Author Topic: Switching transistors  (Read 1464 times)

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dano12

Switching transistors
« on: January 06, 2009, 07:34:26 PM »
Here's a fun way to add switchable transistors to a circuit and use up loose parts sitting around the bench.



A 3PDT switch, a few rubber feet to add clearance, a strip socket and some epoxy.

Wired into the enclosure:






xshredx

Re: Switching transistors
« Reply #1 on: January 07, 2009, 03:01:13 AM »
Great idea...   I spend yesterday evening trying out a whole bunch of transistors (I'm making a replacement for a friends old russian big muff he doesn't want to gig with anymore because he wants to keep it in the clean state it is now).
And although we found a set of transistors that are really close in sound to the russian big muff, he also seemed to like the sound of high gain transistors... making Q2 and Q3 switchable like this would be a good idea...
thanks.

reverbie

Re: Switching transistors
« Reply #2 on: January 07, 2009, 03:39:36 AM »
Dano...

why not just break the strip sockets into single pieces and mount them directly into the switch lug holes?

just an idea.

My tender heart bleeds for you, idiot.

liddokun

Re: Switching transistors
« Reply #3 on: January 07, 2009, 05:58:11 AM »
Nice. I'm planning on doing this for an upcomin fuzzhead project so that I can have a Si/Ge transistor switch.
To those about to rock, we salute you.

dano12

Re: Switching transistors
« Reply #4 on: January 07, 2009, 07:21:02 AM »
Dano...

why not just break the strip sockets into single pieces and mount them directly into the switch lug holes?

just an idea.



nice idea! I wonder though if solder alone would provide enough strength while removing and inserting resistors...

might work!

oskar

Re: Switching transistors
« Reply #5 on: January 07, 2009, 07:29:05 AM »
Nice assembly. Your patience is what impress me the most. How big is your staff?   ;)
tip. Most of the time you'll only need to switch two legs so you can leave the last leg, like the emitter to ground for instance, hardwired together. So then you'll only need a dpdt.

earthtonesaudio

Re: Switching transistors
« Reply #6 on: January 07, 2009, 08:00:25 AM »
If you wanted to go ultra-mega-PWNED1-deluxe, you could have an adjustable bias pot in series with one of the transistor legs, so switching also toggles between two different bias values (for a more consistent comparison between different transistors, or to demonstrate different bias settings on the same kind of transistor).

frank_p

Re: Switching transistors
« Reply #7 on: January 07, 2009, 12:03:21 PM »
Yes, I took Alex's good idea for a Si-Ge rangemaster:
Thanks Alex it's working fine !



It's perhaps a little difficult to see but at the top-right of the picture you have all that is needed to make a switchable gain stage.
Everything is mounted on the 4pdt switch:

- The transistors and the Rc resistors that are needed to bias the transistors correctly are mounted to the exterior-side lugs of the switch
- The Rb1 and Rb2 resistors and the cap-collector are mounted to the inside lugs of the 4pdt.

So all the double-rangemaster circuit is mounted directly on the switch.

I biased the transistors on the breadboard and when the voltages were correct, I soldered everything on the switch (I didn't want that Gus say to me: sockets is not designing  ;D).


« Last Edit: January 07, 2009, 12:18:22 PM by frank_p »

reverbie

Re: Switching transistors
« Reply #8 on: January 08, 2009, 12:03:26 AM »
Dano...

it works with hard mounting them.... i did it today. i will try to figure out how to post a photo. The solder strength was absolutely no problem. maybe after a hundred tweeks they would loosen up, but everything seems good.

My tender heart bleeds for you, idiot.