Here are instructions to do some basic hacks to the theremin kit that you can buy from Make. True, there are already directions to do both of these things in the accompanying magazine, but what sets this how-to apart is that it is in English. If like me you can't read Japanese and unlike me, you couldn't figure out what to do from the pictures alone, this should help.
Basically, what I am doing is adding an audio out jack and also a bigger, sturdier telescoping antenna. This is a great improvement on the original.
Step 1: Go Get Stuff
You will need:
Gakken Theremin Kit (from Make)
A power drill
A mini screwdriver set
A mono jack with switch
Something with a telescoping antenna
A solder setup
Some extra wire
Step 2: Make the Kit
Before you can hack the kit, make it! See if it works. See how it works. Determine if you really want to make it better.
Alright, let's now assume that you do.
Step 3: Open It Back Up
Alright, lets make this thing better!
First thing is first, we need to open that theremin back up.
Remove the screw in the bottom and take the casing apart.
Step 4: Drill and Install
Drill a 1/4" hole in the back of the theremin just to the right of the speaker. This will be for mounting your audio out jack. I found holding the panel in place where it should be helped me to drill it on target. You should not do this. Always clamp things down and be safe when working with power tools.
Once you have your hole drilled, mount and fasten the jack in place.
Step 5: Wire It Up
Now is time to wire up the jack. This may require adding in a little extra wire.
First wire SP- (the wire on the right) to both the audio signal tab on the jack and the minus tab on the speaker (where it was just connected). Or, to put another way, wire the audio signal tab on the jack to SP- and the minus tab on the speaker.
Then wire the SP+ wire (the wire on the left) to the tab that connects to the big rounded metal bit on the back of the jack. Wire the + terminal on the speaker to the only other free jack (the tab that connects to the the little metal switch on the inside of the jack). This will turn off the speaker (break the connection) when someone plugs in an audio cable.
Step 6: Get a New Antenna
Take your "something with a telescoping antenna" and remove the telescoping antenna.
If it does not have a wire and piece of hardware on the end that will clamp nicely under a screw, you may want to attach one.
Step 7: Attach the Antenna to the Case
Insert the antenna into the case and secure it in place.
I drilled a small hole in the side and held it in place with a spacer and a machine screw.
Step 8: Wire the Antenna
Detach the old antenna by removing the screw and clamp in the new antenna in its place.
Step 9: Close the Case
Hot glue any exposed wires in place so that they won't touch anything and short out (and/or insulate them).
Also, chop off any part of the plastic inside the case that may interfere with it closing.
Once you have done all of this, close the case back up and reassemble it by inserting the single screw back into the bottom, putting in some batteries and closing it back up.