photonic juergulator revisited

[blackieNYC]

GGBB's schematic has both ends of the perc pot grounded - isn't this the one with one open end?

[GGBB]

GGBB's schematic has both ends of the perc pot grounded - isn't this the one with one open end?

This is Mk2 - Jimi's changes are here: http://www.diystompboxes.com/smfforum/index.php?topic=109770.msg1004778#msg1004778.

[pinkjimiphoton]

thanks for the explanation, ron... 

but why does it work with two npn's?  i tried a bunch of npns and pnps in q1 after discovering my mistake,
and it didn't seem to matter much which was in there... as long as they were GE.  npn's around 100hfe or pnp's around 50 seem to work the same.
weird, WEIRD!!   

that kinda explains what the cap is doing... but why would it work temporarily with no q1 (if ya pull q1 while the circuit is powered, it will keep working and sound the same until the electro discharges... about a minute. pull q2 and it doesn' work at all)

[GGBB]

I've read much more knowledgeable people state that BJTs will work in reverse. So perhaps in a way, at least with respect to DC voltage, the NPN is in reverse but still functioning somewhat. That's about as much as I could think of to explain it.

[thehallofshields]

First off. Good job. However

I'm a little skeptical of your Perc control though.

All the way Left you've got:
0k in Series with 47K->Ground.

At Center Position you've got :
50k->Ground in Parallel with 97k->Ground giving you an equivalent of 33k. Add the 47k Series giving you 80k ->Ground

Then all the way Right is:
100k->Ground in Parallel with 47k to Ground giving you 31k. Add the 47k Series and you've got 78k->Ground.

Did you try a simple 47k -> 50k Pot ->Ground?

Why not just make it simple and use a 50k Pot-> Ground?

[GGBB]

I've been revisiting this circuit and noticed the links to my layout that I posted earlier got messed up somehow and my layouts aren't in Aron's gallery anymore. No worries as I've revised it anyway. Here's the new one below (still untested).

[pinkjimiphoton]

for posterity, this was the final version, verified. sounds/works great