spst remote switching without relay?

Started by shawsofhell, November 24, 2005, 01:10:34 AM

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shawsofhell

I am currently working on a micro controlled pedal switcher and one of my pedals has a control pedal input on it that allows you to change patches(5 in total) remotely. I want to build a simple switch that can turn on/off very quickly(~100ms) that will simply connect the two contacts. (Hope that makes sense) I don't want to use a relay because (a) i don't believe it will have quick enough switching and (b) since most have only a life of around 10,000 uses i dont think it will last very long in the circuit. I know that I could probably build this with a couple of resistors and and tranny but and help would be appreciated.

The Tone God

Various transistors could work. Probably some kind of FET like a MOSFET or JFET. You could use a logic IC like a 4066 or 4053. Even a opto could work. One of those should work dependong on the signal needs.

Andrew

jrem

what goes between the contacts?  5vdc?  analog?

A 4066 would probably do it unless its 110 or something rediculous . . .  they're cheap and easy to use.

Transmogrifox

Most SPST applications have a pull-up resistor at the gate of some logic device, and the SPST momentary just connects the gate to ground, giving a logic low signal. 

You may be able to connect one of the outputs of the uC directly to one of the SPST inputs.  PIC allows you to put their outputs into HiZ mode (and many other uC's are equipped with tri-state outputs), so you could switch between HiZ and logic low (or high, depending on the pedal's input--you just need to measure the voltages to find out).

With that configuration (as opposed to logic high/ logic low), you wouldn't even have to desolder and remove the switch.  You could still use the SPST if for some reason in the future you wanted to sell the pedal, or changed your rig in a way that put the pedal back on the floor...or just a plain emergency where your uC switcher gets beer spilled on it during a gig and lets out the magic smoke.
trans·mog·ri·fy
tr.v. trans·mog·ri·fied, trans·mog·ri·fy·ing, trans·mog·ri·fies To change into a different shape or form, especially one that is fantastic or bizarre.