Help with em theremin construction

That could be a problem... all mine were on perf board and basically follow the original EM/ew layout.

Do real (as in made by Moog/BB) EW have ground plane ontop the board?  Ive never seen one in person.       I assume that the PCB are double sided.

We actually planned on getting perfboards today just to see if there are any improvements. I'm starting to realize that there a lot of things I might have overlooked before making the PCB. Oh well, you live and you learn.

If you have a fully grounded "fill" on your board, then you will have big problems - The biggest problems will be the closer to the antenna one gets (as in, the inductor closest to the antenna is the most sensitive) but really, ground fill in the oscillator and Eq areas is not a good idea at all.. If you have sensitive tracks on the 'solder' side, and a ground plane above on the component side, you are needlessly adding capacitance.

I would suggest that you start by raising the inductors at least 10mm above the board - but you may want to go to 20mm.

- or remove the inductors from the board completely (I personally think that having the inductors close to the oscillator is a daft idea - they should be mounted as close to the antenna as possible, with a wire to the oscillator - the connection point at the oscillator is the least sensitive to capacitance - so run the wire from this rather than running a wire from the most sensitive point, ie the antenna!)

With the EW oscillator fortunately (for you) the tank capacitance is high - so if you remove the EQ inductors and construct them in perf board close to the antenna, you will probably be ok.

But please note - I am NOT an EM / EW expert!

You are absolutely right Fred, I don't know what I was think when I designed the pcb. I should have consulted the theremin gods on this site. We are going to move all the inductors to a perfboard and test with that. If that doesn't work we will unground the board and manually wire ground to points on the circuit that need it.

"I should have consulted the theremin gods on this site." - Antman

ROFLMAO ;-)

We have had trapped resistor spirits, capacitor and inductor spirits, active component spirits, metaphysical guidance..

there are undoubtably the spirits of the etherial sirens - and we now have an antique theremin shaman (with a peculiar bias towards high-end digital / FPGA circuitry)..

but to my knowledge, theremin gods have not yet shown themselves..

But then, as I am an athiest, perhaps they wouldnt show themselves to me.. ;-)

There are  definitely RF Demons.   try burning a candle.

Some RF demons.. UHF demons.. Microwave demons.. they are the ones to worry about - its the longwave demons theremin builders and players must support! - Particularly as so many were made homeless when long wave became unfashonable .. Theremins are one of their few sources of comfort.

You see, they chose me - More than anything else, they fear that theremins will go digital - that their comfortable few hundred kHz squat will fall victim to cold industrial might of the MHz processors.

I am their voice - an agent with background in the digital occult, but one who turned traitor on it, moving over to the slow side.

Yes, I joined Theremin World ! And I am now as mad as a hatter with a soldering iron!

;-)

"You see, they chose me - More than anything else, they fear that theremins will go digital - that their comfortable few hundred kHz squat will fall victim to cold industrial might of the MHz processors." -FredM

So would you be upset if I said the theremin I'm constructing will be converted to a digital device through an ADC converter we are also working on?

No - I wont be upset.

But THEY will be!

Hi all

I've been watching this thread with interest as I've taken a kind of shine to the EM theremin and was planning on making one if I had a few spare weeks.
Now my question is, that given the posts here by those with experience of building theremins (albeit maybe not the EM), seem to suggest relocating compontns, is the componet layout given in the original good or is there a better layout somewhere out there?

Thanks in advance.

Roy