Re: Poulsen first light

["Ed Phillips" <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Tesla list wrote:
> 
> Original poster: "Michael H Nolley" <nolleym-at-willamette.edu>
> 
>     Greetings!
>     Today I tested my Poulsen Arc TC for the first time.  The results
> weren't spectacular, but I still have some kinks to work out.  Here are the
> specs.
> 
> Supply:  2000vac 1A Mot (very large), rectified and filtered through a 41 mf
> 2kvdc capacitor, and a 100kv L diode filter for transients.
> 
> Gap:  Poulsen Arc gap, consisting of a 1 inch diameter water cooled copper
> electrode, and a 3/4 inch diameter graphite electrode.
>     At right angles to the gap are two modified Mot cores ("E" cores) which
> contain 2 Mot secondaries each, for a total of about 8000 turns.
>     The center leg and one of the side legs of both E cores are extended
> into the chamber by laminated pole pieces ("I"s).  The center legs are the
> operating pole pieces, and consist of short "I"s.  They terminate with nomex
> insulated NIB magnets just short of the gap.  The side legs, which are on
> the bottom, are connected with two complete Mot "I"s, which run directly
> under the gap.  These complete the magnetic circuit.  The second side leg of
> both Mots is unused.
>    The whole apparatus is lashed together with PVC insulated copper wire,
> since I couldn't find a way to weld the Mot cores to the pole pieces without
> losing the ability to change inductors, and without melting the chamber (an
> HDPE bucket).
>     Eventually, when low power tests are over and I have found the proper
> metal chamber I may weld them.
>     A small alchohol lamp sits on the bottom pole piece and burns in between
> the gap, supplying the hydrogen atmosphere.
> 
> Cap:  2 1600V .01mf Panasonic caps in series.
> 
> Primary:  8" diameter helical primary, using 16ga.  PVC insulated wire.  21
> turns max.
> 
> Secondary:  6" diameter 26" long secondary, resonant frequency around 330khz
> unterminated.
> 
>     I started out by limiting the supply power with a 10k resistor--this is
> the only way I could run it without tripping the breaker.  The gap wouldn't
> ignite at all--I would move the graphite electrode into contact with the
> copper one, and there'd be a "chirp" and then nothing.  Depending upon the
> capacitor size I'd get anywhere between 1 inch and 2 inches during these
> moments.  I think the culprit is the inductors and possibly the
> resistors--not enought current is getting to the gap to sustain the arc.
> The first thing I'll try is limiting the primary side of the Mot instead of
> the 10k resistor.  Then I'll probably cut each inductor down to 1 Mot
> secondary--and if this doesn't work I'll try primaries.  I'm afraid this may
> be too little inductance, however.  Another possible route is higher
> voltage, which I may try even before this.  I have five more 2kv 1A Mots
> which I can configure for 8kv 1A (without doublers).  In the next day or so
> I'll be doing higher voltage runs, and I'll keep the list updated.
> 
>             --Mike

Mike:

	Very interesting but can't figure out just what kind of a power supply
you are using to feed the arc.  Are you trying to feed it with high
voltage from the MOT's?  How about more details?  Would think a small
arc like that might work at two or three hundred volts DC and several
amps.  By the way, if I were doing it I'd just play with the primary
circuit until I was getting plenty of power (hundreds of watts) into it,
then play with adding the secondary.


	You're capacitor sounds pretty small.  What frequency are you shooting
for?  I'd think that a hundred kHz or so would be just about right.

More!

Ed