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Re: Triac-dimmers in TC's
In a message dated 2/27/99 4:21:16 AM Central Standard Time, tesla-at-pupman-dot-com
writes:
Gary
I have used triac control for AC/DC motors and induction (permanent split
capacitor) motors. The schematic is in T.C.B.A. News vol. 17, #1.
It uses an SK-3659 15 amp 400 volt triac in a simple "lamp dimmer type"
circuit with a snubber consisting of a 100 ohm resistor and .22 uF capacitor
in series accross the triac. The output is fed through a conventional E.M.I.
filter to the motor.
There were never any run away problems or glitches in operation even running
in a wooden enclosure.
For a long time this controlled a 1/3 H.P. induction motor in a 10 kW setup
without flaw. The drawbacks I had were with larger motors that were heavily
loaded pulling too much current at start up blowing the triac. Also I had a
direct strike to the motor once and it took out the E.M.I. filter with triac.
The good news is the triacs are cheap to replace. I believe I bought the
traics thru All electronics mail order and the 20 amp Cornell-Dublier filters
from MECI mail order.
Kevin E.
> Has anyone had experience using a solid-state off-the-shelf lamp dimmer
> to control the speed of a motor in a Tesla Coil? I'm currently using a
> variac on my gap's vacuum cleaner motor, but I thought I'd save some
> space and just use a solid-state dimmer. The motor is an AC/DC
> "universal" type. I'm just wondering if the voltage spikes and
> interference would either toast the semiconductors or confuse the control
> circuit. Please don't speculate and suggest using a filter unless you
> know, from experience, that it won't work without it.
>
> Thanks, Gary Lau
> Waltham, MA USA
>
>
>
>
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