🚀 go-pugleaf

I am looking for pest repellers for a household use.
I am not a biologist, nor a reader of the group.

I have seen two models offered in popular catalogs:

1. Description:
   ... safe ultrasonic waves chase away mice and other common pests.
   range -- 300-500 sq. ft.
   non-toxic, non-polluting, safe for dogs, cats, birds.
   Brand unknown. Price about $10 at a discount.

2. Description:
   ... generating a pulsating magnetic field that will safely and
effectively get rid of rats, mice and soft shell in-sects within walls.
   range -- 2500 sq. ft.
   doesn't affect household pets ( except hamsters, gerbils and other
rodent pets ).
   Brand: Pest-A-Cator. Price about $30 at a discount.

I have also asked around and was told:
  1. A first-hand experience with an ultrasound device for an outdoor use (
battery-powered ): NO EFFECT AT ALL.
  2. A zoologist's observation: a magnetic field makes fly's wings bit with
another frequency so the fly can't fly ( this is the reason why there is no
mosquitos under high power electric lines ).
  3. It is doubtful that any of these devices can affect cockroaches.
  4. Using the devices with a different frequency of the power supply ( in
Europe via a 220v/100v transformer ) -- 50 Hz vs. 60 Hz -- would change the
output frequency, but shouldn't make an impact on the pest-repelling.
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QUESTION: what is known about any kinds of electronic pest repellers ? 
Any information will be appreciated.

I am not a reader of the group, please reply by e-mail only.
I will summarize to the net.

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Nathan Lulov	lulov@math.harvard.edu