MonoMiK

Finally, i found the time to complete my ADSR modules. They were the first module working perfectly directly after soldering them together, i didn't forget any wires or so. Maybe due to the very compact layout i just took more care on this. The only imperfection was a bug in the schematics, 2 swapped resistor values. This is the reason why i always build the modules and test them before releasing the schematics.

I'm very happy with the performance, attack time can go down to fantastic 30 microseconds, the official range starts at 100 microseconds - 0.1ms. Due to the exponential control of the timing parameters (attack, decay, release), the front panel knobs go from 0.1ms to 6s on the attack time (starting at 0V) and are quite comfortable to adjust. Using the CV inputs from the backplane, the time range can be extended a lot. Extremely long times can lead to accuracy problems due to leakage currents.

The design uses a very small timing capacitor (1nF) to get the quick attack times using a standard OTA, and exactly this capacitor is quite small for longer times. If you build the circuit, feel free to replace the capacitor by a larger one if you don't need the super-fast timing. The rest of the circuit doesn't need to change for this.

Tomorrow, demonstration video, photos and schematics will follow. The board layout will also be there, but this is just for completion. It might be very difficult to route this layout on a 2-layer PCB, but i needed to save space there because of the overall construction of the synth. I never take an enclosure and build the synth according to the size of the enclosure, this is unsuitable for my featuremania :)