7400 drum machine is a delight

[74hc595] just finished his entry in the 7400 logic contest. It’s a drum machine built entirely from 7400-series logic chips. He hasn’t quite reached full completion of the project yet. The hardware works just fine, and he’s built a foam core face plate with many more controls than you see here but much of the circuit is still on a breadboard at this point and only two of the channels have been complete thus far.

Jump to the video clip after the break to get the details of how the system works and to hear it in action. This demonstration is one of the best we’ve seen for a synthesizer project as he actually talks about what each control does, and how that is accomplished with the hardware. We’re not going to go into detail about the circuitry he’s designed. As we said before, it uses 7400 logic but also sources a 555 timer to keep the beat. The page linked above has a PDF of the schematic available and you could really lose a lot of time studying how he did this. We might even try to build it in a simulator to see what we can learn.

24 thoughts on “7400 drum machine is a delight

  1. Is he selling these? He could EASILY kickstart this and make some money.

    Especially if the system sold was modular – buy sound generators for each channel (and they don’t have to be “drum”; they could be “bass machine” type); the sequencer; etc.

  2. Thanks guys! (I’m the creator)

    Turning it into a kit would be a very cool idea–especially as a modular system–but I’d use an AVR for the sequencer. Some of the parts (esp. the 74C922 and 74LS189) are prohibitively expensive and not available in quantity. If I made a nice case with slots for plug-in modules it could be sweet.

    I couldn’t find any simulation software up to the task, I just built it on the fly using datasheets and a logic analyzer. Logisim is promising, but doesn’t supoort the full line of 74xx chips, and seems buggy. I used Paul Falstad’s circuit applet to design and simulate the sound generator though, that worked pretty well.

    1. Very inspiring work! Being an Arduino guy this boggles my mind, but i guess that’s why these competitions exist – to remind us what can be done with more basic IC’s?

      Good work!

    2. Hey, can you link to the Falstad circuit you used for the sound generation? I’m interested in waveform shaping and think it’d be pretty interesting.

      Thanks!

  3. Really nice project. This is what I thought of when I saw the contest. Basically a little Subtractor drum synth from Reason.

    I like this the best of any I have seen so far simply because of the fact the end product is actually a nice useful piece of equipment.

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