Synthrotek Vac Pac - Add CV to anything kit

[kaeth]

http://store.synthrotek.com/Vac_Pak_Kit

Saw this and had to share. Let's you swap any pot or resistor with CV input. So many possibilities for modders, or anyone who doesn't already have a good knowledge of circuit design.

LFO's on everything! Give tremolo and vibrato pedals AM or FM capabilities with a small oscillator circuit.

[Bellyheart]

That's wonderful!

[eatyourguitar]

Caution: Do not exceed +10V DC on the CV input, more

there is no protection from killing your vactrol.

Set the Scale and Offset trim pots to dial in your optimal resistance, with a range between ~300 ohms to ~10M (all vactrols are a little different in range).

I have these exact vactrols in large quantity. it is a silonex NSL-32. I would not power the vactrol to go lower than 10k or even 5k. I don't want to blow it up. especially if I sell it and I don't want it to come back. advertising 300 Ohms to your customers is exactly why they say "may burn up your vactrol!" cause they designed it that way.

It does not teach you anything about electronics it just takes your money and does it for you. there is also the whole issue of getting a nice curve to the range of the vactrol so it does not just work like an on off switch. this can not be solved on this kit unless you reverse engineer it back to schematic but at that point you could just do a much simpler custom version with 2 resistors and no opamp. however you could only skip the opamp if you had access to the pedal sending CV to look at it and possibly mod the output impedance. or at the very least, you build it to match one pedal and always use it with that pedal. you do not need to open it up in that case.

I got these when they were 10 for $2. this is the part that is used in the synthrotek. if anyone wants me to draw the schematic I would gladly do it and post a tutorial.
http://www.goldmine-elec-products.com/p ... er=G15396B