Tonepad Small Stone / Pieditra with actual ca3094 vs ca3080

[Racase]

Would I need to modify the circuit if I were to include the original ca3094 vs the Tonepad layout calling for ca3080s ics?  I have bought some I think they're the cool audio...  Anyway, what modifications would be required?  I see there's many more transistors in the Tonepad layout.

Thanks

[idy]

the 3094 has a darlington pair buffer built in, the other chips need one added. Tone pad is laid out for the 3080s with added darlington transistors buffers. GGG has a layout for 3094s.

[Kevin Mitchell]

I've built the GGG version with CA3094. Worked fine.

This page is a gem for fine-tuning a small stone - particularly regarding the bypass volume drop.
https://generalguitargadgets.com/wp-content/uploads/smallvlp.txt

[Racase]

Could I just bridge each Darlington pair?  I already own the Tonepad PCB.

[idy]

It looks like you could. Carefully compare the two schematics. I would maybe try one stage at a time just to prove the concept before you get too deep.

[Kevin Mitchell]

Could I just bridge each Darlington pair?  I already own the Tonepad PCB.

Omit the transistor pairs Q3&Q4, Q5&Q6, Q7&Q8, Q9&Q10, Q13&Q14, as well as all of the 2K and 47K resistors.
Bridge the base (pad 2) of the first transistor to the emitter (pad 1) of the following.

That should do it.

[Racase]

Bridge base to emmiters instead of emitter to base as in the schematic?  For only those ommitted?

Here's what I have, I bridged all the 2k and 47k and all the pins of the transistors that we ommitted:

[Kevin Mitchell]

I'm not quite sure what you did there. But it's not right.

Inside of the CA3094 the 2K, 47K and transistor pairs are all included - so you should not populate their places on the board.

For the "bridging", the point is to bypass (or jump over) the transistor footprints to complete the signal routing. I suggest using the empty transistor pads rather than wiring from one component to another since it would look cleaner.

Use wire jumpers rather than solder blobs.

[Kevin Mitchell]

Red X means remove the resistor (10 resistors) Edit: technically you don't need to remove them since one lead is not connected to anything - so they're not doing anything but taking up space.

Blue lines are jumpers (5 jumpers)


Definitely clean up your solder work. Let us know how it goes.

[Racase]

Finished today.  My Piedrita pedal build Works great and I recommend it .  I tore three traces so I made some connections with resistor leads.  I'm going to experiment with different transistors too since I've got sockets.  Thank you everyone.

[Racase]

[Kevin Mitchell]

Nice, good job!
Edit:
Though in your photo it looks like you were off a pin on the Q9 jumper. Fixing that will recover the 4th phase stage.