Page 1 of 1

question - rotary switch for transistor selection

Posted: Fri Aug 05, 2011 2:17 pm
by AC128
hey,

another totally noob question:

in beavis Big Steamin' Pile o' Mods V2, he uses a DPDT switch to switch between two transistors.
can the same principle be used with a rotary switch?
and which one? 2P6T? http://www.musikding.de/index.php/cat/c ... tches.html

uh, and how exactly would the transistors have to be wired? :picard:

I tried to figure it out myself, but it made me :animal:

thank you! :)

Re: question - rotary switch for transistor selection

Posted: Fri Aug 05, 2011 2:30 pm
by eatyourguitar
best way is to wire the 6 bases and 6 collectors to the separate poles of the switch so it breaks the connection when the transistor is not in use. all the emitters can be tied together on board. one half of the transistor is like a diode. it needs at least the forward voltage across BE or it wont do anything. also, C must be more posative (npn) or negative (pnp) than the base. with B no-connection and C no-connection, you'll never have anything going through the transistor.

Re: question - rotary switch for transistor selection

Posted: Sat Aug 06, 2011 1:26 am
by McSpunckle
If they're all biased the same way, you could really just tie one leg together. Doesn't matter which. With only one touching the board, the transistor won't do anything.

How much space do you have? You can get 3 pole rotaries, then it's pretty easy, but you may need to use a perfboard run a LOT of wires to the switch, or make a custom PCB.

Re: question - rotary switch for transistor selection

Posted: Sat Aug 06, 2011 6:15 am
by AC128
thanks guys.

space is nor really an issue, I'll get a 187x118mm if necessary.