[sci.electronics] Electronic Pest Control

fgk@well.UUCP (Frank G Kienast) (07/17/89)

> thousands upon thousands of dead cockroaches could be found.
> The dead mass of *** YUCK *** interfered with the crossed taught wires
> (Strain guage) -thereby producing erroneous measurements.
 
> WHY ? Well, after a little research they discovered someone who affirmed
> that the resonance or vibrations on these wires caused by (lots of
> verbage) produced a 14KHZ sound wave. This just so happens to be the
> mating frequency of la cucharacha..the despised cockroach.
 
Then wouldn't cockroaches also be attracted to TV sets?  TV sets produce 
sound at 14.7KHZ.
 
In real life: Frank Kienast
Well: well!fgk@ucbvax.Berkeley.EDU
CIS: 73327,3073
V-mail: 804-980-3733

davidc@vlsisj.VLSI.COM (David Chapman) (07/19/89)

In article <12726@well.UUCP> fgk@well.UUCP (Frank G Kienast) writes:
>> [stuff deleted]
>> verbage) produced a 14KHZ sound wave. This just so happens to be the
>> mating frequency of la cucharacha..the despised cockroach.
> 
>Then wouldn't cockroaches also be attracted to TV sets?  TV sets produce 
>sound at 14.7KHZ.
> 
U.S. TV sets scan at 15.75 kHz, not at 14.7.  The flyback transformer tends
to whine at that frequency (drives me nuts if it's too loud).
-- 
		David Chapman

{known world}!decwrl!vlsisj!fndry!davidc
vlsisj!fndry!davidc@decwrl.dec.com

davidb@cognos.UUCP (David Borowski) (07/19/89)

In article <12726@well.UUCP> fgk@well.UUCP (Frank G Kienast) writes:
stuff about scale deleted.
>Then wouldn't cockroaches also be attracted to TV sets?  TV sets produce 
>sound at 14.7KHZ.
> 
>In real life: Frank Kienast
>Well: well!fgk@ucbvax.Berkeley.EDU
>CIS: 73327,3073
>V-mail: 804-980-3733

I don't normally correct but! tv horizontal scan is 15750 HZ 30*525 scan lines
and as a blind person i don't watch the stupid thing anyway.  bad info
does everyone a disservice.  so before things go on the net
check that the data is correct.  I depend on verbal and online communication
for my memories data base and don't need to fill it with junk!
-- 
David Borowski           Cognos Incorporated     S-mail: P.O. Box 9707
Voice: (613) 738-1338 ext 5555                           3755 Riverside Drive 
  FAX: (613) 738-0002                                    Ottawa, Ontario 
 uucp: uunet!mitel!sce!cognos!davidb                     CANADA  K1G 3Z4

ISW@cup.portal.com (Isaac S Wingfield) (07/25/89)

David Borowski writes:
I don't normally correct but! tv horizontal scan is 15750 HZ 30*525 scan lines 

Well, actually, this is correct for B&W only, and we don't get much of
that any more...

The horizontal scan rate for NTSC color is 15734.26 Hz or thereabouts.
The vertical rate is 59.94, and both are exact submultiples of the
color subcarrier, at 3579545 Hz.

The reasons for this have to do, at least partly, with attempts
to minimize interference between video and audio by controlling
the video signal spectrum. By locking everything together, most
of the energy is in a "comb", and the sound subcarrier fits neatly
in between.

Regards, Isaac


isw@cup.portal.com