Univox Unidrive

[nemo]

I'd like to attempt to build a Univox Unidrive.

I've never built a pedal before but i've soldered countless cables and would rather learn to read a schem that pay $600 for one of these.

http://www.univox.org/pics/schematics/unidrive.gif

These are in a volume pedal type housing. Are these easy to come by? Where can I get one?

http://www.univox.org/pics/catalogs/unidrive_catalog.jpg

Does anyone know what trannies these originally came from?

Any help would be greatly appreciated.

Thank.

[smoguzbenjamin]

That tiny circuit costs $600! :shock: Wow.

Go out and buy a second hand volume pedal, and if you want to build this, just throw out the innards or better yet keep them and use the for something else You could also get a broken wah/expression pedal, whatever suits best. The schematic says you need 3 2SC859 transistors, but I doubt you will be able to get those... Plus I recommend you use 16v caps and not 10v It won't blow so fast that way.

[nemo]

$600 is an estimate in Canadian dollars BTW.

I've seen less rare pedals for around that here.

I'm not familiar with 2SC859 transistors, but then i'm not familiar with any tranny that wasn't in a fuzz of some sort. Who makes the good ones?

As for caps, my knowledge is relegated to guitar tone caps. Are there any favored types i.e. Paper-in-oil, ceramic, etc...?

[petemoore]

A stacked resistor network [increased resistance in the signal path as the further you step down] on the input, as a pregain control.
 Doesn't the guitar volume to the same thing? Seems like a big pot...[add up the resistors and find a pot about that size] would do the trick 'better'...I guess if your guitar has no V control...
 Then theres a Fanci Fuzz Face...now that part looks more interesting....what's just past the FF part.
 I would breadboard that, you can always vary resistance like they have at the input somehow...I'm trying to figure out what they were thinking there with all those R's and the fancy switch...actually it would probably give a nice stepped gain control....lotta trouble when the same basic thing is the guitar volumes.
 I didn't scope closely at the tail end part past seeing it's an emitter follower, good for running cable length or wah, and that there are some extra caps probably for tailoring the frequency output.
 Looks kinda old, I would trimpot Q2 [man I type that alot] and try some BCxxx's or Ge transistors in it. Ge's would be easier with a matched pair for Q1/Q2....possibly mod/stick a low gain Si Q1 and  a Mosfet for Q2...checkout Runoff Groove's FF articles...then compare that to the FF in this circuit.

[nemo]

Thanks for the tips. I'd imagine the BC whatever transistors would be better suited as they're silicon (I believe).

Sorry if i'm in the dark about the Q1/Q2 talk. I'm pretty ignorant at the moment.

I've got a friend with an old Morley Wah/Distortion he never uses. Its got some external knobs already. I'm going to check it out to see how suited it is for this kinda thing.

Maybe I can scavenge a few parts.