True Bypass: Transmogrifox Relay Driver corrected

[Transmogrifox]

RG pointed out an issue with my circuit that needed to be corrected in this post:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=31968

I have set it straight so now everything is as it should be--no popping and all:

www.geocities.com/transmogrifox/relay

Oh, and the pins on the relay aren't labelled, so the schematic does not illustrate the polarity of the relay for correct LED indication as synchronized with switching.  It is easiest to wire however you feel like at first, and if the LED is on when the switch is off, then simply reverse the power supply reference on the input switch, resistor, LED section and reverse the direction of the LED and that would do it.

Otherwise, stand by as I have another hand-drawn diagram that shows the pin-outs and also markers for putting it into an BOSS SD-1.  I just need to scan it in and post it.

[R.G.]

One last thing: the capacitor and relay coil may give a big whop of current when the switch first makes. If that slug of current is traveling on the same wire as your input signal ground, you're going to hear it.

Wire this up with the switch wired to the capacitor with a single wire. Then take a second wire from the switch to the battery (-) terminal.  That lets the capacitor and switch make a nice, tight loop to supply the sudden current in the relay coil and keeps it out of the power supply wiring.

Even better is to put a 10uF to 22uF cap across the switch throws where they connect to the power supply. That ensures that any sudden pulses come from the new cap, not the battery, and therefore does not come through the power supply to the effect. Only a very slowed down version of the pulse comes to the new reservoir cap, an it's slow enough that it will be subaudible.

This is belt-and-suspenders stuff, of course. But some effects are high gain, hign input impedance, and low power supply rejection things, and may need it.

Having thought about it, you also need the resistor/LED from relay terminal to ground, not parallel to the coil. The cap in series with the coil would cut off the current to the LED, too. Applies to the hard switch version.

Trans, you want me to sketch this up?