input pins (IN1, IN2, IN3, and IN4) on the motor driver module.

  • Connect the ENA and ENB pins of the motor driver module to the onboard High state pin with the help of a female header.

  • Connect the OUT1, OUT2, OUT3, and OUT4 pins of the motor driver module to the appropriate terminals of the motors.

  • Connect the VCC (+5V) and GND pins of the motor driver module to the appropriate power (Vin) and ground (GND) connections on the Arduino.

Power Supply:

  • Connect the positive terminal of the power supply to the +12V input of the motor driver module.

  • Connect the negative terminal of the power supply to the GND pin of the motor driver module.

  • Connect the GND pin of the Arduino to the GND pin of the motor driver module.

Human Following Robot Using Arduino Code

Here is a simple 3 Ultrasonic sensor-based Human following robot using Arduino Uno code that you can use for your project.

Ultrsonic Sensors on Robot

This code reads the distances from three ultrasonic sensors (‘frontDistance’, ‘leftDistance’, and ‘rightDistance’). It then compares these distances to determine the sensor with the smallest distance. If the smallest distance is below the threshold, it moves the car accordingly using the appropriate motor control function (‘moveForward()’, ‘turnLeft()’, ‘turnRight()’). If none of the distances are below the threshold, it stops the motor using ‘stop()’.

In this section, we define the pin connections for the ultrasonic sensors and motor control. The S1Trig, S2Trig, and S3Trig, variables represent the trigger pins of the three ultrasonic sensors, while S1Echo, S2Echo, and S3Echo, represent their respective echo pins.

The LEFT_MOTOR_PIN1, LEFT_MOTOR_PIN2, RIGHT_MOTOR_PIN1, and RIGHT_MOTOR_PIN2 variables define the pins for controlling the motors.

The MAX_DISTANCE and MIN_DISTANCE_BACK variables set the thresholds for obstacle detection.

// Ultrasonic sensor pins
#define S1Trig 2
#define S2Trig 4
#define S3Trig 6
#define S1Echo 3
#define S2Echo 5
#define S3Echo 7
// Motor control pins
#define LEFT_MOTOR_PIN1 8
#define LEFT_MOTOR_PIN2 9
#define RIGHT_MOTOR_PIN1 10
#define RIGHT_MOTOR_PIN2 11
// Distance thresholds for obstacle detection
#define MAX_DISTANCE 40
#define MIN_DISTANCE_BACK 5

Make sure to adjust the values of ‘MIN_DISTANCE_BACK’ and ‘MAX_DISTANCE’ according to your specific requirements and the characteristics of your robot.

The suitable values for ‘MIN_DISTANCE_BACK’ and ‘MAX_DISTANCE’ depend on the specific requirements and characteristics of your human-following robot. You will need to consider factors such as the speed of your robot, the response time of the sensors, and the desired safety margin

Here are some general guidelines to help you choose suitable values.

‘MIN_DISTANCE_BACK’ This value represents the distance at which the car should come to a stop when an obstacle or hand is detected directly in front. It should be set to a distance that allows the car to back safely without colliding with the obstacle or hand. A typical value could be around 5-10 cm.

‘MAX_DISTANCE’ This value represents the maximum distance at which the car considers the path ahead to be clear and can continue moving forward. It should be set to a distance that provides enough room for the car to move without colliding with any obstacles or hands. If your hand and obstacles are going out of this range, the robot should be stop. A typical value could be around 30-50 cm.

These values are just suggestions, and you may need to adjust them based on the specific characteristics of your robot and the environment in which it operates.

These lines set the motor speed limits. ‘MAX_SPEED’ denotes the upper limit for motor speed, while ‘MIN_SPEED’ is a lower value used for a slight left bias. The speed values are typically within the range of 0 to 255, and can be adjusted to suit our specific requirements.

// Maximum and minimum motor speeds
#define MAX_SPEED 150
#define MIN_SPEED 75

The ‘setup()’ function is called once at the start of the program. In the setup() function, we set the motor control pins (LEFT_MOTOR_PIN1, LEFT_MOTOR_PIN2, RIGHT_MOTOR_PIN1, RIGHT_MOTOR_PIN2) as output pins using ‘pinMode()’ . We also set the trigger pins (S1Trig, S2Trig, S3Trig) of the ultrasonic sensors as output pins and the echo pins (S1Echo, S2Echo, S3Echo) as input pins. Lastly, we initialize the serial communication at a baud rate of 9600 for debugging purposes.

void setup() {
  // Set motor control pins as outputs
  pinMode(LEFT_MOTOR_PIN1, OUTPUT);
  pinMode(LEFT_MOTOR_PIN2, OUTPUT);
  pinMode(RIGHT_MOTOR_PIN1, OUTPUT);
  pinMode(RIGHT_MOTOR_PIN2, OUTPUT);
  //Set the Trig pins as output pins
  pinMode(S1Trig, OUTPUT);
  pinMode(S2Trig, OUTPUT);
  pinMode(S3Trig, OUTPUT);
  //Set the Echo pins as input pins
  pinMode(S1Echo, INPUT);
  pinMode(S2Echo, INPUT);
  pinMode(S3Echo, INPUT);
  // Initialize the serial communication for debugging
  Serial.begin(9600);
}

This block of code consists of three functions (‘sensorOne()’, ‘sensorTwo()’, ‘sensorThree()’) responsible for measuring the distance using ultrasonic sensors.

The ‘sensorOne()’ function measures the distance using the first ultrasonic sensor. It's important to note that the conversion of the pulse duration to distance is based on the assumption that the speed of sound is approximately 343 meters per second. Dividing by 29 and halving the result provides an approximate conversion from microseconds to centimeters.

The ‘sensorTwo()’ and ‘sensorThree()’ functions work similarly, but for the second and third ultrasonic sensors, respectively.

// Function to measure the distance using an ultrasonic sensor
int sensorOne() {
  //pulse output
  digitalWrite(S1Trig, LOW);
  delayMicroseconds(2);
  digitalWrite(S1Trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(S1Trig, LOW);
  long t = pulseIn(S1Echo, HIGH);//Get the pulse
  int cm = t / 29 / 2; //Convert time to the distance
  return cm; // Return the values from the sensor
}
//Get the sensor values
int sensorTwo() {
  //pulse output
  digitalWrite(S2Trig, LOW);
  delayMicroseconds(2);
  digitalWrite(S2Trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(S2Trig, LOW);
  long t = pulseIn(S2Echo, HIGH);//Get the pulse
  int cm = t / 29 / 2; //Convert time to the distance
  return cm; // Return the values from the sensor
}
//Get the sensor values
int sensorThree() {
  //pulse output
  digitalWrite(S3Trig, LOW);
  delayMicroseconds(2);
  digitalWrite(S3Trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(S3Trig, LOW);
  long t = pulseIn(S3Echo, HIGH);//Get the pulse
  int cm = t / 29 / 2; //Convert time to the distance
  return cm; // Return the values from the sensor
}

In this section, the ‘loop()’ function begins by calling the ‘sensorOne()’, ‘sensorTwo()’, and ‘sensorThree()’ functions to measure the distances from the ultrasonic sensors. The distances are then stored in the variables ‘frontDistance’, ‘leftDistance’, and ‘rightDistance’.

Next, the code utilizes the ‘Serial’ object to print the distance values to the serial monitor for debugging and monitoring purposes.

void loop() {
  int frontDistance = sensorOne();
  int leftDistance = sensorTwo();
  int rightDistance = sensorThree();
  Serial.print("Front: ");
  Serial.print(frontDistance);
  Serial.print(" cm, Left: ");
  Serial.print(leftDistance);
  Serial.print(" cm, Right: ");
  Serial.print(rightDistance);
  Serial.println(" cm");

In this section of code condition checks if the front distance is less than a threshold value ‘MIN_DISTANCE_BACK’ that indicates a very low distance. If this condition is true, it means that the front distance is very low, and the robot should move backward to avoid a collision. In this case, the ‘moveBackward()’ function is called.

if (frontDistance < MIN_DISTANCE_BACK) {
    moveBackward();
    Serial.println("backward");

If the previous condition is false, this condition is checked. if the front distance is less than the left distance, less than the right distance, and less than the ‘MAX_DISTANCE’ threshold. If this condition is true, it means that the front distance is the smallest among the three distances, and it is also below the maximum distance threshold. In this case, the ‘moveForward()’ function is called to make the car move forward.

else if (frontDistance < leftDistance && frontDistance < rightDistance && frontDistance < MAX_DISTANCE) {
    moveForward();
    Serial.println("forward");

If the previous condition is false, this condition is checked. It verifies if the left distance is less than the right distance and less than the ‘MAX_DISTANCE’ threshold. This condition indicates that the left distance is the smallest among the three distances, and it is also below the minimum distance threshold. Therefore, the ‘turnLeft()’ function is called to make the car turn left.

else if (leftDistance < rightDistance && leftDistance < MAX_DISTANCE) {
    turnLeft();
    Serial.println("left");

If neither of the previous conditions is met, this condition is checked. It ensures that the right distance is less than the ‘MAX_DISTANCE’ threshold. This condition suggests that the right distance is the smallest among the three distances, and it is below the minimum distance threshold. The ‘turnRight()’ function is called to make the car turn right.

else if (rightDistance < MAX_DISTANCE) {
    turnRight();
    Serial.println("right");

If none of the previous conditions are true, it means that none of the distances satisfy the conditions for movement. Therefore, the ‘stop()’ function is called to stop the car.

 else {
    stop();
    Serial.println("stop");

In summary, the code checks the distances from the three ultrasonic sensors and determines the direction in which the car should move based on the 3 ultrasonic sensors with the smallest distance.

