This Synth Is Okay

While this 3D printed synthesizer might just be okay, we’re going to say it’s better than that. Why? [oskitone] did something with a 555 timer.

The Okay synth from [oskitone] uses a completely 3D printed enclosure. Even the keys are printed. Underneath these keys is a small PCB loaded up with tact switches and small potentiometers. This board runs to another board loaded up with a 555 timer and a CD4040 frequency divider. This, in turn, goes into an LM386 amplifier. It’s more or less the simplest synth you can make.

If this synth looks familiar, you’re right. A few months ago, [oskitone] released the Hello F0 synth, a simple wooden box with 3D printed keys, a few switches, and a single 4046 PLL oscillator. It’s the simplest synth you can build, but it is something that can be extended into a real, proper synthesizer with different waveforms, LFOs, and envelope generators.

The sound of this chip is a very hard square wave with none of the subtleties of A,S,D, or R. Turn down the octave knob and it makes a great bass synth, or turn the octave knob to the middle for some great chiptune tones. All the 3D models for this synth are available on Thingiverse, so if you’d like to print your own, have at it.

You can check out the demo of the Okay synth below.

18 thoughts on “This Synth Is Okay

  1. Also, I see [Brian Benchoff] has called the 555 a *timer*

    I seem to remember that it had several descriptions for example

    programmable timer
    astable timer
    multi-mode timer
    multi-mode multi-vibrator

          1. Well google, so I’d reverse image search it for a saucier sauce, because it didn’t necessarily come from a page with circuit description and build/design notes.

          2. Amusingly, just searching for the model of transistor — a UJT — is enough to find that it’s from the pamphlet that Forrest Mims wrote for Radio Shack called Electronic Music Projects.

          3. A lot of times they are referred to as transistor “organs” so you may want to go that way. Synths came later though they are all the same thing at the end of the day. Lots of early kits have you build one of these.
            Here is a similar one that a quick GIS of transistor organ brought back. Similar to that one.
            I will warn you though they sound very buzzy and sharp. Adding vibrato helps only a little lol. Good luck with your journey, Olsen :)

          4. Right, really depends on how many stages you wanna stack up for envelope shaping for quality of sound, but then you may as well put knobs in those too and make it a synth.

        1. The 555 is often used like a unijunction transistor, and I assume the UJT mostly disappeared because the 555 did the same things. In that organ the output will be short pulses, while the emitter will show a ramp, just as the 555 will show a ramp across the timing capacitor, and then narrow pulses at the output.


  2. Good to see things progressing. Nice printed case :) Is there any particular reason each key needs a tuning pot? Could you not just do a standard resistor value key layout with a master tuning pot on the end?
    Kudos and keep up the good work :)

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