With inexpensive microntrollers capable of the most impressive feats of sound synthesis, it’s not so often we see projects that return to an earlier style of electronic music project. The 1-bit synth from [Electroagenda] takes us firmly into that territory, employing that most trusty of circuits, a 555.
It’s a time-honored circuit, a 555 provides a note clock that drives a 4017 that functions as a sequencer. This switches in a set of voltage dividers, which in turn control another 555 oscillator that produces the notes. It’s a fun toy straight from the 1970s, right down to the protoboard and hookup wire construction. There’s a demo video with some lovely beeps below, and we think most of you should have what it takes to make your own.
If you’re seeking more inspiration, may we introduce you to our Logic Noise series?
The sequencer should be 8, 12 or 16 steps. Not 10.
Why ?
What for?
Because most music uses groups of 3 or 4 notes. Having 12 steps allows for 2/4, 3/4, 4/4, 3/8, 6/8, 12/8 time signatures.
12 is very, very nice for this, because of the compound meters you can get (as yopu mention 12/8) to emulate things like triplets, though no polyrhythms at that few steps.
Actually, thinking about it, you could still do polyrhythms as long as you can adjust the tempo to be fast enough to, say, let all 12 steps be a single beat.
Doesn’t answer the question though.
I guess his comment makes more sense if you’re more familiar with music. If you’re sequencing musical triggers, since music is typically in groups of 3 or 4, you can sequence things that correspond to actual music. Since neither 3 nor 4 divides 10, you cannot as nicely do this with a 10 step sequence, and you can, at most, consider a single beat per 10 steps, with a single even subdivision, whereas music typically has subdivisions continuing on and on that follow powers of 2.
For instance, “common time” in music is in something called 4/4. The important part here is that there are 4 even beats in one measure. There’s no way to evenly put 4 beats into a grouping of 10, but you can evenly put 4 beats into a grouping of 12. You can do better with a group of 16, as you can do a full measure of 16th notes.
10 steps allows you to do 10 count timings which exist. 5/4 or 10/8 are valid time signatures. Venetian snares music is 90% of the time in 7/8.
Sure, but the vast, vast majority of music is not like that. Even the category of asymmetrical time signatures is tiny, let alone the subset of that would fit in a count of 10.
Apart from wondering why, the 4017 is a decade counter, 10 outputs. So it’s 10 steps maximum (it could be 8 by feeding back an output to the reset input )
Right? The thing is called a “decade counter” for a reason.
But if you want to make a puny octal counter (which is totally more musically useful) take the output from the 9th beat, feed it into the carry in of the next 4017 in the chain.
A circuit that was much used to create multi-tone or Morse “roger beep” circuits for CB radio, nice to see it again
I think there was a 73 magazine article about that. Searching archive and worldradiohistory results in a list of several issues with such circuitry.
I remember piecing together similar circuits found in Forest Mims publications when playing with logic as a youngster. This is classic and a fantasticly fun way to get people excited about practical electronics with building blocks of popcorn chips. Makes me want to get the old logics parts bin out again. Thanks for the inspiration!
Probably the oldest toy sequencer design too !
I’ve already seen the same 4017 + 555 set more than 40 years ago.
Sounds like a Game and Watch.
lol! I built this as a child! But I used a 7490. I got it from Radio Shack, and I also learned a lesson in that their chips were often factory seconds, and it didn’t work until I replaced it. So I learned a little debugging in the process, too.
Could have used an Arduino. ;)
It’s a cute toy, but pretty limited. I have a PAiA analog sequencer from the late 70s, which outputs a control voltage and a trigger to control analog synth modules, so there’s more capability there, but even with that, it’s just cumbersome and limited compared to what can be achieved with a computer-based sequencer and MIDI-controlled synths (analog or digital).
I do think a microcontroller-based stand-alone sequencer (with analog control voltage and/or MIDI out) would be quite useful. I imagine some already exist, and designing one from the ground up would be a fun challenge.
Step sequencers run at clock speeds which are in the audible range can be used as waveshapers too. The waveform is shaped by each steps voltage, allowing you to draw the waveform.
The bank of pots used in the early VCR’s for tuning would very good to use here. They came in 12 or 14 usually. I’ve some stashed away for this kind of project. I’d rather go with voltage control out for my ARP. Berlin School!
so is it time for a similar chip to the 4017 that can go to 16?
or even better, a 4017/555 combination chip?
PAiA 4780 Sequencer Module
https://modularsynthesis.com/paia/4700/4780/4780.htm
Close Encounters of the Third Kind
I recall making that 5 or 6 note bleeper with lights. Was very impressive at the time.
Practical Ele tronics published a more sophisticated take on this design in the 70s. IIRC it had a sequence length switxh that allowed steps 2 to 10 to be used tk trjgger the reset lin of the 4017. Instant solution?
Yup! Reset or carry to the next chip. It’s just logic. :)
I’ve made a similar minimalistic sequencer, check it out :) https://www.youtube.com/watch?v=cwCcLHB66bs
At one time, It sounded like Baba O’riley of the Who was going to start.
https://youtu.be/x2KRpRMSu4g?t=22