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I vividly remember, from years ago, seeing a display which was a row of blue
lights along the top of a catfish tank, like a large audio level meter. The
discharges from the catfish made the meter light up, left to right,
depending on the strength of the discharge. It was accompanied by a
sine-wave sound generator, higher frequencies being higher voltages.
A workable analog voltmeter will probably be small and dim. Remember also
that many children have never seen an analog readout and will not know to
look for a moving needle.
What I don't remember so vividly is where it was; I believe it was at the
aquarium in Baltimore.
Marc Taylor
Coordinator, Andrus Planetarium
Hudson River Museum
511 Warburton Avenue
Yonkers, NY 10701
(914) 963-4550 x223
Fax: 963-8558
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-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]]On Behalf Of Paul Allan
Sent: Thursday, December 04, 2003 11:07 PM
To: [log in to unmask]
Subject: Electric Catfish
ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related
institutions.
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Recently we received the donation of an African electric catfish
(Malapterurus electricus.) It is about 25-30 cm long (10-12 inches) and is
being kept in a 55-gallon freshwater aquarium. Besides telling the
interesting facts about this unusual fish in signage, we would like the
display to have a bit more pizzazz.
There are conflicting reports on whether the fish uses it's electrical
discharges for navigating or just for feeding, but as far as we have
determined, using a digital multimeter, it can produce about 2-3 volts when
feeding and does not register any discharge when swimming around it's tank.
We used alligator clips to attach two stainless steel wires to the
multimeter probes, put the wire into opposite ends of the tank, and fed the
fish a small feeder goldfish. Adult fish of this type (over 1 meter in
length) are reported to produce up to 350 volt discharges.
We would like to have visual and auditory events occur when there is a
discharge. We've thought of a large, analog galvanometer/voltmeter. We
would also like to have a light turn on and/or a buzzer sound. The light
and buzzer would not necessarily need to be powered by the electrical
discharge, but the discharge should stimulate the lighting of the light or
buzzing of the buzzer.
Has anyone had experience with this kind of display? Please lend us your
expertise or point us to resources we can use to determine the easiest route
to make this a great exhibit. We know we can turn to local electrical
engineers/electricians, but I thought I would ask the list first to see if
we could get a head start on the project.
Thanks- Paul
*********************
Paul J. Allan
Palouse Discovery Science Center
Pullman, WA
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