Post your Silicon Chip/Jaycar kit questions here!

i got it tuned to a nice playable range but there is one other thing. it seems as though the volume circuit is not working correctly. the volume knob does nothing and the volume antennae doesnt do anything unless i physicaly touch it which mutes it. and while i was trying to tune the volume circuit i noticed that i could achieve two other undesired effects from the volume knob and rod.
A) with certain settings of the volume oscillators the volume knob kills the pitch if i turn it down a little, and the only way to get it back is to reset the theremin. and the volume antennae does the same when i get about three inches away from it.
B) if i tune the theremin to where there is no pitch then the volume knob and antennae control the pitch but the signal is very low

any help greatly appreciated

From your description, the volume circuitry may be weakly heterodyning with the pitch circuitry.

When you adjust the volume coil, you may notice two "peaks" in volume: one that is weak and one that is strong. You want to tune to the strong peak.

Perhaps someone who has built a Jaycar can give you more specific instructions.

I would suggest that you have the Theremin working properly before you start making mods. That way, if a mod doesn't work, you have a baseline to which you can fall back.

Pleased to hear that you are past the power supply issue. Let the fun begin! :)

I'm interested in the idea of getting it working correctly before making mods: I was thinking about making the mods from the "Maxie's mods" page here, but I was planning to build them into the instrument from the start, on the theory that building it, soldering in the parts, then un-soldering it and redoing bits of it is just stressful to the parts.

(Still haven't started despite having had the kits for a month or more, I'll probably actually start in december or so.)

i have gotten the volume working now. i just didnt realize how small the volume control range was (only about an inch from full volume to mute and that inch is located several inches away from the antennae)or how sharp T4 was. i guess the first mods i'll do are to widen the range of the volume contol

ok, so i had it tuned and working pretty well last night i had even started working on greensleeves. then this morning i turned in on and it wasnt tuned as it was last night. no problem, i thought, it just needs to warm up. so i go and make a stand for it out of some scrap wood. when i come back 10 minutes later i have a new problem. the audio level is extremely low and the volume antennae is acting like like a pitch antennae again. no amount of tuning seems to do any good and when i adjust T3 it sounds like im adjusting T2. when i checked the circuit board i noticed that if i touch the + side of the the audio out the volume level comes back. im begining to think that its true that a theremin has more reasons to not work than one would think.

hi all, i'm kind of a newbie round here so maybe i'm not posting in the right place, what i'm looking to do is combine both s/c theremins, (i.e. the midi theremin and the analogue one). what i want to do is have a switch that changes the output from regular audio to the midi output, i can make new pcb's for the theremin no problem, so bascally i'm looking for a common point or someway to combine the two circuits into one. can anyone see a problem with doing this?

obviuosly i'm going to design a new box and get better antennae and the like, but if anyone could steer me in the right direction on this i'd appreciate it!

Gavsteed, I hate to burst your bubble, but the SC MIDI Theremin doesn't in fact generate any sound. It just generates MIDI output data. To combine the two SC theremins into one unit, you'd not only have to build in both theremins, but an entire MIDI synthesizer as well.

um yeah i know how midi works, sorry if i was unclear on that, basically what i wanted to do was combine both circuits onto one pcb and fit it in a custom box, with a midi port and a 1/4" output jack or whatever output for ordinary sound, and to be able to choose which output to use if ya get what i'm saying?

edit- also there are plenty of software synth's out there for midi products

Okay. So, let me try to rephrase my understanding of what you're saying: You want to build both of the Jaycar Theremin models into one unit and make them somehow selectable, for convenience or coolness or because you want to emulate the concept of the Ethervox without the Moog price tag. Do I get it? Now, please forgive me while I think aloud at you about this.

The Jaycar MIDI Theremin is two boards already, both reasonably dense looking (I've got the assembly manual open in front of me right now). The original model Silicon Chip Theremin kit from Jaycar is one board, if you're contemplating building the new Silicon Chip Theremin Mark II kit, I don't know yet how many boards it has. Honestly, I don't see a lot of reason to put it all onto one board - and in the case of the MIDI, one board is for the controls, allowing you to put the controls in one location (mounted just inside the top of the case) and the main circuitry slightly separate. So, there might even be some benefit to keeping the boards separate at least somewhat.

Next comes the issue of how they could be hooked up. I strongly suspect that if you set it up so that both conventional and MIDI theremin circuits are powered up at the same time, one would interfere with the other. Theremins are notoriously finicky beasts, and having another electronic circuit in the case with one could very well screw it up badly. So, I'd strongly recommend that a first step would be a switch to select which unit would actually be powered on. Some factors to keep in mind about this are that if they don't use the same power supply (I haven't checked) you'd have to have separate power inputs for each unit (so, two power cords to the case), and also that I understand the conventional Jaycar theremin takes some 10-15 minutes to warm up and stabilize, so you couldn't switch quickly back and forth between the two.

You may be able to prove me wrong. Perhaps both units can operate together in the same cabinet and not interfere. I sincerely doubt it, but if you can prove me wrong (by doing it) that'd be really cool.

Next is the antennas. I strongly suspect that if you wired both instruments up to the same antennas within the same case at the same time, the presence of the inoperative instrument will interfere with the operative instrument. So, I would suggest installing switches to allow you to select which instrument is connected. (Maybe you can find a way to use one switch that could allow you to switch the power and both antennas between the two units all at the same time? I think somebody must make triple circuit switches, don't they?)

Let us know how this project goes, it sounds like you could end up with a very unique instrument. If you make it work, please consider making detailed notes and detailed photos and submitting everything to Theremin World for our kindly webmaster to post it as an article, so others can try the same trick.

Finnicky and beast are both understatements of this this torture device. by the way my new set of problems ended up being the result a short in my guitar cord (im not sure how this could make the oscillators behave so oddly but then again it is a theremin). of course when i figured this out i ended up haveing to retune it again and i am again having the old difficulties with the volume antennae in that i cant get it to work past muting the signal when i physicaly touch it. and this tempermental bastard of a theremin kit seems to need retuning everytime i turn it on after a couple hours of it being off. however this is usually only a fine tuning that is required so im sure once i put in maxies finetuning panelmount pot that problem will be solved.