Time to add a footswitch to my Dean Markley K-20X

[joecool85]

Interesting Juan, I had no idea.

Also, no worries about parts count, I'm actually increasing it by 2 by not using the drop voltage resistor but instead using a L7805 (and associated input and output caps) that I have lying around.  I'll put it all on a little daughter board and mount the L7805 to a heatsink and the heatsink will be mounted to the chassis.  The daughter board will be veroboard and have two standoffs plus the L7805/heatsink keeping it in place.

[J M Fahey]

Well, if you have 5V available and your relay coil is 5V, fine.

[joecool85]

Well, if you have 5V available and your relay coil is 5V, fine.

Yeah, I have the L7805 and heatsink from something I gutted a while ago (probably a computer PSU).  Hopefully I'll be doing this project in the next month or so.

[polo16mi]

Sorry about refloat this post so lately, but making kinda research about implementing a footswitch change channel for my amp.

I wondering if best to use relays for it, or digital IC, or something else?

What you think about it?

I guess that using relays will produces a "pop" noise when you make a change of channel. I right? or is easy to avoid it?

[Roly]

Tastefully chosen resistive dropper in series.  Catch diode is good, snubber is better.  Catch diode AND snubber is best.  The snubber is a resistor and capacitor in series, across the relay coil in parallel with the catch diode.

General rule of thumb, a resistor equal to the coil resistance and a cap in series from about 0.1uF for a low current relay coil up to 0.47uF for a heavy coil.  Snub the coil, no "pop".

The problem with just a diode is, particularly if there is any logic nearby, that the diode switch-on time is finite enough to flip flops and the like, and the snubber stops that little spike (been there, been done over by that; a spike a couple of uSecs wide by 3kV high; this is how car ignition systems work you know  8| ).  You don't need a zener for a relay supply. Just one more thing to fail.