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Re: Triac-dimmers in TC's



My RSG employs a kind of lamp dimmer to set its speed: the only difference
is that I built it myself (so that I know the triac current handling
capabilities).

You can find the schematics on my web site:

http://www.saunalahti.fi/dncmrc/rsg.html

My RSG uses an "universal motor" too. The dimmer is located inside the RSG
metal box, about 20 cm from its sparks, and everything works fine. The
dimmer potentiometer has got a 4 meters long cable so that I can regulate
the speed from far: it is placed in a plastic little box (with a plastic
knob).

Because there is no feedback between the motor and the dimmer, if you
change the speed you have to wait a couple of seconds before it stabilizes
to the new value. Speed controls used e.g. in electric drills DO HAVE
feedback and I tried to get a schematic of one of those, with no result.
That would be indeed the best solution.

Again, never had any problem with EM or other disturbances affecting my
"RSG dimmer".

Regards





tesla-at-pupman-dot-com on 27.02.99 07:00:08

To:   tesla-at-pupman-dot-com
cc:    (bcc: Marco Denicolai/MARTIS)
Subject:  Triac-dimmers in TC's




Original Poster: Gary Lau  26-Feb-1999 1740 <lau-at-hdecad.ENET.dec-dot-com>

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