Hi, I am trying to build the EM theremin, using the Bob Moog schematics, I have assembled the main circuit board, but have not attached the antennas or the potentiometers. My problem is that I am getting the incorrect voltage out of the emitters of my of transistors. The collectors, shows 12V which is correct, but the emitters also show -12V not -0.6. Does anyone have any ideas of what could be wrong?
Thanks.
EM builders fascinate me when they can buy the finished EWS board with all the later modern improvements for $96. I am not psychic but somehow I think the ground side of the power is not properly connected in your circuit. This would forward bias the transistors, then you would get .6v
A very dear brother of mine goes by Thaddeus, his first name is Jude. 
Christopher
Hi, thank you very much for your input, its not about buying one, I am trying to build one for a science expo. For my grounding, I have wired a plug and just wired the ground terminal on it and then plugged it into a mains socket. Is that acceptable.
It is quite a rare name it seems.
Thaddeus.
I have wired a plug and just wired the ground terminal on it and then plugged it into a mains socket. Is that acceptable.
Now that sounds scary, but if it works it is ok. I use to do something like that with 115v and ground.
Unplug your creation and put an ohmmeter probe at R1 or R4 and to your ground plug. This resistance should be zero or 1k. If much higher then check ground track from that point to the plug.
What are you using for a circuit board, I bet that is interesting? Any photos?
Christopher
Hi Thaddeus, about this problem you're experiencing, are you sure your transistors are installed correctly?
Very scary. I am essentially a complete novice with the whole circuitry thing, I've already tried to build these schematics twice, both attempts failed due to obvious errors i later spotted, however the circuiting of this one I have done on bread board, and am certain it doesnt have any errors. It does look like abit of a mess (due to my ignorance, as well as the fact it's breadboard) however, no wires are crossing, and I'm pretty sure the circuitry itself is correct. As you can see, for the volume oscillator, I have place a 27uH adjustable and a 48uH fixed, due to the size of the fixed inductor, i wired it in series with the variable, externally to the bread board, I have yet to connect potentiometers and antenna circuits, due to the fact i have little faith in it working with the current voltages am getting from the emitters as well as the voltage I'm getting across the detector resistor (R24).
https://picasaweb.google.com/117514534490937213031/6314616744282735681#6314616743187422690
There it is.
thank you very much for your help and input.
Thaddeus
Wizard are you in the States? Your transistor comment is excellent. Thad what is your part #. Are you using the 2N3904 or a substitute? On different brands the pinout of the emitter-base-collector can be emitter-collector-base.
Measure directly across what you think is the emitter to base to see if .6v shows up.
You can post photos here at TW photo albums
Christopher
Edit: Builders I highly recommend this Volt, Frequency, etc meter. The ac scale is very sensitive and can be used as a field strength meter to tune your antenna circuit. I will elaborate on that at a later date.
Thaddeus said "The collectors, shows 12V which is correct, but the emitters also show -12V not -0.6. Does anyone have any ideas of what could be wrong?"
Yes!!! 0.6 from base to emitter (middle pin to bottom pin). i'm using 2N3904. on my first attempt I did get them the incorrect way round. This time, I am absolutely certain they are correct.
So everything is good now?
Christopher
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