Report - Dimmer as a Variac.

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi All,

I wired up the dimmer and hooked it to a 250 watt light bulb and got the
following voltage waveform:

http://hot-streamer-dot-com/temp/250W-R.gif

The dimmer is holding off the voltage turn on until what appears to be a
timer triggers it to turn on.  The dimmer remains conducting until the AC
reaches zero volts (perhaps amps).

I then hooked the input of my small coil in parallel with the 250 watt
light and tried again:

http://hot-streamer-dot-com/temp/250W-RandSTC.gif

This is the voltage waveform I caught but the 2.5 amp fuse on the coil's AC
input protection blew right away.

I wired in the Pearson current monitor and tried again with a 4 amp input fuse:

http://hot-streamer-dot-com/temp/VandI.gif

Looks like I am getting current spikes...  Big ones...  At first I though
the MOVs where clamping voltage spikes but the fuse is on the other side of
the MOVs and the peak voltage is lower than the MOV clamp voltage.  Also,
some of the lower voltage peaks are getting just as big of current spikes.

I clicked the gain down and tried again to see how high the spikes are:

http://hot-streamer-dot-com/temp/VanI-2.gif

Only 58 amps!! =:o

I suspected the 60uF of PFC caps are not getting along with the sudden
dimmer voltage turn on which is about 180 volts.  So I pulled the
connectors off the caps to take them out of the circuit and tried again:

http://hot-streamer-dot-com/temp/NoPFC.gif

Neat!  The fuses don't blow and the current and voltage are reasonable now
:-))  There are still 11.8 amp current spikes which may be due to the
capacitors in the small coils dual stage line filter:

http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/small_ACwiring.jpg

I can hear high voltage on the NST output with just the NST protection
circuit attached.  The input voltage spikes may be pumping high voltage
spikes onto the output too.  I will have to hook up the high voltage
fiber-optics to check that but that may not be a problem once it is hooked
to a primary cap.

So PFC caps cause big current spikes with he dimmer's sudden turn.  The
output voltage seem to be mirroring the input signal giving high voltage
spikes on the NST output at a low power setting on the dimmer.  The line
filter may be also causing current spikes, but small ones.

Sort of bad not to be able to use PFC caps but the output spikes should not
be a problem and the line filter perhaps can be moved before the dimmer or
those spikes just ignored. 

Some additional pics of the "stuff" are at:

http://hot-streamer-dot-com/temp/P7070006.jpg
http://hot-streamer-dot-com/temp/P7070007.jpg
http://hot-streamer-dot-com/temp/P7070008.jpg

Thanks to Brain for letting me use his fiber probe that I have back here
for some "factory repairs" ;-))  I left mine on and toasted the batteries...

The science goes on...

Cheers,

	Terry