lørdag 23. august 2014

The new super-mini-dual-VCA

I had a little time to tinker with Eagle again yesterday, and the result is a 40% smaller dual VCA. I've now put parts on both sides. I had to remove the separate CV input and trimmer outputs - instead of the trimmers you can put four 510 Ohm resistors on the board. The physical size (excluding pins) is now 27.3 * 16.8 mm.

I must admin that I like the original a little better as it had labeled pins and a nice big Xonik logo on it, but this one is very cool for being so small.

torsdag 21. august 2014

VCA works as expected

I tested the dual VCA today. Except for a mixup of output pin 1 and 2, it works as expected. At 10V the amplification is just slightly higher than 1. The VCA is linear, so at 5V it looks roughly like 50% amplification

VCA hooked up to the bread board. The two 1k trim pots are for adjusting the symmetry around 0V. 

Response at CV=10V. The outermost triangle wave is the output, and it's slightly larger than the input.

Response at CV=5V, the output is about half the size of the input.

torsdag 14. august 2014

7 saw controller board populated

I finished populating the 7 saw controller board tonight. It has not been tested yet but it looks good :-D

I didn't have any 22k 0204-size resistors, and I can't find any 3M3 or 4M7 resistors anywhere in that form factor, so I used normal 1% metal film ones instead. It looks a bit wonky but will work fine.

I have yet to test both the dual VCA and this board so not sure it works yet...

7 saw controller board

tiny LM13700 based dual VCA

Silk screen looks great :-)