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Re: VARIAC QUESTIONS
to: Ron
A variac is an adjustable autotransformer. It works on the principle on
which all iron core transformer work: primary potential x primary current
(input power) is equal to secondary potential x secondary current (output
power) minus the usual losses such as magnetising forces, heat losses, etc.
This is in effect a turns ratio device and an adjustable carbon brush
allows you to continuously vary the turns ratio of the transformer, hence,
the variable voltage output. The voltage rating of the variac depends on
the insulations used in the constructions and the max turn to turn
potential. The current rating is determined by the guage (diameter) of
wire used in the construction. A home made variac can work but it's a lot
of work to make it while they are reasonably inexpensive thru surplus
outlets. The circular core of laminated silicon steel would be hard to
fabricate without great difficulty. Nameplate current can usually be
exceeded by 10-15% for short duty cycles as in Tesla oscillator primary
transformer controls.
DR.RESONANCE-at-next-wave-dot-net
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: VARIAC QUESTIONS
> Date: Thursday, September 03, 1998 7:24 PM
>
> Original Poster: "RONALD QUIRING" <ronrenee-at-hotmail-dot-com>
>
> CAN ANYONE BRIEFLY DESCRIBE HOW A VARIAC DOES WHAT IT DOES? WHAT IS IT
> IN A VARIAC THAT DETERMINES ITS VOLT AND AMP RATING? AND THIRD: DOES
> ANYONE HAVE ANY THOUGHTS ON A HOMEMADE VARIAC ????
>
> THANKS MUCH
>
> RON QUIRING, CAMBRIDGE ONTARIO.
>
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