I need a little advice on a modification...

[Morbotron]

Hi there,
I'm a complete idiot and I dropped out of my electronics class in tech school. With that being said, I decided I wanted to install an optical theremin in a 1980's Lawsuit, Japanese Les Paul copy. The holes have been drilled. The hardware and 9 volt battery fits perfectly inside the volume/tone knob cavity. Ideally, I wanted to be able to solder the output wires on the theremin directly to the 1/4 in. output jack. I ASSUMED that this would allow me to play guitar and use the toggle switch for the theremin to switch back and forth easily. I was hoping this would work because I obviously didn't want to drill a second 1/4 in hole and install a second jack just for the theremin. After soldering everything, I plugged in and discovered my guitar wasn't coming through, although the theremin was working fine. So, I removed the theremin and the guitar went back to normal.
This is simple electronics knowledge that I should understand, but I sadly don't. Is there any way to avoid installing a second jack for the theremin and run it through the original guitar jack? I'm hoping there is. Thanks in advance for any advice.

[Jazz P Bass]

Can you post the schematic of your build?

[Morbotron]

I'm looking all over for schematics for this particular guitar. It's a Lotus brand Les Paul copy and from all I see, it appears to have the same wiring schematics as a regular Les Paul.

[Jazz P Bass]

Uhmm, I was hoping for the optical theremin schematic.

So, we will work without it.

Basically you want to use a SPDT switch.
The common terminal will go to the output jack.
One of the switched terminals will go to the guitar circuit and the other will go to the optical theremin circuit output.

[Morbotron]

You've solved my problem. This is something I should have thought of, but I was having a brain melt kind of day. Thank you very much!

[oc disorder]

Morbotron you wouldn't be the first or last to drop out of tech school...
anyway to save drilling another hole you could swap one of the tone pots for a switched one
like this
Alpha 500K Linear Pot w/ Push-Pull Switch
Also if the theremin is one that has enough grunt to drive a speaker the output would be humungous
going into a high impedance guitar input.

It would be best to terminate it with a resistor like 10 ohms or thereabouts (instead of the speaker) and feed the hot output
from that (not ground) via a maybe 10k resistor to the switch.

If the levels are too different (i.e. guitar compared with theremin output) perhaps try a , say 100k trimpot
instead of a 10k and adjust it till you get a satisfactory level !

Then of course wire in a strobe and chaser so the guitar appears to explode while you use the theremin
for added effect... people always seem to remember that rather than quality musicianship these days.....