This thread is for the building and use of the 1181 Dual VCA. Info Here 
I’m really liking the artwork on this one!
haha thanks! this one took a rather long while to doodle out!!!
also I have just realised, the front panel is symmetrical so It can be put on either way!
4 Likes
welp, looks like I am using this Panel backwards. lol 
2 Likes
Here is a BOM for the 1181 Dual VCA. 
When I tested my Dual and Quad VCA, I seemed to get very little range. I was using this out of my sequencer so don’t know how many volts it’s putting out but it was the same on both my outputs which worked with the VCO…
I need to find time to get back to testing, but is there any known issues?
Rob
1 Like
rather try to use a signal from an Envelope to trigger a VCA
Edit :
1 Like
Well I dug this out again, thinking it was fixed. But it was behaving even worse.
I noticed the LED’s never worked. And whilst watching the builders stream was looking for any glimmer of information… Before he even got to it I spotted I had left of the 2n3904’s Looking at the schematic i’ts obvious why the LED were not working. But still I was getting eratic behaviour or silence.
Re-hit all the solder joints on the IC sockets and hey presto it’s at least working manualy…
Rob
2 Likes
I’m looking at the schematic for this and… uh?
[Incorrect circuit analysis deleted to avoid anyone else getting as confused as I was]
Another minor matter: the input CV is divided down by a factor of 4 by the voltage divider on the CV pin. But per the Kosmo spec a CV range -10V to +10V is okay, and potentially the voltage on the CV input could be -12V to +12V. If that happens the maximum range for the CV input to the 3360, -2V to +2.5V, is exceeded.
1 Like
II2 is a current summing input, there shouldn’t be any significant voltage there to truncate.
2 Likes
Right, I was more confused than usual. Thanks.
1 Like
Maybe that’s where the zener diode was meant to be?
4 Likes