 

Important aspects of this Arduino-powered human-following robot project include:

  • Three-sensor setup for 360-degree human identification
  • Distance measurement and decision-making in real-time
  • Navigation that operates automatically without human assistance
  • Avoiding collisions and maintaining a safe following distance

 

 

Technical Summary and GitHub Repository 

Using three HC-SR04 ultrasonic sensors and an L298N motor driver for precise directional control, this Arduino project shows off the robot's ability to track itself. For simple replication and modification, the full source code, circuit schematics, and assembly guidelines are accessible in our GitHub repository. To download the Arduino code, view comprehensive wiring schematics, and participate in the open-source robotics community, visit our GitHub page.

Code Schematics Download Icon

 

Frequently Asked Questions

⇥ How does an Arduino-powered human-following robot operate?
Three ultrasonic sensors are used by the Arduino-powered human following robot to determine a person's distance and presence. After processing this data, the Arduino manages motors to follow the identified individual while keeping a safe distance.

⇥ Which motor driver is ideal for an Arduino human-following robot?
The most widely used motor driver for Arduino human-following robots is the L298N. Additionally, some builders use the L293D motor driver shield, which connects to the Arduino Uno directly. Both can supply enough current for small robot applications and manage 2-4 DC motors.

⇥ Is it possible to create a human-following robot without soldering?
Yes, you can use motor driver shields that connect straight to an Arduino, breadboards, and jumper wires to construct a human-following robot. For novices and prototyping, this method is ideal.

⇥ What uses do human-following robots have in the real world?
Shopping cart robots in malls, luggage-carrying robots in airports, security patrol robots, elderly care assistance robots, educational demonstration robots, and companion robots that behave like pets are a few examples of applications.

 

Conclusion

This human following robot using Arduino project and three ultrasonic sensors is an exciting and rewarding project that combines programming, electronics, and mechanics. With Arduino’s versatility and the availability of affordable components, creating your own human-following robot is within reach.

Human-following robots have a wide range of applications in various fields, such as retail stores, malls, and hotels, to provide personalized assistance to customers. Human-following robots can be employed in security and surveillance systems to track and monitor individuals in public spaces. They can be used in Entertainment and events, elderly care, guided tours, research and development, education and research, and personal robotics.

They are just a few examples of the applications of human-following robots. As technology advances and robotics continues to evolve, we can expect even more diverse and innovative applications in the future.

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Joule Thief Circuit: A Low-Power Voltage Booster

Submitted by Vishnu S on

The Joule Thief Circuit is a simple and clever electronic design that can power an LED using a nearly dead battery. The project demonstrates how basic components like a transistor, a toroidal coil, and a resistor can work together to boost a low input voltage to a usable output voltage. By building this circuit, we can explore how a nearly dead battery's energy can be used efficiently without wasting the energy in it. A Joule Thief circuit is a simple voltage booster that uses a toroidal coil, an NPN transistor, and a resistor to extract power from nearly dead batteries. It is a great project for understanding how inductive switching, voltage boosting, and energy-efficient design can be in a practical way. 

For a deeper understanding of boost converter concepts, including switching operation, design principles, and efficiency considerations, refer to Switching Boost Regulator: Design Basics and Efficiency. This resource provides clear explanations of how switching regulators work and how voltage boosting is achieved efficiently in practical circuits.

Table of Contents

What is a Joule Thief Circuit

A Joule Thief circuit is a small, energy-efficient boost converter designed to extract usable power from very low-voltage sources such as “dead” or nearly drained batteries. It uses a transistor, a resistor, and a toroidal coil with two windings to step up the low input voltage and generate high-voltage pulses. These pulses are strong enough to power devices like LEDs, even when the battery voltage is too low to operate them directly.

The joule thief circuit working mechanism relies on rapid switching, turning the transistor ON and OFF many times per second, which stores and releases energy in the coil. This simple circuit is widely used to demonstrate energy harvesting, inductive switching, and efficient power utilisation, making it popular in hobby electronics, education, and low-power lighting applications. This joule thief circuit with toroid operates through self-sustained oscillation, rapidly switching the transistor between conduction and cutoff states thousands of times per second.

Joule Thief Circuit Components: Complete Parts List

The Joule Thief circuit has a minimal set of electronic components that are easy to obtain and assemble. Below the detailed table explaining each component and its purpose in the circuit.

ComponentsQuantityDescription Function in Circuit
NPN Transistor 
(eg.2N2222,2N3904)		1A small-signal transistorActs as a switch, controlling current flow through the coil and enabling voltage boosting
1 kΩ Resistor1Limits current to the transistor basePrevents excessive base current and ensures stable oscillation
Toroidal Coil1Small ferrite core with two windingsStores and releases magnetic energy; provides feedback to the transistor for oscillation
LED1Light Emitting DiodeConverts boosted voltage pulses into visible light
Battery (AA or AAA, 1.5V)1Low-voltage power sourceProvides input voltage, even if weak or partially discharged
Breadboard

1

prototyping boardAllows easy assembly and testing of the circuit without soldering
Connecting WiresAs neededcopper or jumper wiresConnects components to form the complete circuit

The image below displays all joule thief circuit components required for construction. It includes a toroidal inductor for energy storage, an NPN transistor for high-speed switching, a 1 kΩ resistor to control base current, an LED as the load, an AA battery as the low-voltage source, and a breadboard for easy prototyping and testing of the circuit. If you want to learn more about what an NPN transistor is and how it works, check out the article “NPN Transistors.”

Joule Thief circuit components including toroidal inductor, NPN transistor 2N2222, 1kΩ resistor, LED,

Joule Thief Circuit Diagram: Schematic Explained

The joule thief circuit diagram shows how the transistor, resistor, LED, and the two windings on the toroid are connected. It clearly illustrates how the Joule Thief boosts a low battery voltage to power the LED.

Joule Thief Circuit Diagram showing toroid windings, NPN transistor, resistor, and LED connections

This Joule thief schematic clearly illustrates a simple Joule Thief circuit, showing how a low-voltage battery can be boosted to light an LED. In this setup, the core component is a Joule Thief circuit with a toroid, where the toroidal core carries two windings: the primary winding (1 & 2) for current flow and the feedback winding(3 & 4) for rapid switching. This layout helps you understand how the coil windings and the transistor work together to step up the voltage efficiently from even a nearly drained battery. This joule thief circuit diagram demonstrates the critical relationship between components.

Joule Thief Wiring Diagram: Practical Assembly Guide

This wiring diagram shows the practical implementation of the joule thief circuit with toroid, with clearly distinguished coil connections. The primary winding, which carries the main current from the battery, is shown using the red wire, while the feedback (switching) winding, which provides base drive to the transistor, is indicated using the yellow wire. The correct interaction between these two windings enables rapid transistor switching and voltage boosting to power the LED from a low-voltage battery.

oule Thief Circuit Wiring Diagram with color-coded toroid connections

Joule Thief Circuit Working Principle

Understanding the joule thief circuit working requires examining the electromagnetic interactions between the toroidal coil windings and the transistor switching behaviour. The Joule Thief uses a Toroidal coil with two windings :
1. Primary Coil - carries the main current from the battery 
2. Feedback (switching) Coil - controls the transistor switching 
Both coils work together to create a self-oscillating boost converter

⇒ Phase 1: Current Flows in the Primary Coil

When the battery is connected, a small current starts to flow through the primary coil and then to the transistor’s base through the resistor. This turns the transistor slightly ON, allowing current to flow through it. The magnetic field starts building in the primary coil due to the flow of current around the toroid.

⇒ Phase 2: Feedback Coil Activates the Transistor

As the magnetic field builds around the primary coil, it induces a voltage in the feedback(switching) coil. This process occurs due to the mutual inductance. The induced voltage is passed into the transistor, increasing the base current.

