Again rather progress (made) FOR ME than by myself. I love it! I’ll post a pic in the kosmo-setup thread once it reached its destination and is wired up…
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As I mentioned way back in the summer, my next module was indeed a combined frequency divider / analogue switch module.
Although it was primarily intended for use with my 2 channel ADCequencer module I built it to be as versatile as possible. It has four divide by 2 stages which are normalled together so single clock input to CLK1 gives divisions by 2, 4, 8 and 16 on the four DIV outputs, but it can also be used to give smaller divisions of more than one clock if needed. There are also three analogue change-over switches, each of which can be controlled by any of the DIV outputs. It works a treat with the sequencer module and allows some variation of the sequence by adjusting the relative phase of the sequencer and the frequency divider. Full details are on GitHub. Together with an additional (slender!) mult, this has filled my second cabinet.
But of course I couldn’t stop there 
. I was intrigued by the Nonlinear Circuits Cellular Automata module which is a real tour de force of logic circuit design. While I admire the ‘no computer’ ethos, it is an extremely complicated way to implement something which can be emulated very easily by a microcontroller, so here is my version - Cellular Automaton (there is only one of it) - based on an Arduino Pro Mini.
Of course it’s not just a straight copy - all those analogue inputs on the Arduino allow some very interesting additional functionality, most particularly the ability to have probabilistic control of the cellular automaton. The same rules are used as in the original and are applied to the cells in the current generation. Cells which the rules say will be OFF in the next generation will indeed be OFF, but a voltage controlled probability will be applied to potential ON cells to deternine if they actually will be ON. A 0V input applies a low probability increasing to 1 with an input of 5V or above. Similarly the seed inputs accept analogue signals giving probabilistic control over the off-grid seed cells, and there’s an additional input which applies a probability to all the seed cells together. Finally there’s the possibilty to use an external clock or a voltage-controlled internal clock. The P(surv), P(seed) and CLOCK inputs are all normalled to 5V so the module can be used without any external inputs. The probability controls allow control of the density of ON cells in the grid and also significantly increase the randomness of the patterns.
The 16 gate outputs are at 6V, and there are three pseudo random CV outputs as in the Nonlinear Circuits original, though the absolute voltage levels are probably different. Once again, full details are on GitHub.
Hope these may be of interest!
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Marvelous! Well done.
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My most recent addition to my case is a 30cm drum section:
- 4 channel gate/trigger sequencer: based on Benji Jaio’s design, expended from 3 to 4 channels, added gate outs);
- Snare: Soundforce 808 Snare PCB;
- Kick: Soundforce 808 Kick PCB;
- LMNC 2700 Twin T drum: work in progress, hum/oscillation in Kik/HBongo/mix to address).
Really happy with these additions to my case!
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Parker-Steiner VCF with low-pass, band-pass and high-pass modes.
It’s a Yusynth circuit, plus some useful insight from Eddy Bergman. Thank you both.
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Finally got around to making something I’ve intended for a while: A bench headphone amp.
It uses one of these TDA1308 modules along with an op amp input stage to reduce a synth level signal to make the output safe for headphones. The latter built on stripboard (and yes, I am reminded how much I dislike stripboard), and it’s kind of kludgey because I’d originally built it to use USB power and then was reminded of how noisy USB adapters are at audio frequencies — or at least the one I was using is — so I had to squeeze in a 5V regulator to use with a 9 V battery (that or use 3 AAs, and I hate AAs). And a switch, and an indicator LED to lessen the chances of leaving it powered up and draining the battery. Shoved into a 3D printed box.
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Good job! Sounds awesome!.
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yay done and working / calibrated .
now on to spend as much time reshuffling the rack to fit it in as I did building it .
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well ok it started out as make room for one module and ended up a rack rebuild lol .
blank slate time to design and build .
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Build up like music. Start with rhythm then move on through the voices, filters and FX.
Just remember your final case will need twice the space. 
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Hey Rich - could you post a circuit diagram or a picture of your stripboard? I’m interested in making something like this too. Particularly on adapting the synth level signal…
Thanks!
The stripboard layout is rather a mess for the reasons I mentioned, but the schematic is something like this:
I would have put another cap on the input to the voltage regulator (per the datasheet) but there wasn’t room. Choose a value for R1 for desired LED brightness; I used a 33k with a high efficiency (“super bright”) LED to minimize battery drain.
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These modules are quite neat and I too have been experimenting with them. However, I ended up changing some components to improve the frequency response as the output caps create a high-pass filter with the headphones.
I changed C1 and C2 input caps to 22u and R5 and R6 to a 220n cap + 8k resistor parallel with 470k resistor to get more flat response with my HD560S Pros (120 ohms). These values will naturally be different for headphones with different impedance. Most likely the module was the same one you used, there aren’t many different designs out there.
Additionally, I was using a 10k pot for adjusting the input, so the response probably is different with an opamp driving the chip.
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If one is building the circuit as a headphone output module instead of a bench amp, they could consider a single supply rail-to-rail op amp like TLV2462 instead of the LM358.
Given how much attenuation is needed, rail to rail isn’t required. I think the LM358 with single 5V supply works fine for this.
How about sound fidelity? I always thought LM358 are terrible for anything audio. Assuming, of course, one would like to have some fidelity in such a module.
I’m working on a step sequencer which uses 16 pots for CV voltages. I’ve added a voltage reference to keep the voltage feeding the pots constant. Within limits I can now set the maximum output voltage. However, I’m not sure about choosing the maximum voltage. In my experiments I have it set to 7 Volts, so that it can span 7 octaves. But in actual practise, it is not easy to set the pots to the right value not even when using a quantiser because every tiny bit of rotation will change the tone (making the range will make this worse). And you can only use it with very stable oscillators that are capable of working with such a large voltage range. So there is the dilemma: if the voltage range it high, the output can span many octaves, but this makes it difficult to choose the notes. If the range is small, the output may span too few notes. What have you used in your sequencer? Voltage ranges using a switch?
Yeah that’s a massive swing on a pot 7*12 steps, 84 positions, most sequencers use 1 octave or maybe 2, some have fine controls, some have octave switches. I’ve not seen one that can span 7 octaves.
Just add I built the electric druid VCDCO which has 32 waveforms on the wave CV, it was impossible to select a waveform consistently in the pair of DCOs, I actually swapped the 10k pots out for multiturn pots, you might want to consider this if you stick with anything over a 3 octave range.
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