Date: Thu, 09 May 2002 17:51:05 -0600

Author: David Kardelis

Subject: RE: Power Supply


I bought a 40 Amp 0 -20 VDC power supply from MCM electronics. Works great
for magnetic force on wires etc. It was relatively cheap $300 bucks.


David Kardelis 451 E 400 N
Chairman, Dept of Chemistry and Physics Price, UT 84501
College of Eastern Utah
435-613-4201 (fax)

-----Original Message-----
From: Urs Lauterburg []
Sent: Monday, May 06, 2002 2:40 PM
Subject: Re: Power Supply


This is quite a lot of amps you are looking for and even a 25A rated
autotransformer will not be cheap and certainly huge and heavy. Even a
regular transformer for 25A is going to be bulky. You are aiming at a 625W
power supply and of course you can get them, but they will not be cheap.
Another option is to make one yourself but then again the components will
add up as well. The best deal I am sure is, if you can find such a beast as
surplus from an old research lab. I have been able to get my hands at a 10V
100A power supply, a very exotic and heavy piece of equipment but extremely
useful specially to show various B-fields of different current geometries.

Talking about Boise, I wish you all a good meeting and a very pleasant stay
in Idaho. I would love to come, but then again the trip to the US will be
to expensive for our public funding. A year has past since the last meeting
in Rochester and a lot of things have happened. I very much enjoyed my
first attendance to an AAPT meeting and to meet many of you nice physics
instructional resourcers.

My best to you all, have a good time and take good care of yourself

Best regards


Urs Lauterburg
Physics demonstrator
LabVIEW wireworker
Dept. of physics
University of Bern

>I would like to buy a 25 volt 25 amp variable DC power supply.
>It should simply consist of an on-off switch, a high current variac,
>a high current bridge, and a filter capacitor.
>Does anyone know where to get a variable DC supply this simple?
>Most power supplies have lower power and a lot more regulation.
>I don't mind having the ripple on the DC. I want 625 Watts power and low
>Mcmaster-Carr has manual battery chargers that are similar to this.
>But they do not have a variac so they're not variable, and they don't have
>a cap so they produce pulsating DC.
>Does anyone know where to get one like I described?
>Can't wait for Boise!
>Gerald Zani e-mail:
>Manager of Demonstrations phone: (401) 863-3964
>Department of Physics FAX: (401) 863-2024
>Brown University Providence, RI 02912-1843 USA
>Do a little more of that work which you have confessed to be good,
>Which you feel that society and your most Just Judge rightly demand of you.
>Cultivate the tree which you have found to bear fruit in your soil.
>If you have any experiments you would like to try, try them.
>Now's your chance.
>Henry David Thoreau, Journal entry, 1850.