As a result, the transistor turns more ON, allowing more current to flow through the primary coil.

This is called the positive feedback, and it forces the transistor to full conduction.

⇒ Phase 3: Core Saturation Occurs

As current continues to flow through the primary winding, the magnetic field in the toroidal core keeps increasing until the ferrite core can no longer store additional magnetic flux. This condition is known as Magnetic Saturation.

Once the core reaches saturation, the induced voltage in the feedback coil starts to drop sharply, causing the base drive of the transistor to disappear. As a result, the transistor switches OFF abruptly.

⇒ Phase 4: Magnetic Field Collapse & High Voltage Spike

When the transistor switches OFF, the current flowing through the primary coil cuts off suddenly.

But the inductors resist the sudden change in the current flow, so the magnetic field collapses rapidly, which is stored in the primary coil. 

This collapse creates a high voltage spike across the primary coil. This spike is much higher than the original battery voltage and is enough to light up an LED.

⇒ Phase 5: Oscillation Begins Again

Once the transistor switches OFF, the current flow through the primary winding stops and the magnetic field in the toroid collapses to ZERO. After this, a small amount of current starts again to flow across the coil and into the transistor’s base through the resistor. This initiates the next switching cycle.

This repeated action causes the primary and feedback windings to continuously force the transistor to turn ON and OFF at high frequency. The frequency is between the hundreds and thousands of times per second, which produces rapid voltage pulses that keep the LED illuminated.

Joule Thief Circuit Simulation: Visual Working Demonstration

Here is the Simulation of the simple Joule thief circuit. It demonstrates how a low-voltage battery is able to power an LED through the rapid switching and voltage boosting. At the beginning, the current starts to flow through the primary winding, causing the transistor to switch ON. The feedback wing then reinforces the base drive, which results in rapid oscillation. The following simulation demonstrates the joule thief circuit working principles in real-time.

Animated Joule Thief Circuit Simulation showing transistor switching and LED operation

As seen in the simulation of the Joule Thief schematic, once the magnetic core reaches saturation, the transistor switches OFF, and the stored magnetic energy collapses, which results in a high-voltage spike across the primary winding. This voltage spike is sufficient to forward-bias the LED, allowing it to glow even though the battery voltage is very low.

The continuous ON & OFF switching cycle is clearly visible in the simulation, and it proves the self-oscillating nature of the Joule Thief Circuit and its ability to efficiently boost voltage from weak power sources.

Practical Working Demonstration: Video Evidence

This practical demonstration showcases a real-world joule thief circuit working behaviour. The LED does not glow when connected directly to the low-voltage battery, but it lights up when connected through the Joule Thief circuit. This happens due to rapid switching and voltage boosting using the toroidal coil. The demonstration confirms the circuit’s ability to utilise energy from weak batteries.

LED connected directly to weak battery showing no illumination

In the above video, the LED is directly connected to the battery, but it does not glow. This happens because the battery voltage is too low to overcome the LED’s forward voltage requirement. Although the battery still contains some energy, it is insufficient to drive current through the LED directly. This observation highlights the limitation of low-voltage sources and sets the foundation for using the Joule Thief circuit, which boosts the voltage and enables the LED to glow even from a weak battery.

Joule Thief Circuit Implementation

LED connected through Joule Thief Circuit showing bright illumination

When the LED is connected through the Joule Thief circuit with toroid, it starts glowing even with the same low-voltage battery. This is because the circuit boosts the battery’s voltage by rapidly switching the transistor and storing energy in the toroidal coil. The collapsing magnetic field generates high voltage pulses that are sufficient to forward bias the LED. This result clearly demonstrates the effectiveness of the Joule Thief circuit in extracting and utilising the remaining energy from weak batteries.

Practical Applications of Joule Thief Circuits

  • Powering LEDs from weak batteries - It can light an LED even when the battery voltage is too low for normal use.
  • Energy harvesting projects - Useful for extracting leftover energy from partially drained cells.
  • Portable emergency lights - Can be used in small flashlights to extend battery life.
  • Educational and hobby electronics - Helps students understand inductive switching, oscillation, and voltage boosting.
  • Low-power sensor circuits - Can drive small sensors or circuits that require a slightly higher voltage.
  • Battery testing demonstrations -  Shows visually how much energy remains in “dead” batteries.

What are some alternatives to the Joule Thief circuit?

∗ Supercharged Joule Thief circuit: The supercharged Joule Thief has a higher efficiency (greater than 80%) than other types of Joule Thief circuits that range from 40-60% efficiency.
∗ Buck-Boost Converters: Used for more powerful applications with a negative voltage output from an input voltage.
∗ Voltage multiplier: Converts lower-voltage AC electricity into DC electricity of a higher voltage.
∗ Split-pi Topology: DC-DC converters that have bidirectional capabilities due to the use of MOSFETs and are suited for regenerative braking systems.

Advantages and Disadvantages of the Joule Thief Circuit

AdvantagesDisadvantages
Can operate from very low input voltagesCan operate from very low input voltages
Utilizes energy from weak or “dead” batteriesOutput voltage is unregulated
Simple circuit with very few componentsNot suitable for high-current loads
Low cost and easy to buildEfficiency drops at higher loads
Self-oscillating (no external controller needed)Generates electrical noise due to switching
Ideal for learning voltage boosting conceptsCannot be used for battery charging
Compact and portable designPerformance depends on coil winding quality

Technical Limitations of the Joule Thief Circuit

  • Low Output Power:
    The Joule Thief can only deliver a small amount of power, making it suitable only for low-power loads such as LEDs.
  • Poor Voltage Regulation:
    The output voltage is not regulated and appears as high-voltage pulses, which are unsuitable for sensitive electronic devices.
  • Low Efficiency at Higher Loads:
    Efficiency decreases significantly when attempting to drive higher current or multiple loads.
  • Limited Current Capability:
    The circuit can boost voltage, but cannot supply high current.
  • Component Sensitivity:
    Performance depends heavily on the type of transistor, coil winding, and core material.
  • EMI and Noise:
    Rapid switching can generate electrical noise and electromagnetic interference.

Frequently Asked Questions About Joule Thief Circuit

⇥ 1. What is the minimum battery voltage needed?
The circuit can often run from as low as 0.5V, depending on components.

⇥  2. Why is it called a “Joule Thief”?
Because it “steals” the remaining energy (joules) from weak or “dead” batteries and makes them usable again.

⇥ 3. Why is a toroidal core used?
The toroid helps create strong magnetic coupling between the two windings, making the switching process efficient.

⇥ 4. Can I use any NPN transistor?
Most general-purpose NPN transistors (like 2N3904, BC547, or 2N2222) will work.

⇥ 5. How does the circuit boost voltage?
It uses a transistor and a two-winding coil to store energy in a magnetic field and release it as high-voltage pulses when the transistor switches OFF.

⇥ 6. Why does the circuit oscillate automatically?
Because the feedback winding sends a signal that rapidly turns the transistor ON and OFF, creating a self-sustaining oscillation cycle.

⇥ 7. Can the Joule Thief charge batteries?
Not directly. It boosts voltage but does not regulate current, so it's not suitable for battery charging without modifications.

⇥ 8. What is the typical operating frequency range of a Joule Thief circuit?
Joule Thief circuits normally operate at oscillation frequencies between 50 and 500 kHz, which are mainly influenced by various factors such as the type of core used for the toroid, the number of turns in the winding, the properties of the transistor, and the load applied.

This tutorial was created by the CircuitDigest engineering team. Our experts focus on creating practical, hands-on tutorials to help makers and engineers learn Raspberry Pi projects, Arduino projects, Electronic Circuit projects and more. 

I hope you liked this article and learned something new from building the Joule Thief circuit. If you have any doubts, you can ask in the comments below or use our CircuitDigest forum for a detailed discussion.
 

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1W LED Driver Circuit

1W LED Driver Circuit

This tutorial shows how to design a high-power LED driver circuit using the LM317 IC. It covers current limiting basics, resistor calculations, power ratings, and practical breadboard testing for reliable LED operation.

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Vector Technics | The Whole Drone Propulsion Stack, Made in Hyderabad

Submitted by Abhishek on

“When we went to the market with only a motor, the customers asked us, ‘Okay, where is the ESC?’” narrated Karna Raj, Co-Founder & Chief Technology Officer of Vector Technics.  Eventually, the company added BLDC motors, propellers, Electronic Speed Controllers (ESCs), Power Distribution Boards (PDBs),  and DC-DC converters to its catalog.  “We just listened to the customer and kept solving the problems. That is how we ended up with so many components.” This habit of listening is what slowly assembled Vector Technics into what it is today. 

