[sdiy] question: a simple blend circuit?

[Shokwave]

----- Original Message ----- 
From: "Daniel Englbert" <denglerthm at hotmail.com>

> hi, i'm a relative fool when it comes to diy stuff, building guitar pedals
> from diagrams and kits is all my experience..

Join the club!

> is this hard to do? do i need opamps and a little perfboard? i have no
idea
> how to do this, if anyone could help or point me to some schematic (or
> better yet component wiring diagram) i'd be SUPER happy!!!

Well, it sounds like you are happy with the signal from the piezos as
is...if it doesn't require any amplifying/buffering, just try a pot in
there. It might be that no other circuitry is required.

If you need to boost the piezos a little, or just buffer them, a
non-inverting opamp circuit might be used...I bet one of the clever gents
here could tell us if it's possible to do "phantom powered" (I think this
only works with XLR connections to powered mixers, but I thought I saw an
"unpowered" guitar buffer somewhere...), or if you need to stick a battery
in under the pickguard. A 9volt will last forever in a circuit like that.
The basic design of a non-inverting amp is at
http://www.ecircuitcenter.com/Circuits/opnon/opnon.htm
You probably need non-inverting, because you want to blend it with the
pickup signal, so the phase needs to be the same. Er...that is, if the
devices both have the same phase to begin with; I am getting out of my depth
here. If mixing them deadens the audio, you could try an inverting amp
circuit :)

Check out: http://www.muzique.com/lab/buffers.htm , there's an opamp circuit
part way down the page that might be useful if all you need is a buffer
(unity gain), and a nice overview of various transistor circuits for the
same purpose.  I *know* there are websites dedicated to this kind of thing,
maybe someone has some pointers.

> i could barter some litttle bits of gear for the help! guitar pedals or
> something like that

I'm sure that isn't necessary, someone will help ya out enough to get that
working. Someone who knows more than I do, I bet.

-Darren