I want to use a control voltage to generate a PWM signal that will drive a DC motor. I can't use a potentiometer with a 555 timer as I have to control it from National Instruments LabView software with a voltage output.

  • 1
    \$\begingroup\$ Welcome to electronics.stackexchange. Is this homework? Can you edit your question to show a conceptual block-diagram of what you want to achieve? \$\endgroup\$ Sep 18, 2013 at 10:31
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    \$\begingroup\$ If you have to control it from software, forget the control voltage and generate PWM directly. \$\endgroup\$
    – user16324
    Sep 18, 2013 at 11:12
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    \$\begingroup\$ Use a micro-controller. \$\endgroup\$
    – Enthusiast
    Sep 18, 2013 at 13:01

2 Answers 2


If you have a suitable voltage output that you can control you can hook that up to a 555 instead of using a potentiometer.

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If you read the 555 data sheet, you can find out what is required on the modulation input.


I have made a proof of concept for an ATtiny13 microcontroller once. The code can be found here.

Basically what the program does is read the top eight bits of the ADC (pin 3) and convert that to a PWM signal (pin 6). All you need is a microcontroller (ATtiny13 or similar AVR) a 5V power supply, a capacitor to decouple the power supply and a programmer... For the programmer I personally use a spare Arduino, which brings me to the other option: Use a small Arduino.

  • \$\begingroup\$ What, you have something against big Arduinos? :-) \$\endgroup\$ Sep 18, 2013 at 19:32
  • \$\begingroup\$ Not at all @AnindoGhosh, but it isn't necessary to spend more money than necessary, hence my ATtiny proposal. \$\endgroup\$
    – jippie
    Sep 18, 2013 at 19:39
  • \$\begingroup\$ Thanx jippie i am very much comfortable with your suggestion regarding ATtiny 13. \$\endgroup\$ Oct 1, 2013 at 10:31
  • \$\begingroup\$ @ghosh sir i have done it with arduino but i want some cheap method for it \$\endgroup\$ Oct 1, 2013 at 10:35
  • \$\begingroup\$ @vishantKumar define "cheap" \$\endgroup\$
    – jippie
    Oct 1, 2013 at 16:13

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