Vicharak’s FPGA Boards Start at 349 Rupees and Scale as You Skill Up

Submitted by Abhishek on

Understanding Vicharak starts with the Von Neumann Bottleneck. To those unfamiliar, in short, it’s a fast computer wasting time waiting on memory delivery. At a slightly technical level, dated implementations of the Von Neumann architecture involved moving data between the processor and memory through a single bus, which forced instructions and data to compete for bandwidth.

Built an LED Chaser Circuit with 555 Timer IC and CD4017

Submitted by Vedhathiri on

LEDs are commonly used in electronic circuits, and with the LEDs, you can make many things which are interesting. You’ve probably seen many types of decorative lighting patterns-running lights, festival chasers, or rhythmic blinking effects that instantly stand out. This LED chaser circuit recreates that eye-catching style using a simple combination of the 555 timer IC and the CD4017 counter IC.  An LED chaser circuit using 555 timer IC creates captivating running light effects perfect for decorative displays and electronics projects. With just a handful of components, this LED chaser circuit using 4017 and 555 lets you create smooth, dynamic lighting effects that are perfect for DIY projects, home decor, or electronics learning.  Whether you're building a simple LED chaser circuit for learning or creating an LED chaser light for decoration, this guide covers everything from the 555 timer IC pin diagram to complete circuit assembly. You can also check out our Circular LED Chaser for more inspiration.

Table of Contents

What Does an LED Chaser Circuit Mean?

The LED Chaser Circuit is an electronic formation composed of LEDs that will fire or blink in sequence, creating a running or chasing effect with the lights. The LED chaser circuit using 555 timer IC and the CD4017 decade counter within the LED Chaser Circuit provides accurate timing and sequential output for decorative lighting, electronic displays, and an approach to teaching basic concepts of digital electronics.

Components Required for the LED Chaser Circuit

The LED chaser circuit board requires minimal components, making it an excellent beginner project. The components listed below are the ones used to build the LED Chaser Circuit.

ComponentsQuantity
1K Ohms Resistor1
50K Ohms Variable Resistor1
NE555 IC1
CD4017 IC1
Blue LED10
0.1uf (104) Ceramic Capacitor1
10uF Capacitor1
Power Supply9v

555 Timer IC Pin Diagram and Configuration

Understanding the 555 timer IC pin diagram is crucial for building your LED chaser circuit. Let's discuss the pinout of the 555 timer, which is used in this LED chaser.

555 Timer IC Pin Diagram showing all 8 pins for LED chaser circuit

555 Timer IC Pinout Explained

Pin 1 - Ground:
Connects to the circuit ground and acts as the reference point for the IC.
Pin 2 - Trigger:
A low pulse on this pin (below 1/3 of VCC) sets the internal flip-flop and makes the output go HIGH.
Pin 3 - Output:
Provides the output signal. It can source or sink current and drive loads up to about 200mA.
Pin 4 - Reset:
Active-LOW reset input. Pulling it LOW forces the output LOW. Usually tied to VCC to avoid accidental resets.
Pin 5 - Control Voltage:
Allows external control of the threshold level. Normally connected to ground through a 0.01µF capacitor to reduce noise.
Pin 6 - Threshold:
When the voltage on this pin reaches 2/3 of VCC, it resets the flip-flop, and the output goes LOW.
Pin 7 - Discharge:
Connected to an internal transistor. When the output is LOW, this pin is pulled to ground and discharges the timing capacitor.
Pin 8 - VCC:
Power supply pin. Connects to a positive voltage (typically 3.6V to 15V).

PIN Number

PIN Name

Function

1

Ground (GND)

Circuit reference point, connects to the negative supply

2

Trigger

Initiates timing cycle when voltage drops below 1/3 VCC

3

Output

Provides clock pulses to CD4017 (up to 200mA)

4

Reset

Active-LOW reset; connected to VCC for normal operation

5

Control Voltage

Noise filtering point; connected to ground via 0.01µF capacitor

6

Threshold

Compares voltage to 2/3 VCC; resets flip-flop when exceeded

7

Discharge

Discharges the timing capacitor when the output is LOW

8

VCC

Positive power supply (4.5V to 16V, typically 9V)

CD4017 IC Pinout and Functionality

The CD4017 decade counter is the heart of sequential control in this LED chaser circuit using 4017 and 555.

CD4017 IC Pin Diagram for LED chaser circuit showing all 16 pins

CD4017 Pin Configuration Details

Pin 1-7, 9-11 - Outputs (Q0-Q9):
These are the ten decoded outputs of the counter. Only one output goes HIGH at a time, advancing with each clock pulse.
Pin 8-Ground:
Connected to the circuit ground.
Pin 12-Carry Out (CO):
Goes HIGH after every 10 clock pulses. Useful for cascading multiple CD4017 ICs.
Pin 13-Clock Enable (CE):
Active-HIGH pin. When HIGH, the IC ignores clock pulses. When LOW, counting works normally. Often tied to the ground.
Pin 14-Clock Input:
Receives the clock signal. Each rising edge of the clock moves the counter to the next output.
Pin 15-Reset:
Active-HIGH reset input. When taken HIGH, the counter jumps back to Q0. Usually connected to ground during normal operation.
Pin 16-VCC:
Power supply pin. Works between 3V and 15V, depending on the version.

PIN(S)

Name

Function in LED Chaser

1-7, 9-11

Q0-Q9 (Outputs)

Connect to LEDs; only one goes HIGH at a time

8

Ground (VSS)

Common ground connection

12

Carry Out (CO)

Pulses HIGH every 10 counts (for cascading)

13

Clock Enable

Connected to the ground for continuous operation

14

Clock Input

Receives pulses from 555 timer (Pin 3)

15

Reset

Connected to ground for normal counting

16

VDD (Power)

Positive supply (3V-15V, typically 9V)

LED Chaser Circuit Diagram

This LED chaser circuit diagram shows the complete schematic for building your LED chaser light. This is how the components are assembled to make the circuit of the LED chaser. 

Complete LED chaser circuit diagram using 555 timer IC and CD4017

This image shows a circuit simulation of a 555 timer connected to a CD4017 decade counter on a breadboard. A 9V battery powers the setup, and the LEDs are arranged in a step pattern to create a running light effect. The potentiometer adjusts the speed of the LED sequence.

LED Chaser Circuit Board Assembly

Building your LED chaser circuit board requires careful component placement. This real-time setup demonstrates proper breadboard assembly for the simple LED chaser circuit. The setup below shows how the components are assembled in real-time.

LED chaser circuit board assembly on breadboard with 555 timer and CD4017

Step-by-Step Assembly Instructions

Test the LED chaser circuit using 555 timer IC before building it physically using this TinkerCAD simulation:

https://www.tinkercad.com/things/20r5BxmLEB3-led-chaser

This online simulation shows the circuit uses a 555 timer to generate pulses and a CD4017 counter to drive the LEDs in sequence, creating a chaser effect.
The potentiometer changes the RC time constant of the 555 timer.
Higher resistance → slower pulses → slower LED chasing.
Lower resistance → faster pulses → faster LED chasing.

→ Step 1: Connect the Positive (Red) 9V Battery to Power and the negative (Blue) 9V Battery to Ground

→ Step 2: Insert the 555 Timer IC, placing Pin #1 next to the Ground Rail and Pin #8 next to the Power Rail

→ Step 3: Have all timing components fully installed. A 1K Ohm Resistor, 50K Potentiometer, and 10uF Capacitor are all necessary as shown in the schematic.

→ Step 4: Install the CD4017 IC properly and connect Pin #14, which is the only output of the 555 timer (Pin #3).

→ Step 6: Build your LED Array. You need a total of 10 LEDs, 220 Ohm Current Limiting Resistors for each LED, connected to all outputs of the CD4017.

→ Step 7: Insert Decoupling Capacitors into the VCC and GND, between both ICs, using 0.1uF capacitors.

→ Step 8: Before applying power to the final product, double-check that all connections are correct.

How the LED Chaser Circuit Works

The LED chaser circuit using 4017 and 555 operates through synchronised timing and sequential control:

Working LED chaser circuit showing sequential LED illumination pattern

This image shows a complete breadboard setup powered by a 9V battery, where a 555 timer is used to generate clock pulses for a CD4017 counter IC. The wiring connects the IC outputs to a series of LEDs arranged on the right side to create a running-light pattern. A potentiometer is included to adjust the timing speed, and the entire layout clearly demonstrates how the 555 and CD4017 work together in a simple LED chaser circuit. Increasing resistance slows the RC time constant, producing slower pulses and a gradual LED chaser light effect.

