capacitance problem?

Posted: 1/19/2007 9:19:52 PM

Joined: 1/19/2007

i recently built a theremin (the basic jaycar kit) for and with my son and while it does work, the output is very low irrespective of any adjustments made to the pots. What does increase the volume very significantly is if I half plug in an RCA lead to the output jack or touch the side of the first resistor next to the RCA or the top of the electrolytic caps next to it (on same path). This seems to me to indicate capacitance problems, particularly as the results vary greatly depending on type of lead connected. My son was experimenting with his first soldering and this may have led to over heated caps.
Does it sound like I'm on the right path?
Any help appreciated
Posted: 1/20/2007 8:23:07 AM

From: Australia

Joined: 1/21/2006

Hey there.

I experienced a problem like this when building my Jaycar theremin. What could be happening is the coils aren’t tuned properly. You may be getting a 'false' tone which is very soft. To solve this and to get the 'real' tone you must retune the coils (T1 and T2) so that they are just apart from one another (one higher than the other (T1) and one lower than the other (T2). Since my knowledge of electronics is limited here is an article which will help you with your theremin. I have done all these mods and I recommend them.

Edit: Also check for solder bridges and the like. I have had many problems which have been caused by a tiny bit of solder.


Hope this helps and also makes sense.


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