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3 thoughts on “Waveform Generator

  • Hi, Tyler,

    I thought I’d try out the waveform generator while I’m waiting for the next installment in your YM3812 series. I’m having some trouble getting this to work, and I’m wondering if it has something to do with my not powering the op-amps correctly…I’m applying 5v at pin 8 and connecting pin 4 to ground…is that correct? If not, how are you powering all of the TL072s? I’ve been reading up on op-amps, but I have to admit my knowledge there is pretty shaky. Also, if I don’t have a 20k resistor for R5 in the clipping circuit, I can just substitute 2 10k resistors in series, right?



    • Hey Peter! I think you are correct. The issue is probably how you are powering the op amps. I ended up using +12v on pin 8 and -12v on pin 4. (Realizing now that I left this out of the schematic—-woops!) If you don’t have a bipolar power supply, it might be possible to rework things using just +5v, but then you will need to connect the + input of the op-amps to a “virtual ground” of 2.5v. Also, you’d probably need a different op-amp that supports voltages closer to the VCC/VDD rails like a OPA2604. Probably the easiest thing to do would be to just use +/- 12v on the OpAmps if you can. As for the 20k resistor, 2x10ks in series would definitely give you 20k. But honestly, I’m not sure how critical the exact value is. You can always try a 10k and see if that just works. Best of luck!

  • Thanks for your reply, Tyler!
    What bipolar power supply do you use for the +/-12v? Would a DC +/- buck-boost converter do the job?
    Would a 22k resistor be a suitable replacement for the 20k?
    Did you use your BeatStep to generate the control voltages in the video?

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