In this LED chaser circuit, a 555 timer is used as a pulse generator, producing a steady stream of on-off signals at a fixed speed. These pulses are sent to the clock input of the CD4017, a decade counter that moves its output from one pin to the next each time a pulse arrives. Each output pin is connected to an individual LED through a resistor, so every incoming pulse makes the next LED glow while the previous one turns off, resulting in a clean chasing or running-light effect. After the last LED in the sequence turns on, the counter returns to the first output and the pattern repeats continuously. The Reset and Clock Enable pins are kept at fixed levels so the counting proceeds smoothly without interruption, and both ICs share the same power and ground to keep the circuit stable. Do check out our Building a LED Dimmer Circuit using 555 Timer IC and BC557 Transistor, which will give you a clear idea about the 555 Timer IC and BC557 Transistor.

Real-Time Working Demonstration of the LED Chaser Circuit

Watch the LED chaser light pattern in action.

LED Chaser working demonstration

This shows the change in the LED pattern. If the potentiometer is adjusted, the LED will start to speed up or slow down; these changes cause the LED to blink in a pattern.

Speed Control Mechanism

The 50kΩ potentiometer within the [155]555 Timer circuit determines the speed of the chasing LEDs via:

  • Maximum Resistance (50kΩ) provides a slow, smooth movement of LEDs at approximately 0.7 Hz.
  • Mid-point Resistance (25kΩ) produces a moderate chasing speed of around 1.4 Hz.
  • Minimum Resistance (1kΩ) produces a very fast-paced pattern of LED operation of about 7 Hz.

Troubleshooting the LED Chaser Circuit

Problem

Possible Cause

Solution

No LEDs light up

Power supply disconnected or incorrect polarity

Check the 9V battery connection and polarity

All LEDs glow dimly

Missing current-limiting resistors

Install a 220Ω resistor in series with each LED

LEDs don't chase sequentially

555 output not connected to CD4017 clock

Verify the connection between Pin 3 (555) and Pin 14 (CD4017)

Pattern repeats only partially

CD4017 Reset pin incorrectly wired

Ensure Pin 15 (Reset) is connected to ground

Speed doesn't change with the potentiometer

Potentiometer wiring error

Check R2 (pot) connections to Pin 7 and timing capacitor

Erratic or random LED behaviour

Missing decoupling capacitor

Add a 0.1µF capacitor between VCC and GND near ICs

Enhancements and Modifications

1. More LED Count (20 LEDs)
To get 20 outputs in sequence, 2 CD4017s can be cascaded by connecting Pin 12 (Caraout) of the first to Pin 14 (Clock) of the second.

2. To have a bidirectional chase pattern
To make a chase pattern that reverses, create a CD4029 up/down counter to control a reverse clock signal, or use a 2nd CD4017 and connect alternate LED connections to change their glow direction.

3. A Multi-Colour LED Chase
You can replace the standard red LEDs with RGB LEDs. And by adding three additional CD4017 ICs (P151, P122, and P133) for each primary colour, you're now able to control your colours separately with the three channels you'll create.

4. Sound-Responsive LED Chaser
Instead of a 555 timer circuit, you can add a microphone preamp with a comparator circuit that will let you have lighting effects synced to your music!

Frequently Asked Questions

⇥ 1. Why does only one LED glow at a time?
Only one LED lights up at a time because the CD4017 IC sends a high signal to one output pin at a time.
With each clock pulse, the high signal moves to the next pin, turning on the next LED in a sequence and creating the chasing effect.

⇥ 2. What is an LED chaser circuit?
An LED chaser circuit is a setup where LEDs light up one after another in a sequence, making a running light effect. This kind of setup is often used in decorative lighting and display applications.

⇥ 3. What components are mainly used in this circuit?
This project uses two main integrated circuits (ICs):

  • 555 Timer IC-It is used to generate continuous clock pulses.
  • CD4017 Decade Counter IC-It controls the sequence of LEDs by activating them one after another based on the clock pulses.

⇥ 4. How does the 555 Timer work in this project?
The 555 Timer is set up in astable mode, which means it continuously creates pulses. These pulses are sent to the CD4017’s clock input and determine how fast the LEDs turn on and off.

⇥ 5. What does the CD4017 IC do?
The CD4017 is a 10-stage counter IC. Every time a pulse is received, it moves the high signal to the next output pin, starting from Q0 to Q1, then Q2, and so on up to Q9. This causes the LEDs connected to these pins to light up one after another.

⇥ 6. How can I change the speed of the LED chasing pattern?
You can adjust the speed by changing the resistance of the potentiometer connected to the 555 Timer. A higher resistance results in slower pulses, making the LEDs move more slowly. A lower resistance results in faster pulses, making the LEDs chase each other more quickly.

⇥ 7. What power supply is required for this circuit?
This circuit can be powered by a 9V battery or a DC supply that provides 5 to 12 volts. Both the 555 Timer and the CD4017 IC operate within this voltage range.

This tutorial was created by the CircuitDigest engineering team. Our experts focus on creating practical, hands-on tutorials that help makers and engineers master Raspberry Pi projects, Electronic Circuit projects and IoT development projects.

I hope you liked this article and learned something new from it. If you have any doubts, you can ask in the comments below or use our Circuit Digest forum for a detailed discussion.
 

LED-Based Electronics Projects

Below are a few projects that highlight basic electronics concepts through LED patterns and control logic.

LED Chaser using Arduino and Rotary Encoder

LED Chaser using Arduino and Rotary Encoder

In this project, we are going to interface a ROTARY ENCODER with ARDUINO. A ROTARY ENCODER is used to know the position of movement and the angular movement of a motor or axis. It’s a three-terminal device, usually, with power and ground pins; there are a total of 5 terminals. 

Decimal Counter Circuit

Decimal Counter Circuit

Here we are going to use a 10-bit DECADE counter. The counter chip is CD4017BE. With a 10-bit DECADE counter, we can count events up to 10. So it would take 11 clock pulses for the chip to reset itself to zero.

LED Roulette Circuit using 555 timer IC

LED Roulette Circuit using 555 timer IC

Here we are going to show you how to make an LED Roulette Circuit using a 555 timer IC. Roulette is a casino game named after the French word, which means little wheel.

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Top 10 Open-Source Robotic Arms For Beginners

Submitted by Vedhathiri on

A robotic arm is one of those classic projects that almost every electronics enthusiast tries at some point. It’s a perfect mix of mechanics, electronics, and hands-on creativity and building one teaches you more than any textbook ever could. When most people think of robotic arms, they picture the big, ultra-precise industrial robotic arm machines found in factories or the sleek robots we see in movies like Iron Man(Dummy). Those are exciting to look at, but far too complex for someone who just wants to learn and experiment. 

In this article, we’re keeping things simple and practical on beginner-friendly open source robotic arms that you can actually build at home. Instead of industrial-grade robots, we’re focusing on beginner-friendly robotic arm designs that you can actually build at home. No heavy components, no expensive hardware, and no advanced engineering background required. Every simple robotic arm project featured here is open-source, easy to understand, and designed for newcomers who want to learn the basics of robotic movement, servo control, and simple automation.

Whether you're looking for a simple robotic arm using Arduino, a complete 6-axis robotic arm, or a functional pick and place robotic arm, this list covers a wide range of designs that help you understand everything from basic servo control to multi-axis movement. All robotic arm projects include complete robotic arm 3D models, source code, and assembly instructions. If you are more interested in Robotics, do check these Robotic Projects.

Table of Contents

What is a Robotic Arm? Understanding the Fundamentals

Multi-joint industrial robotic arm showing 6-axis articulated design with gripper end-effector

A robotic arm is a mechanical device which is designed to replicate the movements and functions of the human arm. It is designed to perform tasks with precision, reproducibility, and, in many situations, complete programmable control. Most robotic arms are made up of many stiff parts joined by joints, allowing the robotic arm to move in different directions with a degree of freedom(DOF). The more degrees of freedom an arm has, the more adaptable and capable it is. 

Industrial robotic arms exist in a variety of fields. In factories, workers assemble cars, weld metal, pick and arrange components, and paint surfaces with perfect consistency. In medicine, they help the surgeons in operations where accuracy and steadiness play a major role. They are also widely used in laboratories, space missions, and educational settings. At the core, all robotic arm for beginners projects rely on a few key components:

Core Components of Every Robotic Arm

At the core, a robotic arm with a servo motor relies on essential components in Open Source Robotic Arms:

  • Actuators - servos or motors that control the movement.
  • Controller - the brain of the system, which processes the data, controls the other components, etc…
  • End-effector -  the tool that is attached at the end of the arm, which is known as a gripper, camera, or scalpel, depending on the process of the project.

Together, these parts allow a robotic arm to interact with its environment in a controlled and purposeful way. Whether it’s lifting small objects, performing surgical procedures, or assembling complex products, the flexibility of robotic arms makes them one of the most powerful tools in modern technology.

