Question for R.G. regarding Transmogrifox latch relay switch

[Incubus]

You mentioned in your description of the cct at this link:

http://www.geocities.com/transmogrifox/relay

That if it's to be used with a SPDT switch, the inverter can be omitted, and that the LED/resistor can be placed in parallel with the coil.

So then, if I do it this way, (as I'm going to try it in my Vox V847 Wah), now that the inverter is gone, will I still need a diode in parallel with the coil for protection ?

One more thing, the 4.7M resistor at the input socket, is this to reduce pops ?

Does the inclusion of this resistor depend on the input section of the effect it's used with, as some effects (ie MXR Microamp from Tonepad) have a large value resistor on the input to ground already (22M if I remember) ?

Last question, is the 100k resistor from output to ground, always required or does it also depend on which effect you use it with ?

Thanks for posting your circuit description and thanks Transmogrfox for the circuit.

[R.G.]

... if it's to be used with a SPDT switch, the inverter can be omitted, and that the LED/resistor can be placed in parallel with the coil.

So then, if I do it this way, (as I'm going to try it in my Vox V847 Wah), now that the inverter is gone, will I still need a diode in parallel with the coil for protection ?

Probably not. The capacitor is effectively in parallel with the coil, and should suppress any transients.

One more thing, the 4.7M resistor at the input socket, is this to reduce pops ?

Probably. I hate to see that 100K on the output though. Loads the guitar when the effect is bypassed. That should be 1M or more.

[Transmogrifox]

Yeah, the positioning of that 100k, and even the 4.7M were hodge-podge additions.  I should modify it and do it right.  That 4.7M is supposed to be connected to the "Send to FX" lug of the relay, and the 100k resistor should be connected to the "Return From FX" relay lug.

RG is absolutely right, that 100k resistor does load the guitar.  Even the 4.7M is not good if repeated for multiple FX using that kind of bypass scheme.  

The 4.7 M and 100k resistors are meant to reduce switch popping, but are not in the correct locations in that circuit (sorry to all you poor people who build from these schematics and have to trust the designer).  The output pot of a guitar (usually 500k) does the trick of referencing all the contacts to ground when in bypass mode.  It's the FX inputs and outputs that should be referenced to ground so that both are at the same potential when the switch is engaged.

Thanks for pointing that out, RG.  Unless the effect that was being sent to and returned from had pull down resistors on the input and output, the stuff I added in that circuit isn't doing anything to reduce switch pop anyway!!!  Doh!