silicon chip - help!!!!

Posted: 4/3/2005 4:12:34 PM

From: sweden/ireland

Joined: 4/3/2005

Can anyone help,

I bought the silicon chip manage theremin, bu it i'm pretty new tot he elctronics world. I managed to finally assemble the theremin and then progressed to the instructions for setting it up, but i am not getting any results from the theremin.

I applied power with a 9v DC (400mA) adaptor and checked for the 'nominal' 6v between the casing of T1-T4 and pin 8 of IC2 but there is not a flicker on the voltmeter; Pin 1 and 2 register about 5 volts and pin 4 and 6 about 3.

So I checked;

every connection = ok
took out IC1 and checked it = ok
checked current at adaptor = ok
checked soldering = seems ok ( there is a slight solder bridge underneath between pin 4-6 of IC2, but these are joined on PCB anyway!)

The speaker is hissing and there is a little interference when i take voltage readings so this inidicates it is responding.

Do you think the adaptor is ok despite it being 400ma?
There is current there but im not getting the desird output. I know its a lot to take in but did anyown have similar problems or could give me some advice?


a worried K-dawg
Posted: 4/24/2005 1:28:41 PM

From: UK

Joined: 2/21/2005

Hi there.

if you have the same construction instructions as I have, it mentions the sensitivity of VR2. Don't underestimate this statement. If you can, I'd reccomend using a multi-turn trimmer in place of the one supplied.
Then use Max's tuning instructions.

You may have to play aroud with T2 AFTER adjusting VR2 and T4 to get an output.

Good luck


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