Robotic arm anatomy diagram comparing human arm joints to mechanical joints in 6-axis configuration

This image compares a robotic arm to a human arm, showing how each joint-shoulder, elbow, wrist, and hand is designed to mimic human movement. It highlights the similarities in structure and function between the two

How We Selected These Open Source Robotic Arm Projects

To make this simple and easy to build, several criteria need to be focused on; they are 

  • Open-source files availability (STLs, code, schematics)
  • Beginner-friendly assembly
  • Affordable parts

To ensure these robotic arm projects are genuinely beginner-friendly and practical for learning, we evaluated each design against specific criteria that matter most to newcomers building their first DIY 3D printed robot arm:

Selection Criteria

Why It Matters

What We Look For

Open-Source Files

Complete STL files, code, and schematics eliminate guesswork

Full 3D models, Arduino/C code, wiring diagrams, BOM

Beginner Assembly

Simple tools and clear instructions reduce barriers to entry

Basic screwdriver assembly, no CNC/welding required

Affordable Parts

Budget-friendly components make projects accessible to everyone

Hobby servos (SG90, MG995), common Arduino boards, 3D printed parts

Clear Documentation

Step-by-step guides ensure successful builds

Assembly videos, detailed tutorials  and troubleshooting tips

1. Open-Source Files Availability (STL Models, Code, Schematics)
Beginners struggle with mechanical design, motor control, and basic kinematics knowledge. Open-source robotic arm, schematics, and source code make the learning process easier by giving complete, ready-to-use resources, which are very helpful for the initial setup. All robotic arms in this article provide fully accessible open-source files to help you start confidently.

2. Beginner-Friendly Assembly Process
Even with the open-source design files, building a DIY 3D-printed robot arm on your own can be a tough task without the proper tools. It's important to choose the designs that can be assembled easily with the help of simple tools. This ensures the beginners can build their own robotic arm DIY project without the need for any advanced tools.

3. Affordable and Accessible Components
Some robotic arms require costly components, making them difficult for beginners to try. Designs that use budget-friendly, easily available parts like hobby servos, 3D-printed pieces, and basic electronics keep the simple robotic arm projects affordable and beginner-friendly.

Essential Terms Every Robotic Arm Builder Must Understand

Before diving into the robotic arm projects, it's crucial to understand the fundamental concepts that apply to every robotic arm design. 

1. Joints - The Foundation of Movement
Joints are the moving links in a robotic arm. They let the arm bend, rotate, or change direction, similar to how our elbows and wrists work. In a 6-axis robot arm project, six independent joints work together to achieve complex spatial positioning.

2. Degrees of Freedom (DOF) - Measuring Movement Capability
Degrees of freedom describe how many independent motions a robotic arm can make. Understanding DOF is essential when selecting a robotic arm for beginners:

For example:

  • 1 DOF means the arm moves in just one direction.

  • 3 DOF means it can move up and down, side to side, and also rotate.
    The higher the DOF, the more flexible and capable the arm becomes.

3. End-Effector - The Working Tool
The end-effector is the tool attached to the tip of the robotic arm. It could be a gripper, a suction cup, a pen, a welding tool, or anything the arm needs to use to perform a task.

4. Servo Motor Fundamentals - Powering Precision Movement
A robotic arm with a servo motor achieves precise positioning through these electromechanical devices. They rotate to specific angles based on the signals they receive. A robotic arm with a servo motor achieves precise positioning through these electromechanical devices.

A few key points:

  • They can only rotate within a set angle range (like 0-180°).
  • They provide precise position control.
  • Their torque determines how much weight the arm can lift.
    If you find it difficult to understand how a servo motor works, our tutorial on How to Control a Servo Motor Using Arduino will guide you step-by-step and make the concept much easier to follow.

5. 3D Design and Modelling for Robot Arms

3D design is the process of creating the arm’s parts in CAD software such as Fusion 360 or SolidWorks. These robotic arm 3D models are later 3D-printed or machined. Good 3D design ensures the parts fit well, move smoothly, and are strong enough for the job. Most open source robotic arms also provide complete robotic arm 3D models, which include STL files, assembly diagrams, and joint layouts that beginners can follow easily while printing or modifying the design.

6. Number of Axes - Movement Dimensions

Axes describe the different directions in which the arm can move.
For example:

  • A 2-axis arm can move in only two directions.
  • A 4-axis arm has more reach and versatility.
  • A 6-axis arm offers very smooth and complex movement, similar to industrial robots.

7. Rotation Limits and Range of Motion

Every servo or joint has a maximum angle it can turn. Many hobby servos rotate up to 180°, while some specialised servos or mechanical joints can rotate a full 360°.  These physical limits define workspace boundaries and influence arm design for robotic arm DIY projects.

8. Payload Capacity - Weight Handling Capability

Payload is the maximum weight the robotic arm can safely lift and hold. It depends on factors like the servo’s torque, the length of the arm, and the strength of the materials used. If the payload is too high, the arm may wobble, bend, or cause the motors to stall. Exceeding payload capacity causes motor stalling, joint bending, structural failure, or erratic movement in your DIY 3D printed robot arm.

9. Power Supply Requirements - Critical Electrical Considerations

Robotic arm projects with multiple servo motors, especially those using multiple servos, need a stable and sufficient power source.
Beginners often forget that:

  • USB power is not enough
  • Servos need separate power
  • Current rating (amps) matters as much as voltage
  • A weak power supply causes shaking, overheating, or servo failure.

A quality 5V/5A power supply prevents these issues in multi-servo simple robotic arm projects.

10. Control System Selection - Choosing the Right Brain

The microcontroller selection determines your robotic arm for beginners' capabilities and expansion potential:

  • Arduino for simple pick-and-place
  • Raspberry Pi for advanced control
  • ESP32 for wireless control
  • Choosing the right controller prevents limitations later.

Top 10 Open Source Robotic Arm Projects for Beginners

Each robotic arm project listed below includes complete build files, source code, and ready-to-use robotic arm 3D models, making it easier for beginners to assemble and understand the mechanical structure. All projects are thoroughly tested, documented, and proven to work for newcomers to robotic arm DIY projects. Let's dive in

1. Object Following Robotic Arm - AI-Powered Tracking System

4-DOF object tracking robotic arm using Arduino UNO with ultrasonic and IR sensors for autonomous object following

This simple robotic arm project helps you build a 4DOF  robotic arm using Arduino UNO controlled by an Arduino UNO controller that can track moving objects. The arm uses four SG90 servo motors managed by a PCA9685 PWM driver, while an ultrasonic sensor and two IR sensors detect object movement. As the object moves, the arm automatically adjusts its position, moving right, left, down or up. The Arduino code includes libraries for precise servo control and sensor reading, making the setup both interactive and responsive. With affordable, modular hardware, this project is an excellent hands-on introduction to robotics, automation, and Object-tracking systems for beginners and hobbyists.

Project Source: Arduino Project Hub (roboattic_lab).
Original Project Link: https://projecthub.arduino.cc/roboattic_lab/build-your-own-object-tracking-4-dof-robotics-arm-with-arduino-dd36ba

2. Robotic Arm using ARM7-LPC2148 Microcontroller - Embedded Systems Learning

4-DOF pick and place robotic arm controlled by LPC2148 ARM7 microcontroller with potentiometer manual input

This robotic arm DIY project uses the LPC2148-based robotic arm design project, which is based on a simple concept: using four potentiometers to directly control the four joints of a lightweight pick-and-place arm. Each joint is powered by an SG90 servo, and the microcontroller reads the position of the potentiometers through its analog-to-digital converter pins. As you turn a knob, the matching servo moves to the new angle, allowing the arm to respond in real time. The joints include base rotation, vertical lifting, forward reach, and a small gripper, which offers enough flexibility for basic object handling. A set of indicator LEDs shows which motor is currently active. The servos are connected to a separate 5 V power supply to ensure system stability, while the microcontroller operates on 3.3 V. The firmware is written in Keil and uploaded using Flash Magic, making direct use of the chip’s ADC, GPIO, and PWM features. Overall, it’s a clean and practical way to get started with embedded robotics, demonstrating how an ARM microcontroller can be used to control a multi-axis robotic arm using simple analog inputs. The project implements a straightforward yet effective control scheme: four potentiometers directly control four joints of a lightweight pick-and-place robotic arm.  The four-joint configuration includes base rotation (360° workspace), vertical shoulder lift, forward elbow reach, and a functional robotic arm gripper—offering sufficient flexibility for basic object manipulation tasks and pick-and-place operations.

Project Source: Circuit Digest-LPC2148 Robotic Arm Project. The 3D printed Robotic Arm used in this tutorial was made by following the design given by EEZYbotARM, which is available on Thingiverse.

