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Re: Listening to TC?



Original poster: Bob Wroblewski <bwroblewski@xxxxxxxxx>

I actually built a couple of the bat detectors, from the following link, as a diversion when the bats come out at a cottage near a lake. Used them all summer long, great fun around the camp fire pit. I wanted to bring them to Ed's Teslathon but didn't go this year.
<http://pw1.netcom.com/~t-rex/BatDetector.html>http://pw1.netcom.com/~t-rex/BatDetector.html


I listened to a cheap plasma globe and within 10 feet it whines continuously. It fades out quickly at longer distances. I suspect it is flyback transformer switching frequency noise directly.

Then I listened to an Electro-Technic Products model BD10-AS vacuum tester wand (a kicker coil) that gives less than 1" spark discharge. It produces a raspy noise that sounds very much like what is heard with ears only. My table top and medium size Tesla Coils are presently disassembled, so other ultrasonic measurements with classical NST/spark gap TCs await.

Bob Wroblewski
Dracut, MA

Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: William Beaty

On Sun, 4 Sep 2005, Tesla list wrote:

> Original poster: Jerry Chamkis
> the one you really want. They behave just like an ordinary capacitive
> transducer, the polarizing voltage is typically 200 v. You can find a
> (very!) wide spectrum of B&K instruments quite cheap but the capsules hold
> their value depressingly well. It wouldn't be hard at all to build a
> heterodyne listening-box. I think such things (although presumably NOT with
> B&K capsules :-) are still used for detecting insects.

The cheap and crude version:

http://pw1.netcom.com/~t-rex/BatDetector.html

http://home.kabelfoon.nl/~bertrik/bat/

http://www.goldmine-elec-products.com/prodinfo.asp?number=C6897

http://www.goldmine-elec-products.com/prodinfo.asp?number=C6899

http://www.goldmine-elec-products.com/prodinfo.asp?number=G951&variation=&aitem=9&mitem=9


> > sounds, but what about "ultrasounds"? These would be sounds from 15KHz on > > up to the resonant frequency of the coil. This question is prompted by the > > following: Last night, a bat got into the instrument/people section of the > > lab. (The TC section is inside a grounded 10ftx10ftx8ft cage). With the > > coil running, the bat ran into the wall the way a bird or insect will beat > > against a window trying to get out. I turned off the coil and it > > immediately turned around and flew back out the door which was only open > &g t; about 5 inches. Makes me think maybe the coil was making sonar-jamming > > noises. Of course, it could be pure coincidence.

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William J. Beaty SCIENCE HOBBYIST website
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Seattle, WA 206-789-0775 unusual phenomena, tesla coils, weird sci