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DIY Stompboxes => Building your own stompbox => Topic started by: Austin73 on May 13, 2006, 01:49:52 PM

Title: footswitching transistors
Post by: Austin73 on May 13, 2006, 01:49:52 PM
Probably a really stupid question that has been answered a thousand times but anybody got ideas on using footswitch to toggle between two transistors ie low and high gain. I sort of get the idea with a 3PDT Swicth but would like LED indicators if poss dont want to go down the 4PDT but maybe millenium bypass indicators?

Cheers

Aus
Title: Re: footswitching transistors
Post by: petemoore on May 13, 2006, 02:16:45 PM

[/quote]ideas on using footswitch to toggle between two transistors ie low and high gain.
  >There are a number of ways that come under this generally..to be specific:
  >You mean switching between HG and LG transistors in the same circuit position, or
  >Switching the gain of a transistor in circuit?
  >Figuring out either/both can be done/
  I sort of get the idea with a 3PDT Swicth but would like LED indicators if poss dont want to go down the 4PDT but maybe millenium bypass indicators?
  > after Deciding what connections you need switched, an appropriate switch type can be chosen.   
Title: Re: footswitching transistors
Post by: R.G. on May 13, 2006, 10:54:57 PM
With silicon transistors, you can parallel the collectors and emitters, and switch the bases. The open base transistor(s) will be effectively open circuits, and only the base-driven transistor will be active. Other switch sections can drive LED, etc.
Title: Re: footswitching transistors
Post by: Austin73 on May 14, 2006, 06:02:20 AM
Cheers R.G, Thats just what I wanted to hear. Will that work with a npn and a darlington fancy switching between 2n3904 and Mpsa13 in a Buzz Box type pedal

Aus
Title: Re: footswitching transistors
Post by: Austin73 on May 14, 2006, 09:47:48 AM
Using ROG's Buzz Box layout and Bancika software badly I have quickly drawn this up as an example. If you look at the 2 transistors on the left  (2N3904  and MPSA13) if I wire between the cuts on the Base track would that work? (Yes I know the end cap is the wrong way round but can't do multiple undo's with the software!)

Aus

ROG Layout
http://www.home-wrecker.com/bazz.html (http://www.home-wrecker.com/bazz.html)

My crappy layout!

(http://www.snapfish.co.uk/slideshow/AlbumID=42416300/PictureID=1246393144/a=29987928_29987928/t_=29987928)
Title: Re: footswitching transistors
Post by: Austin73 on May 14, 2006, 09:48:22 AM
(http://www.snapfish.co.uk/slideshow/AlbumID=42416300/PictureID=1246393144/a=29987928_29987928/t_=29987928)
Title: Re: footswitching transistors
Post by: Austin73 on May 14, 2006, 09:49:16 AM
(http://www.snapfish.co.uk/slideshow/AlbumID=42416300/PictureID=1246393144/a=29987928_29987928/t_=29987928)

http://www.snapfish.co.uk/slideshow/AlbumID=42416300/PictureID=1246393144/a=29987928_29987928/t_=29987928 (http://www.snapfish.co.uk/slideshow/AlbumID=42416300/PictureID=1246393144/a=29987928_29987928/t_=29987928)

Title: Re: footswitching transistors
Post by: Noplasticrobots on May 15, 2006, 04:22:20 PM
R.G. your answer is so obvious it's making my head hurt. Why didn't I think of that?!??!