Project Link: https://circuitdigest.com/microcontroller-projects/diy-robotic-arm-using-lpc2148-microcontroller

3. Dolphin 3D-Printed Robotic Arm - Smooth Articulation Design
 

A compact and smooth 3D-printed robotic arm model known as the Dolphin Arm, featuring lightweight articulated joints.

The Dolphin Robotic Arm is a smoothly designed, DIY 3D printed robot arm project made for makers looking for a simple yet functional robotic arm. Its design emphasises stability and smooth movement, with several rotating joints that let it perform basic pick-and-place tasks. The parts are easy to print and put together, and the creator offers all the necessary files, a list of materials, and step-by-step instructions, making it easy for even new builders to follow. The arm uses common hobby servos, which means the electronics are affordable and simple to control using an Arduino or similar microcontroller. As a whole, it's a small, user-friendly robotic arm that helps beginners learn about joint movement, servo control, and the fundamentals of pick-and-place robotic arm systems. Feature optimised robotic arm 3D model files for standard FDM printers (0.2mm layer height). This project serves as an excellent entry point for beginners who want to understand joint kinematics, servo motor control fundamentals, and the mechanical principles that govern simple robotic arm projects.

Project Source: MakerWorld – Dolphin Robotic Arm Model.
Original File Link: https://makerworld.com/en/models/91498-dolphin-arm-robotic-arm

4. ESP32 Robot Arm with Smartphone Control - Wireless Web Interface

A robotic arm with a servo motor achieves precise positioning through these electromechanical devices. Key specifications include:

4-DOF robotic arm using ESP32 with web-based smartphone control interface for wireless operation

This modern robotic arm project, using an Arduino-compatible ESP32 platform, demonstrates wireless control capabilities through an intuitive web-based interface. The ESP32 runs a web-based interface where users can adjust each joint base, elbow, shoulder and robotic arm gripper using sliders on the screen. As you move the sliders, the servos which are present respond instantly, allowing for real-time adjustments. The system can also include record and playback functions, enabling you to save a sequence of movements and replay them later when needed. The frame is lightweight and can easily be constructed using 3D printing, making it easy to assemble each and every part, which is ideal for beginners who want to explore the servo control, wireless communication and web-based robotics.  As you move the on-screen sliders, the servo motors respond instantly with minimal latency, enabling real-time adjustments and smooth coordinated motion. Features a lightweight DIY 3D printed robot arm frame optimised for servo torque. This is an ideal project for beginners interested in exploring wireless robotics, web-based control interfaces, and IoT (Internet of Things) integration with robotic arm designs.

Project Source: YouTube Creator (Channel Name: hash include electronics).

Original Video Link: https://www.youtube.com/watch?v=cVSvg6VQhGU

5. 3D-Printed 6-DOF Arduino Robotic Arm - Advanced Multi-Axis Control

This comprehensive 6-axis robot arm project features a complete 6-axis robotic arm design with full spatial positioning capability, enabling it to move naturally and perform complex manipulation tasks similar to human arm capabilities.

Fully 3D-printed 6 axis robotic arm powered by Arduino for complex spatial manipulation tasks

This is a complete 3D-printed robotic arm with six degrees of freedom (DOF), allowing it to move flexibly and naturally, similar to a human arm. The project uses an Arduino UNO as its main control board, which sends signals to several servo motors to control the movement of each joint. Because of these six degrees of freedom, the arm can move in many different directions, giving it the ability to do complex tasks, not just simple ones like picking up and placing objects. The whole structure is made from 3D-printed parts, making it inexpensive and easy to build for people who are just starting out. The design is also modular, meaning each joint is separate and controlled by its own servo motor. This makes putting it together much easier, and you don't need any specific tools or machines to assemble it.  These robotic arm 3D models are exported as STL files for 3D printing or used to generate machining instructions. Most open-source projects provide complete robotic arm 3D models, including STL files, assembly diagrams, and detailed joint layouts that beginners can follow while printing or modifying the design for custom applications. This configuration enables the arm to reach any point within its workspace while maintaining complete control over tool orientation, capabilities typically found only in professional industrial robotic arms. This robotic arm for beginners project teaches advanced concepts while remaining achievable for dedicated hobbyists.

Project Source: YouTube Creator (Channel Name: Oliver Paff)

Original Video Link: https://www.youtube.com/watch?v=n8HHMt3xdFA

6. DIY 6-DOF Robot Arm with Arduino - Production-Grade Design

DIY six-axis robotic arm built with 3D-printed parts controlled by Arduino for precise multi-axis manipulation

This project features a 6-axis robot arm project, which is built from 3D-printed components and controlled by an Arduino. With six independent axes of motion, the arm can perform complex manipulation tasks, not just simple pick and place tasks. Each joint (base, shoulder, elbow, wrist, and gripper) is controlled by a servo or similar actuator, giving it a wide range of motion. The design is compact and also strong, and the use of 3D-printed parts makes it affordable and accessible for beginners and learners. The Arduino controller sends PWM signals to each motor, enabling precise and coordinated movement across all joints. The open-source nature of the design (with publicly shared STL files and code) makes it ideal for anyone who wants to build, modify, or extend the arm for their own robotics experiments. This configuration mirrors the joint structure found in professional industrial robotic arms used in manufacturing automation. The characteristic reinforced DIY 3D printed robot arm structure handles a moderate payload (200-300g).

Project Source: YouTube Creator (Channel Name: Lee Curiosity).
Original Video Link: https://www.youtube.com/watch?v=bNzVCNyYDzM

7. STM32 Robot Arm With Smartphone Control - Professional Embedded Design

6-DOF robotic arm operated using STM32 and ESP32 with smartphone-based Bluetooth motion control interface

This advanced robotic arm DIY project features a 6-DOF robotic arm design powered by a mix of MG995 and SG90 servo motors. It uses an STM32F103 (Blue Pill) as the main controller, while an ESP32 handles Bluetooth communication with a simple MIT App Inventor-based smartphone app. Commands sent from the smartphone are passed to the STM32, which drives each servo using precise PWM control. The design includes a custom PCB, stable power regulation, and complete build files, making it a practical and well-documented project for anyone who wants to explore embedded side and wireless robotics. The system represents a step up from basic robotic arm using Arduino projects, demonstrating embedded systems design practices used in commercial robotics products.

Project Source: Hackster.io - Labirenti Project Page.
Original Project Link: https://www.hackster.io/Labirenti/stm32-robot-arm-with-smartphone-control-92955b

8. DIY Robotic Arm - Simple Yet Functional Design

Simple 3D-printed robotic arm from Printables designed for beginners learning servo-based movement control

This straightforward, simple robotic arm project uses 3D printing and regular servos for each joint, keeping costs low and assembly simple. This do-it-yourself robotic arm design is made using 3D printing and uses regular servos for each joint, which keeps the cost low and makes it simple to build. The design includes printable parts for the base, rotating platform, arm sections, and a robotic arm gripper, all of which fit together using basic screws. The arm can move in multiple directions, making it good for simple pick-and-place activities. Its easy setup is perfect for people who are new to building robots. The project comes with full STL files and detailed instructions, so anyone can print the parts, attach the servos, and get the arm up and running without needing special tools. The straightforward mechanical design and simple servo control make this an ideal first project for newcomers who want hands-on experience with robotic arm 3D models, basic kinematics, and servo programming without getting overwhelmed by complex control algorithms or difficult assembly procedures.

Project Source: Printables - DIY Robotic Arm Model.
Original File Link: https://www.printables.com/model/41837-diy-robot-arm 

9. Simple 3D-Printed Servo Robotic Arm - Practical Learning Platform

Beginner-friendly 3D-printed robotic arm using SG90 and MG995 servo motors for reliable pick and place

This completely 3D-printed  robotic arm for beginners is a great project for beginners and has real-world use. It uses SG90 and MG995 servos, which provide enough power for simple pick-and-place activities. All the parts are made using a 3D printer and can be put together easily with just basic screws-no special tools are required. The arm is controlled by an Arduino, allowing for smooth movement based on angles. It also comes with STL files and wiring instructions. This project is perfect for those who want to learn about mechanical design, servo control, and multi-axis motion without spending a lot of money. It strategically employs a combination of SG90 servos (lightweight, low-cost) and MG995 servos (higher torque, metal gears) positioned according to load requirements—demonstrating proper servo selection principles that apply to all robotic arm projects.

