New Case question for a deluxe theremin by jaycar

Posted: 3/15/2010 5:32:54 AM

Joined: 3/15/2010

Hey guys this is my first post.

Just waanting to know more about sheilding/grounding of theremins.

Ive got a jaycar deluxe theremin in working order and wanting to retrofit to a wooden box. I was planning on re tuning when its fitted.

But the kit had a large metal plate under the PCB in the jiffy box that was grounded. Just checking if thats a golden rule of theremin shielding or if it was a construction issue.Just there for structural strength. COuld i get away with not having it in the wooden case?

If so for strength i was also thinking of putting it in a cast metal box from jaycar for a different look. If i kept the antennas floating and the case grounded would it work well (even very well if shielding was important) or just make tuning impossible? Especially if the lid was later added.

Any help would be great.
Posted: 3/15/2010 6:00:42 AM

From: Colmar, France

Joined: 12/31/2007

If the circuit is designed to have a grounded plate, that means that this supplementary capacitance has been taken into account during design, you have to keep it.

If you want to switch towards a wooden case there's no problem. Just place a copper or aluminum foil with identical dimensions onto the wooden bottom plate so that also its position and distance relative to the circuit board will remain the same. Connecting this foil to the ground connector of the circuit board is easy: Take a soldering eyelet and screw it onto the foil.

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