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In order to get the PWM signal out of a sawtooth (ramp up/down) I usualy use an operational amplifier and set the reference value with a potentiometer. This is how I can then modify the PWM by turning the potentiometer.

Is it possible to get a PWM signal out of a triangle signal using operational amplifier in a similar way?

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  • \$\begingroup\$ Not sure what you are asking. Why would it be any different with a triangle than with a sawtooth?. \$\endgroup\$
    – jippie
    Commented Aug 31, 2013 at 17:10
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    \$\begingroup\$ Yes. A triangle wave will also work. Heck, even a sine wave will work but the control signal from the pot will have a non-linear relationship with the PWM duty cycle. \$\endgroup\$
    – user3624
    Commented Aug 31, 2013 at 17:21

2 Answers 2

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Yes. The difference is that the PWM pulse will be centered within the train rather than against either edge (type 1).

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  • \$\begingroup\$ Thank you. Are there any schematics for how to achieve this? \$\endgroup\$
    – 71GA
    Commented Aug 31, 2013 at 18:00
  • \$\begingroup\$ On what? How to generate a triangle wave, or on how to use it for PWM? \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Aug 31, 2013 at 18:06
  • \$\begingroup\$ How to use it for PWM. \$\endgroup\$
    – 71GA
    Commented Aug 31, 2013 at 18:10
  • \$\begingroup\$ Given your initial question, I'm not really sure how you want me to answer that... \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Aug 31, 2013 at 18:11
  • \$\begingroup\$ I have a triangle signal on input of a blackbox which outputs a PWM signal. What kind of a circuit must this blackbox be? \$\endgroup\$
    – 71GA
    Commented Aug 31, 2013 at 18:18
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It's the same thing. Whether the leading edge is nearly vertical (sawtooth) or about the same slope as the other edge (triangle), makes no difference in a comparator producing a linearly varying duty cycle as a function of the reference voltage.

Draw it out and think about it.

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