the "noisemin" ??

Posted: 5/24/2006 8:31:06 AM

From: brussels

Joined: 2/15/2006

Hi there
I finnaly bought it, the theremin from silicon chip, australia.... I'm using it for an examination assinment, i'm studying radio and for this project i want to connect a theremin to a series of metal plates wich will vibrate as someone get's near them... BUT.. before that happens i should get my theremin to

Here's the problem

First of al I got besides a quite nasty hum no tone, BUT when yesterday i connected the final wires i got for one instant the sound, i then touched case and it was gone.

I didn't used the pins that where in the case for connecting the wires and the case, I directly solderd the wires to the case, is this a problem?
Also, i don't measure a voltage on pin1 of IC2..., yet i measure everywere a nominal 6V.

Do yo know the problem ore even better.. the solution??

thanks a lot!!

Posted: 5/30/2006 7:41:33 AM

From: UK

Joined: 5/16/2006


OK - I've just finished building one myself, and am about to embark (hopefully, whenever I get time...) on the modifications that are listed on this site (one of the articles). I got a bad lot of hum off my power-adapter - but as I read in the instructions - earthing the case of the volume Potentiometer REALLY helped.

When you say that you 'soldered the wires directly to the case' what do you mean? If you mean that you wired directly to the PCB, without using the gold pins supplied, that shouldn't cause the issues you've been having. HAve you tried tuning the theremin with the Ariel lower? (only 2 or 3 segments out)-this will affect the capacitance around the ariel, and I've found that the shorter the ariel, the smaller the field around the Theremin pitch ariel is).

Also, you could have a bad solder joint/short circuit (although given you're getting a nominal 6V, I think that's unlikely). HAve you tried fiddling with V2/T3/T4 to see if the volume oscillator is working as it should?

Hope something there helps, but bear in mind, I am by no means a whizz @ Electronics!

Have fun.


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