Re: Listening to TC?

["Tesla list" <tesla@xxxxxxxxxx>]

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.

(((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))
William J. Beaty SCIENCE HOBBYIST website
billb at amasci com http://amasci.com
EE/programmer/sci-exhibits amateur science, hobby projects, sci fair
Seattle, WA 206-789-0775 unusual phenomena, tesla coils, weird sci