Re: Industrial strength dimmer

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "J. B. Weazle McCreath by way of Terry Fritz <twftesla-at-qwest-dot-net>" <weazle-at-hurontel.on.ca>


At 12:20 PM 06/09/01 -0600, you wrote:
>
>Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<CHURCHMON-at-aol-dot-com>
>
>Hi,
>
>Could you post a list of the parts used in this arrangement and possibly 
>a schematic of the setup?  I'm in the process of constructing such a TSG
>and could use the help.!
> 
>Thanks , 
>Mike Church (CHURCHMON)-at-aol
>

Hi Mike,

I found the schematic diagram and instructions at this site:

http://www.neonshop-dot-com/neonweb/nn/tdorr17.html

It tells how to modify a standard light dimmer to bring out a
third lead for the neutral, eliminating the need for the big
"dummy load" resistors as shown in Terry's version.  However,
I did follow Terry's lead in applying some MOV's for an extra
measure of protection, and the big triac I used had a snubber
circuit from its original application which I retained.

In place of the variable resistor and capacitor that came with
the "donor" Leviton dimmer, I used a good quality one meg-ohm
potentiometer and a 0.01 uF. -at- 250 volt capacitor.  This seemed
to give a much smoother control than the original variable
resistor and capacitor did.

The big triac (Q1 in the diagram) that drives the GM HEIC trigger
transformer is a 20 amp unit, but I couldn't cross referrance the
number on it to anything.  Its case is like a TO-3 transistor and
it is not connected to any of the leads, so no mica insulator or
nylon screws are needed for mounting it to the heat sink.

Between the MT1 and MT2 terminals of the triac is a snubber made
of a 100 ohm resistor in series with a 1 uF. 250 volt capacitor,
which is not shown in the schematic above.  The choke coil in the
lead going to the trigger transformer is wound on a toroid which
is about an inch in diameter and has about 50 turns of number 16
magnet wire.

Be sure to check out the info at www.hot-streamer-dot-com and have a
look at the work Terry has been doing, particularly in where the
MOV's are connected.  He's done a lot of work developing this to
the point where we are now, and I simply wanted to try building
a more robust dimmer, plus I wanted to get rid of the big power
wasting "dummy load" resistors.

I'll try to get some pix and a diagram posted later this week.
Good luck with your triggered gap experiments...the more of us
that try them, the more data will be available to share with the
rest of the gang.  Note to Jason...your explanation of applying
the trigger between the first and second segments of your RQ gap
makes sense.


73, Weazle, VE3EAR/VE3WZL

Listening: 147.030+ and 442.075+
E-mail:    weazle-at-hurontel.on.ca
           or ve3ear-at-rac.ca
Web site:  http://www.hurontel.on.ca/~weazle