Voltage Doubler Circuit

Voltage doubler is the circuit where we get the twice of the input voltage, like if we supply 5v voltage, we will get 10 volt at the output. Generally transformers are there to step-up or step-down the voltage, but sometimes transformers are not feasible because of their size and cost. So here is the quick, easy and practical solution to double the voltage, using 555 timer IC.

 

Components

  • 555 timer IC
  • Diodes -2 (1N4007)
  • Resistors- 10k, 33k
  • Capaciotors- 22uf (2),  0.01uF (2)
  • 3-12v Power supply source

 

Voltage Doubler Circuit Diagram & Explanation

We can divide the circuit into two parts, first part consist the 555 time IC in Astable mode, to generate the square wave and second part consist 2 diodes and 2 capacitors to double the output voltage.

Voltage Doubler Circuit Diagram

We have configured 555 Timer IC in Astable multivibrator mode to generate the square wave of approx. 2KHz, this frequency is decided by the resistor R1, R2 and capacitor C1. Below is he formulae for the same:

F = 1.44 / (R1+2*R2) * C1

When the output at PIN 3 of 555 IC is low, Diode D1 get forward biased and capacitor C3 get charged through the D1. Capacitor C3 get charged up to the same voltage at the source, in our case 5v.

 

Now when output at PIN 3 goes high, D1 get reverse biased and blocks the discharging of the capacitor C3, and at the same time D2 is forward biased and allow the capacitor C4 to charge. Now the capacitor C4 charges with the combined voltage of Capacitor C3 and the input source voltage, means  5v of capacitor C3 and 5v of input supply, so it charges up to 10v (twice the voltage of input source). But in practical we get output voltage less than the twice of input voltage, like in our case we get approx. 8.76v instead of 10v.

 

There are also some disadvantages of this voltage doubler circuit:

  1. However this circuit is very useful to generate higher voltage from a low power source, but this can only deliver up to 50mA current. So it should only be used for low current driven applications.
  2. Also the output voltage may be unstable, so a voltage regulator (IC78XX) of proper rating can be used regulation and smooth output. But voltage regulator IC itself consume some current, and reduce the deliverable current (must not exceed 70mA).

 

Notes:

  • Input voltage should be between 3-12 volt, higher voltage will destroy the 555 timer IC.
  • The load at output should not draw more than 70mA current.
  • Voltage wont double instantaneously but it will increase slowly and after some time, it will set to the twice of input voltage.
  • The voltage rating of capacitor C4 should be at least twice the input voltage.
  • The output voltage is not exactly the twice of input voltage, it will be less than Input voltage. Like we got 8.76v for 5v input supply and if you apply 12v, output voltage would be 18-20 volt. 
Video: 

Comments (9)

  • ganeshraj's picture
    ganeshraj

    i got only same input voltage. i did this multiple times.

    Nov 26, 2015
  • Abhishek's picture
    Abhishek

    Please recheck your circuit and connections, also measure the voltage between specified points.

    Nov 28, 2015
  • steve's picture
    steve

    i got more than twice for 12v input i got 27.44volts

    Mar 02, 2016
  • Hariharan.K's picture
    Hariharan.K

    Wow!
    Its Working Exactly ...

    Mar 16, 2016
  • raviteja's picture
    raviteja

    its really simple circuit i got output tnqqqqqqqqqq

    May 06, 2016
  • arun's picture
    arun

    to increase voltage which is ic is used and we can increase

    Jul 27, 2016
  • Max's picture
    Max

    Hi
    This looks like a good circuit.
    I just have a couple of questions:
    1. Are pin 3 and pin 7 connected between R1 and R2?
    2. Is pin 6 connected to pin 1 and pin 2?
    3. If so, then C1 seems to be short-circuited.
    4. All the other connections have a dot to show connectivity, but not those.
    Thank you
    Max

    Aug 19, 2016
  • Maddy's picture
    Maddy

    Answers to your questions:
    1. No
    2. Pin 6 is connected to Pin 2 but not with Pin 1.

    yes you are right dots are missing at some connections.

    Aug 20, 2016
  • Vishal Jadhav's picture
    Vishal Jadhav

    The circuit given and the process is absolutely correct. The output received by my team was exactly double of my input voltage. Thank you.

    Sep 04, 2016

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