04 November 2009

Yusynth (Part 11)

Today I worked some more on my YuSynth project again. I started finishing up an ARP4072 clone VCF famous from the ARP2600. Yves provides three options to build it either based on 2SA798, 2N3906 or more common BC557 transistors that need to be hand matched. I described earlier how I wrote the measured values down on a big piece of paper. Well in the picture you can see this. Most modern multimeters have a possibility to measure the HFE factor of transistors. And just put the transistor is and read out the value. I barely could make the necessary 6 matched pairs. But I managed.

After that I soldered the transistors to the PCB and started on the wiring. Again it was quite similar to the other two Yusynth filter modules I build. It is nice that Yves keeps the same logic in all his designs. Saves a lot of puzzle time :) You can see an empty IC sockeet on the PCB. There was supposed to be a LM3900, but it seems like I forgot to order it before, or just couldn't find it. This morning I tried to order one, but the minimum order value was 25. Well they are very cheap so I did it anyway. So I have 24 spares now. Ah well I'm sure I'll need some in the future.

Here is a picture of the finished module. I could test it of course because the LM3900 is missing. Same goes for calibrating. You can see this one has a 1V/Oct input as well. I can't wait to actually play a melody on a self oscillating filter actually. But first I want to finish up building the modules. I have quite a pile of stuff lying around for over a year that I really need to finish, if only it was to clean up the piles and to make sure I don't lose track of everything. Or even worse lose parts. What frustrated me though is that Bridechamber didn't have front panels for the Yusynth VCO. I really would like to build some Oscillators to make some music on them. So I started looking for another solution. But I couldn't find anyone who makes them. But I did find Schaeffer AG in Germany.

Schaeffer is a company that makes front panels from aluminum. They have a nice piece of software on their website that you can download and install. From that software you can design you own front panels and even order them online directly. So I designed my first front panel in MOTM style and ordered it. It will take about two weeks before it arrives and I'm very curious how it will turn out. It isn't cheap by the way. But the letters are engraved and painted to I'm sure it will look very professional when I didn't screw up ;) I'll let you know when it arrives. If this works I will make more for sure.


yusynth said...

Hi Michel

Great to see that you're progressing with this project.

yusynth said...

By the way let me know when you'll be working on the yusynth VCO because there is a mod to improve the SYNC mode. Has it is now it operates in soft sync mode that is the slave VCO will lock on the frequency or on the harmonics of the master VCO. In order to have hard sync , it is just a metter of adding a switch connected in parallel with the input capacitor of the SYNC circuit.

Synth.nl said...

Hi Yves, thanks for your comment. I plan to build VCO quite soon actually. Is this mod on your website?

yusynth said...

Not yet but it wil by the end of this week-end ;-)

Synth.nl said...

Ah. I won't finish them before that :) Thanks Yves!