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MAKE contributor Michael Una cooks up some particularly head-bobbing beats with help from an old arcade sound effects chip (plus a 4017 sequencer). The SN76477 “complex sound generator” IC is best known its work in Space Invaders arcade cabinets – the chips’ onboard LFO, VCO, and noise generator combine to produce all manner of blippy goodness. The bad news is it’s no longer produced :( Though some surplus and rare-chip sellers have them from time to time.) So if you do score one, a drum machine project sure seems like a worthy home!


25 year old box of sounds

Collin Cunningham

Born, drew a lot, made video, made music on 4-track, then computer, more songwriting, met future wife, went to art school for video major, made websites, toured in a band, worked as web media tech, discovered electronics, taught myself electronics, blogged about DIY electronics, made web videos about electronics and made music for them … and I still do!



  1. jeff-o says:

    I’d love to see a schematic for that drum machine! I have one of those chips kicking around…

  2. Michael Una says:

    Heya Jeff-O, I’m working on it. I need to get my logic controls for beatmaking up and running, but I’ll make sure a schematic gets published here.

  3. jeff-o says:

    Awesome! :D

  4. crackhead says:

    Found this info on a site about repairing old video games:

    Looking for a 76477 ? They are now at BGMicro look for part # ICS76477, but they are the wrong package type so you will have to adapt.

    I haven’t actually looked to see if I could find one or to see if it truly is the same chip.

    1. Collin Cunningham says:

      Totally, we posted that source awhile back via @make on twitter. I ordered a few and yes they work fine – though the pins are a slight pain. Cool, they still have em in stock – I’ll update the post aaccordingly

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