Since the last time I made something synth related (this Atari Punk Console inside an alarm proximity sensor case - my first approach to this world, btw) I've been interested on knowing more about the electronics behind all those full synths and modules people made and share.

Following that idea, I've poked around, read a lot and watched some cool videos from people that really know what they're doing (exactly the opposite as me! : D) until I finally made one of those "classic" sequencers according to the Internet: a 4017-based Baby-10-like attached to an Atari Punk Console.

There are three main parts on the device:

  1. A 555 timer in astable mode that generates a rising edge on a regular basis (the period can be modified with a potentiometer the user can control). This is our clock signal for the sequencer.
  2. A CD4017BE decade counter that enable up to 10 different "outputs" each time the clock signal rises. This outputs are attached to 10 different potentiometers, so each one can be adjusted separately.
  3. An Atari Punk Console (made with two more 555 timers). The first variable resistor is actually a direct connection to the 10 outputs from the counter (there's a diode on each one to made it work without "conflicts"); so each time the clock triggers a change, the value of that resistor changes too (or not, it depends on the knobs position!) and the sound generated by the APC becames different.

There's also a knob for the second potentiometer in the APC (but this will be the same for all the different outputs) and a bunch of switches to force a reset in the decade counter - this will allow the sequence to "end" before the 10th output, once the switched one is triggered.

Some of its features (or things I like about the device)

Things that went wrong / things I need to fix / things interestingly enough to mention / TODO ?

In conclusion

Not the best sequencer you can find out there and I hope not the best I can make, but it worked pretty well as a second synth project after my first Atari Punk Console. As usual, lots of mistakes were made, most of them were succesfully fixed and there're a few that remains for the next iteration or next device (not sure if I will re-build this one or move on to a different one with all the learned things here).

See (and listen) the synth!

Here's a video from my Twitter account with the synth running and making sounds (needless to say, I'm not an expert on those "make cool music and/or sounds", so this is more of a proof of concept video rather than "real music").

Links and extra info