23 December 2009

Yusynth (Part 16)

Today I finished two YuSynth LFO modules. Again I made everything myself on these modules including etching the PCB's and the front panel designs. I also had these front panels made by Schaeffer. And I used a bridechamber 2 pot bracket as you can see in the picture on the left. I had some more holes to drill on these brackets since the PCB has 6 fastening points in stead of the usual 4. I guess because it is a long PCB and you don't want it to short circuit on the pot bracket when it should bend. I keep having trouble to drill these holes exactly on the right spot. Just clumsiness I guess ;)

And here is a picture of the wiring I did. As you can see there are quite some wires on this PCB. 6 of them already go to the rate selection switch. Which is kind of a cool features because it increases the frequency span a lot. Of course I had the wires correctly the first time on the switch, but doubted that later on and after switching them I found that they had to go back again ;) Ah well this way you learn to test better. The reason I started to fiddled with the wires was actually because it didn't function when I was calibrating the first one.

The first thing I did after that was comparing the PCB's of both LFO modules. And after about 10 minutes of studying and measuring a bit, I found that I had two resistors wrong. On one PCB were two 2k7 resistors and on the other two 8K2 and there were supposed to be one 2K7 and one 8K2 on both of them. I had to remove the PCB's again from the pot brackets to desolder these resistors. Since this is a single layer PCB that is doable with just a desolder pump. I maned to do so even with saving the resistors and just switching from one PCB to the other.

And here are the two finished LFO modules. As you can see in the picture they have another neat feature called Sync. This makes it possible to synchronize two modules to each other of to for example to a sequencer clock or any other signal. Further it has an FM input making it possible to do frequency modulation on an external CV signal. I tested all the features and it works like expected. The only thing I see is a little dip just on the crossing point of the uppper and lower part of the Triangle and Sine wave. I'm not sure if this is normal, but I can't get it away using the trimmers anyway. Actually I don't think it is a big problem either. Well all in all a productive day and two new modules :) More to come soon. I'm on a roll now :) I'll let you know soon.


yusynth said...


The little glich at the summit of the triangle is normal, it is small and short enaough that normally you would not hear it when modulating a VCO for example.

Synth.nl said...

OK clear. Thanks Yves :) Merry Christmas!

Arduinome said...

I'm building a yuSynth VC-LFO, but can not find the Timers T2a, T2b, T1 and T3 (10 turn 10k, 47k 10 turn). Can you tell me where you purchase your electronics? I saw a picture of you that shopping at the "farnel" but already tried it and did not find.
You're a mega builder modular synthesizers:) great collection.
Where can I hear your compositions?

Nuno Correia

Synth.nl said...

Farnell is here:


My music is here: