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DIY Stompboxes => Building your own stompbox => Topic started by: jimbob on June 16, 2008, 09:51:58 PM

Title: spdt on-off-on - choosing between 2 resistors but the middle position is off
Post by: jimbob on June 16, 2008, 09:51:58 PM
I have a spdt switch i wired to switch between 2 different resistors with the middle for common. The problem is I didnt realize this was the on- on- on as the others so when I switch between the 2 choices theres 3 positions.

What can I do with this and still keep the 2 choices without the dead middle. O r is there something else I can do with the middle? Does it have to be off?
Title: Re: spdt on-off-on - choosing between 2 resistors but the middle position is off
Post by: GibsonGM on June 17, 2008, 12:18:56 AM
You could jump one side to the middle and it would be "on-on-and the same on as the middle" (SPST), I guess....
Title: Re: spdt on-off-on - choosing between 2 resistors but the middle position is off
Post by: MarcoMike on June 17, 2008, 05:39:19 AM
mh... not really sure about that solution... you would have the selection bertween R1 and R1parallelR2

Instead there are many wiring options that result in a 3 resistors selection:

    °--------res1---|
°   °                    |
|   °--------res2---|---a
|            |
|---res3--
|------------------------b

this is one of those... options are: R1p(R2sR3), (R3sR2), R2 

s:series, p:parallel