"Build the EM Theremin" - altered component placement - comments?

Posted: 10/11/2014 2:41:47 PM

From: Brooklyn,NY

Joined: 12/1/2009

For the mic flange-  check at large photography retailers or places that have lots of dj or production equipment.   Music stores never have them, at least from my experience. here in NYc, we have B &H  a photography superstore  that has everything from cameras to phantom quadcopters.   Also maybe check ebay. 

Posted: 10/11/2014 3:03:25 PM

From: züriCH

Joined: 3/15/2014

hi tinkeringdude,

i had troubles to find a good mic flange too. so i drilled a hole in the bottom of the case and glued with araldit (real good stuff. it's been used to glue the ramses temple in egypt with it, after he relocation of it. so good enough for a theremin i guess and its solid in 5min.) one of those http://www.musik-produktiv.ch/k-m-217-reduziergewinde-mit-raendel.html into it. 

as for the case screws: i never really understood the (electro-tech)function of the ew-case screws. but they are toobig, for only the carpenter-work.

btw: i think here one can find cool knobs, lights etc. here: http://www.musikding.de

gutes gelingen.;-)

Posted: 10/11/2014 3:05:36 PM

From: Northern NJ, USA

Joined: 2/17/2012

"Is the placement of screws in the case critical? I guess I'd opt for the smallest screws that could possibly hold it together, with some wood glue also."  - tinkeringdude

I think the taboo against metal in the general vicinity is rather overblown.  You don't want to tune or play your Theremin with it resting on a metal desk, but a few metallic screws holding the wooden case together shouldn't make a whole lot of difference.

IIRC I bought a mic flange off eBay.

Posted: 10/11/2014 6:01:00 PM
RS Theremin

From: 60 mi. N of San Diego CA

Joined: 2/15/2005

Mic Flange from PartsExpress, they ship to Germany, might be good?



Posted: 10/11/2014 7:50:37 PM

From: Germany

Joined: 8/30/2014

PartsExpress - shipping costs more than double of what two of those items cost, thanks anyway :-)

xtheremin - yes, musikding is great :-D I bought a good batch of retro knobs when some imperfect ones were on sale some time ago. Alas my synth project ate most of them, hehe.

I hope I'll find the right things n the hardware store for the antenna sockets - xtheremin, you don't happen to know the German names for such kind of things? :-D Getting the really correct "in trade" translations for things like that, which a guy at the checkout will know when I ask, is quite hard using normal dictionaries from my experience...

Chobbs - you could be right, I'll theck that!

About the glueing of the adapter into the wood, that sounds strange to me, also hard to get straight?
If the stuff smells strongly I object already ;-) (yes, yes, I am one weird tech guy whose nose is easily offended by industrial chemicals of diverse variety, even stuff others don't smell anymore and think "it's evaporated by now" - no, not really :-P )

Posted: 10/11/2014 8:17:16 PM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

Hey Tinkeringdude -

Those flanges / adapters are a right royal pain in the rear! - The thread isnt common so most engineering firms dont have tap/ die to suite, they have been a hardware battle of mine for ages.

The last time I needed something similar (only I needed flush mounting) I found it cheaper to buy a microphone stand with locking rings of the right thread! - took these two rings off and bolted them to the bottom of the equipment.

So if you do find a low cost source of anything suitable, please let us know - I have been thinking about buying the required tap so I can get a local engineering firm to cut some basic flanges to screw into a case, but the outlay is too high right now.

I think I got my last ones from Amazon, but they were £8 each (?)


You may find it easier / cheaper to tap a 3/8" and put an adapter in:



Posted: 10/11/2014 8:56:20 PM

From: züriCH

Joined: 3/15/2014

tinkeringdude, it's called "flansch". but i never found one here around. thats why i did it my way. araldite is not very smelly, but you need some skills to do it properly. like put it all together on a mic stand, without glueing all together. ;-)  a real tinker job , but we had plenty of these reductions around and i don't have two left hands, fortunately. edit: just saw, that you aked about the antenna construction! i guess you can find coppertube and the fittings for that in a "baumarkt". either in the plumbing or the gas section. you might need coppertube anyway. and if you like the moog look...

Posted: 10/12/2014 11:06:37 AM

From: Germany

Joined: 8/30/2014

Hmmmm, for the pitch antenna one could use a banana jack, then a banana plug with a brass rod, 3mm or so that just fits in there - then coated with some foamy stuff that brings it to the necessary 10mm, and then the outser surface would have some metallic coating which is not too brittle so it would break when the foam is pressed together by hand.

I don't have the slightest idea how this would be achieved - but a thing as light as that may well be held in place by just a tight banana plug. Not the primitive ones, but those with some more "springy action". Aaaah, seems they are called "bunch plug" bunchplug(and the outer hull must be connected to the core somehow obviously)

Posted: 10/12/2014 3:08:34 PM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as WaveCrafter.com . ...................................

Joined: 12/7/2007

6.35mm metal jack plug does this great! Just connect the ring on the socket to the antenna connection, shove the jack into the appropriate sized conductive tube (ID of tube = OD of plug) and use conductive epoxy if you need to.

Posted: 10/27/2014 7:54:44 PM

From: Germany

Joined: 8/30/2014

Hey, if I find a plug with not too big of an outer diameter I actually might do this - although you'd need a real good quality jack for that, so you don't trash it when accidentally applying a sideways force, no? Such an antenna looks like quite a mean lever to me.

Well, different maybe-problem now.
So past weekend I got to solder most parts onto my main board. Including those adjustable coils from ebay. Now I found a thread where Thierry mentioned that the toko things are adjustable +/- 14% I think. Oops. The coils I found are said to be* adjustable 45..100µH, which is kinda more than that.
Does this mean that, since a tiny movement of the core in my coils changes inductance considerably more than in the toko coils, that setup / tuning of my instrument will be certain hell?
(not there yet to just try it - front panel and "EQ coil" boards are TODO, not to speak of housing and antennae)
Are there things I can do to alleviate that, other than getting the exact proper coils? I was thinking of actually opening the cans, removing half** the wire and putting a 47µH fixed coil in series like the "hotrod" schematic shows... (*if* I can get that on the board somewhere still), may be messy though.

* the seller gave some other inconsistent info on his stock of coils, so no idea how accurate this is.
** not quite half of course, the seller gave a graph for max inductance over number of windings - let's hope it's accurate

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