quad Transistor switch

[Christoba]

I'm having a heck of a time figuring this out so please forgive the ignorance.  I'd like to use a single switch to swap 2 Ge PNP transistors in a FF with 2 Si PNP transistors.  I thought that I had it figured out using a 4PDT switch.  However, I realized that I did this based on NPN transistors and now I am second guessing the whole thing.  Surely someone has done this before (already searched and couldn't find it).  How would you do this in the cleanest way possible?

Thanks,
Chris

[TejfolvonDanone]

Isn't it a whole lot easier to build 2 FFs and switch between them?

You need to leave one of the trannies legs constantly in the circuit. Eg you don't switch the emitters of the trannies. Then you connect the first PNP's collector to the upper side of the switch and the second to the lower side. Where the collector should go in the circuit goes to the middle lung. You do the same of the base and the second transistor.

[digi2t]

How about a blend pot instead? See the Gemini III Fuzz schematic. Then you can have one, or the other, or both to varying degrees. Lots more tonz in da box.

[Christoba]

Funny enough, I thought about that but couldn't come up with a way to integrate it into the circuit.

[Christoba]

This was what I had come up with previously with the difference being the NPN transistors and leaving the base connected to the circuit while switching the collectors and emitters. I'm trying to think of a clean way to do this with sockets.  I suppose I could vero board little daughter boards for each transistor set.  Anyone have a sexy way to do this?

Isn't it a whole lot easier to build 2 FFs and switch between them?

You need to leave one of the trannies legs constantly in the circuit. Eg you don't switch the emitters of the trannies. Then you connect the first PNP's collector to the upper side of the switch and the second to the lower side. Where the collector should go in the circuit goes to the middle lung. You do the same of the base and the second transistor.

[PRR]

> based on NPN transistors and now I am second guessing

If they are all the same type, why does the switch care which type they are?

[Christoba]

Pnp versus NPN would change how I mount them to the circuit and the switch.

> based on NPN transistors and now I am second guessing

If they are all the same type, why does the switch care which type they are?

[snarblinge]

I went with two switches, that way you can have Si/Si Si/ge ge/ge or ge/Si external bias made it useable.

Dpdts are cheaper than the 4pdts I could get

[antonis]

Dpdts are cheaper than the 4pdts I could get

FF remaining components are much chaper than any combination of xPDT switches..

[Christoba]

Alright.  I got it running and it works like a charm.  I added a bias pot to the front so that I could tweak when going between transistor combos.  I used triplets of sockets directly soldered to the 4PDT toggle switch so I could swap out for different combos.  Currently I have 2N3904s and AC128s.  I shoehorned a rangemaster (added the range selector pot) and fuzz face (lots o' pots on this one, see the yellow knobs) into a 1590BB.  Ill add an order swapper toggle once the toggle comes in.