SPST bypass

[lightningfingers]

Hey,

I need a bypass with some very strange requirements, it has to work from a normally open SPST, so the effect only works when the switch is closed, (so could it be some sort of inverter bypass?). Not tone-sucking would be nice but its not completely nescessary.

All participations are most appreciated :mrgreen:

[dolhop]

Can you describe the switch in a bit more detail?  Is it a momentary switch (not that it's relevent, just trying to get a feel for your application)?  Is it an SPST (three terminals, centre terminal connects to one side, then the other when switched)?

[lightningfingers]

Its an SPST switch, 2 contacts that connect when the switch is pushed, and break when it is released.

[dolhop]

So, you're pretty adamant about using this switch?  Sentimental value?    Some of the hardcore guys here would provide the best solution.  I'm thinking that you could use the switch to drive a couple of FETs as switches....so, at the output use a summing amplifier to add the wet and dry signals - each passed through FETs - one of them normally open, one normally closed - and use the switch to open/close each of them.

[niftydog]

use the switch to activate a DPDT relay.

or

tie an inverter input to 5V via a resistor and use the switch to short the resistor to ground. Thus, when the input is at 5V, the output is at 0V, and when the input is at 0V, the output is at 5V. Use this to drive a CMOS switch or FETs etc.

[dolhop]

I think a relay would be much to noisy.....

[Mike Burgundy]

a relay too noisy? Why? If the circuitry around it makes for a nice soft changeover (no bouncing contacts) it's real, real nice...

[David]

Hey,

I need a bypass with some very strange requirements, it has to work from a normally open SPST, so the effect only works when the switch is closed, (so could it be some sort of inverter bypass?). Not tone-sucking would be nice but its not completely nescessary.

All participations are most appreciated :mrgreen:

Read Andrew "The Tone God"'s article on Wicked Switches.  Look up the option for non-momentary switch used with inverters.  This documents how to build a true bypass electronic switch with LED indicator that is controlled by a SPST switch.  Works well on breadboard.  Looks like a bear to wire.  Also, be sure to read the article on electronic switching with the CD4053 on GEO.  These will tell you more than everything you need to know about electronic switching...  GUARANTEED!

[lightningfingers]

Thanks guys, I have it figured now, and my rocker pedal is done....now to do something crazy with it..........

[Gilles C]

That's Tonegod info

http://www.geocities.com/thetonegod/switches/switches.html

This week, I wired the version with FETs that is on Mark Hammer's site, and it works very well.

http://ampage.org/hammer/files/DUALLOOP.png

If you have the place for a small pcb, you could make yourself a version with the minimum you need. One FET for each contact that you want.

That's what I want do do, make a layout for a pcb that could be added inside any box, just like the Millenium Bypass.

But it won't be ready this week...

Anyway, people are not too crazy about FET switching. True Bypass is much more appreciated. So, maybe you should use a relay.    :wink:

Gilles