Project  Source: YouTube Creator (Channel Name: Emre Kalem).
Original Video Link: https://www.youtube.com/watch?v=CHV36hu9z3E

10. 3D Printed Arduino-Based Robotic Arm by BasementMaker

3D-printed 6-axis robotic arm with multiple servo motors mounted on stable base and controlled by Arduino Mega

The BasementMaker DIY 3D printed robot arm is a completely open-source project that brings together 3D-printed components with an Arduino Mega and regular hobby servos to make a smooth and dependable six-axis robotic arm. It was designed after several improvements to enhance its strength and movement performance. The arm includes a strong printed base, several rotating joints, and a working robotic arm gripper, which makes it perfect for simple pick-and-place tasks. All the STL and STEP design files are available for free, along with detailed step-by-step guides for printing, building, connecting the electronics, and programming. It's perfect for serious beginners ready to tackle a comprehensive 6-axis robot arm project with professional-grade documentation.

Project Source: Instructables-3D-Printed Arduino-Based Robotic Arm
File Link:https://www.instructables.com/3D-Printed-Arduino-Based-Robotic-Arm/

If you’re interested in a mobile version of a pick-and-place system, you can also explore our Bluetooth-Controlled Pick and Place Robotic Arm Car project

Comprehensive Comparison: Top 10 Robotic Arm Projects

The table below summarises the key features of all 10 open source robotic arms projects covered in this article, making it easier to compare their controllers, DOF, build type, & suitability, etc.

S.NOProject NameController
Used		DOFBuilt-TypeMotorControl MethodSuitable For
1Object Following Robotic ArmArduino UNO R34 DOF3D-printedSG90 Servo MotorsArduino
-based sensor control		Object tracking, basic automation,learning robotics.
2Robotic Arm using LPC2148ARM7 LPC21484 DOFLightweight mechanical buildSG90 servosPotentiometer manual controlLearning ADC, PWM, embedded control
3Dolphin 3D-Printed Robotic ArmArduino/Similar4 DOFFully 3D printedStandard hobby servosBasic Arduino controlNew makers wanting simple, stable motion
4ESP32 Smartphone/Web-Controlled 4-DOF ArmESP324 DOFLightweight, likely 3D-printedHobby servosWeb UI sliders + Record/PlayWireless control learning
53D-Printed 6-DOF Arduino ArmArduino UNO6 DOFFully 3D printedMultiple servo motorsArduino angle controlIntermediate users wanting complex motion
6DIY 6-DOF Arduino Robot ArmArduino UNO6 DOF3D-printedMixed servosArduino PWMAdvanced hobby projects & experiments
7STM32 Robot Arm with Smartphone ControlSTM32F103+ESP326 DOFMixed 3D-printed + custom PCBMG995 + SG90Smartphone App (Bluetooth)Embedded systems learners
8DIY Robotic Arm (Printables)Arduino UNO/Similar5 DOFFully 3D-printedHobby servosBasic servo controlBeginners with 3D printers
9Simple 3D-Printed Servo ArmArduino UNO5 DOFFully 3D printedSG90 + MG995Wired Arduino controlMechanical design & servo basics
103D Printed Arduino Based Robotic ArmArduino Mega6 DOFFully 3D-printedMix of hobby servos: MG996R / MG90S / SG90 / SG5010Button-based manual control using Arduino Servo libraryBeginners learning robotics, servo control, and 3D-printing projects

Real-World Applications of Robotic Arms

Understanding where robotic arm designs are deployed in industry and research helps contextualise your learning and reveals potential career paths in robotics engineering and automation technology.

  • Industrial Automation: 
    The robotic arms are widely used in welding, painting, packaging, and assembling products. Industrial robotic arms form the backbone of modern manufacturing facilities, performing repetitive tasks with precision, speed, and consistency that human workers cannot match. 
  • Medical and Surgical Assistance:
    These will assist in precise surgical procedures, rehabilitation, and handling delicate medical tasks that require stability and accuracy. Specialised 6-axis robotic arms assist surgeons in minimally invasive procedures requiring extreme precision and stability.
  • Laboratory Automation:
    Robotic arms can able to handle the test tubes, samples and looped lab tasks, which also helps in reducing human error. Pick and place robotic arms automate repetitive laboratory tasks: pipetting samples, handling test tubes, preparing microtiter plates, organising specimens, and executing standardised protocols.
  • 3D Printing and Fabrication:
    Advanced arms are used in additive manufacturing, printing large or complex components with precision. Advanced robotic arms enable large-scale additive manufacturing by printing complex components layer by layer. 
  • Agriculture:
    They help in sorting, planting, harvesting, reducing the labour cost and improving the overall efficiency. Specialised robotic arm grippers adapted for delicate produce enable automated harvesting, sorting, planting, and packaging operations. 
  • Hazardous Environment Operations:
    Robotic arms can perform tasks in dangerous environments, such as handling chemicals, explosives, or radioactive materials, keeping humans safe. Remote-controlled industrial robotic arms perform dangerous tasks in environments hostile to human workers.
  • Education and Research:
    They are excellent tools for learning robotics, automation, and programming, giving hands-on experience with real-world applications. Affordable robotic arms using Arduino and 3d printed robot arms serve as excellent educational tools, providing hands-on experience with robotics principles, automation fundamentals, programming concepts, and engineering problem-solving.
  • Food Industry:
    Used for sorting, packaging, and handling food items in hygienic conditions, improving speed and reducing contamination. Food-safe robotic arm designs automate sorting, packaging, decorating, and assembly of food items in hygienic conditions.

Frequently Asked Questions About  Robotic Arm Projects

⇥ 1. Are all these robotic arm projects open-source?
Yes, every project which is listed here is Open-Source and you can able to download code,3D design files, etc..all for free.

⇥  2. Do I need a strong background in robotics to build these arms?
No. Most of the projects are designed with beginners. If you follow the steps carefully, you can also build a fully working robotic arm with the basic knowledge of servos, microcontroller and simple mechanical knowledge.

⇥  3. What kind of materials are used to build these robotic arms?
Many of the Robotic arms use the 3D-printed parts with the servos. Some of the arms use Acrylic sheets or ready-made brackets.

⇥ 4 . Which microcontrollers are often used in these projects?
The common controllers which are all used in the above robotic arms are Arduino UNO, Arduino Mega, ESP32, NodeMCU, STM32, etc.

⇥ 5. How many degrees of freedom do these robotic arms have?
Most beginner-level arms range from 3 to 6 DOF. More DOF means the arm can move more freely, but it also requires more motors and wiring.

⇥ 6. Can I build these arms without a 3D printer?
Yes. Some projects use acrylic or standard servo brackets that don’t require any printing. But having access to a 3D printer makes the build easier and lets you customise parts.

⇥ 7. What basic tools do I need to assemble a robotic arm?
A Set of screwdrivers, a small soldering iron, and, in some cases, a 3D printer to make the 3D models. Mostly, the listed Robotic Arms don't need any special tools.

Conclusion For the Top 10 Robotic Arms

Open source robotic arm designs make it easy for anyone to explore robotics without needing advanced experience or expensive tools. With ready-to-use robotic arm 3D models, schematics, and code, beginners can understand how joints, servos, and different control systems work by actually building and experimenting.  Explore wireless ESP32 connectivity, or master multi-axis coordination with a complete 6-axis robot arm project.  The robotic arm projects listed in this article offer a solid starting point, whether you want to learn basic movement of a pick and place robotic arm, practice 3D printing, or explore multi-axis control. These robotic arms, using Arduino and similar microcontrollers, not only teach fundamental concepts but also encourage experimentation, modification, and innovation. The DIY 3D printed robot arm that is mentioned will not only encourage you to learn, but it will also help you to improve and create your own design. If you're interested in how robotic arm designs are being used in real industrial applications, you can also explore our interview on STMicroelectronics’ STM32MP2 AI Robot Demo at Electronica India 2025.  Every industrial robotic arm engineer started somewhere, and these beginner-friendly robotic arm DIY projects provide the perfect foundation for your robotics journey. 

Previously, we have built many interesting projects on a robotic arm. If you want to know more about those topics, links are given below.

Hand Gesture Controlled Robotic Arm using Arduino Nano

Hand Gesture Controlled Robotic Arm using Arduino Nano

In this DIY session, we will build a Hand gesture-controlled robotic ARM using Arduino Nano, MPU6050 Gyroscope and flex sensor.

Robotic Arm Control using PIC Microcontroller

Robotic Arm Control using PIC Microcontroller

Control a multi-servo robotic arm using the PIC16F877A microcontroller by generating PWM signals on GPIO pins, reading potentiometer inputs, and driving servos with timer interrupts in a hands-on embedded systems project.

How to build a Simple Arduino Robotic Arm

How to build a Simple Arduino Robotic Arm

In this tutorial, we design an Arduino Uno Robotic Arm. This Robotic Arm can be controlled by four Potentiometers attached to it, each one used to control a servo motor.

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