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Re: The Theremin / DRSSTC Project
Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
Hi again Dan,
I tried the ThereminVision II digital robot controller near the SISG
coil. The readback signals were totally scrambled. No lasting harm
done. I feel there is little hope there... The D-FlipFlop
heterodyne circuit will pick up the coil's fundamental like crazy and
the digital filter is just an average circuit that will rip at super
high speed near a coil. One "might" be able to program the noise out
with the microcontroller, but that is a far reach... The fundamental
frequencies of the sensors are about 2MHz but all the digital
electronics has nothing to "filter out" the coil's powerful
oscillations as they get mixed in too.
The circuit did go up against a handleld Tazer armed robot in a
competition and did fine until the Tazer "connected" and knocked out
three sensors (150kV vs. 555 timer input pin...). But those signals
must be a single sharp HV spike that just did not register RF wise,
unlike a heavy oscillating DRSSTC signal. But the poor crippled
robot did win due to human error latter :o)))
I did not try the Moog Theremin since I am not sure how well
protected it is and I did not want to risk frying it. But just the
"noise" should play havic with the amplifiers in it at any rate. The
antennas for pitch and volume are direct connected to the "guts". I
think there is a schematic for it on the net "somewhere".
So I am afraid that I can't help much, and it basically looks very
"bad" :-( I am sure a Theremin type circuit "could" work, but it
would be difficult and just off-the-self ones are probably hopeless.
The big problem is to measure the sub pico-Farad effects of ones hand
near the antennas while that 350kV ~150kHz DRSSTC monster is playing
15 more feet away. Theremin circuits use fairly high frequencies
close to the DRSSTC, so "filtering" is almost impossible.
The are optical versions of the Theremin that may have much more
hope, but I am not familiar with them.
Hope this helps, or at lest is a clue to the problems that await.
There is a digital solid state and public domain theremin version here:
You can wire the basic circuit on a breadboard in about 1/4 hour.
The problem will be that the capacitance antennas will pickup the
voltage off the top terminal of the coil just like a length of wire
or plane wave antenna:
You can easily model the thing in microsim to determine how bad that
will be. You will want to add a TVS across the antennas to
ground for sure which will not affect the function.
The voltage off the coil will appear as a valid signal but might
very well be cancelled by the counters and anti-jitter
stuff. Probably not to hard to filter for relatively low speed hand
movement in this case.
I have digital demo board of the above and a Moog theremin I could
try out if you need. I would think the digital version would be vastly better.
At 08:55 PM 6/28/2006, you wrote:
Watching an old sci-fi martian movie this past weekend has inspired
me to explore the possibility of using a Theremin device to control
the output of a DRSSTC system. I plan on designing
a system which can independently control both pitch (PRF) and arc
length (volume) of the DRSSTC by simply moving your hands around
the Theremin device. The only question mark is
how it will interact with the fields generated by the DRSSTC
itself. That i won't know until i actually build the device and do
the testing. I'm keeping my fingers crossed, so if it works, it
will be pretty damn sweet!
For those who don't know what a Theremin is, here is some
information here on it: