12 January 2010

Yusynth (Part 21)

Today I finished another Yusynth module. This time it is a Voltage Controlled Oscillator or also called VCO. This VCO is quite versatile it has a Saw, Triangle, Sine and Pulse output. The Pulse output has Pulse Width Modulation and there is also a Sync input. Further more it has two V/Oct inputs to play melodies on it and it also has two Frequency Modulation inputs. One is Linear and the other is Exponential. Yves offers three versions of this VCO on his website. I build mine using SSM2210 Dual Matched NPN transistors.

In the picture on the right you see the finished module from the back. There are quite some wires on it, but as usual Yves has a very clear wiring schematic on his website. The only tricky thing on this PCB is that you have to put a tempco resistor on top of the SSM2210 (or whatever you chose). You can see it in the right top corner of the picture (if you click on it you get a larger version). I use special heat conducting pasta to make sure that the temperature is transferred as good as possible from the SSM2210 to the tempco.

After that I tested the module. As always first the magic smoke test. And after that I looked at the different output signals coming from the module. They all seemed to work. After that I tested all the inputs by putting a signal on them from the PC Function Generator. Everything seemed to work as expected. Next thing left to do is the calibration procedure for the wave shapers and after that the most important thing the tuning procedure to make sure it tracks 1V/Oct over a couple of octaves. I haven't done this before so that is new for me as well. I'll update you on the result.

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