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Re: Poulsen first light
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:
First time I downloaded it the whole file didn't come through. I
gather you are trying to use a very high >2 kV voltage source for your
arc. That won't do at all for such a device. A very small arc
oscillator I built here a number of years ago ran about 1 amp from
rectified 120 volt line, using a 100 watt lamp as a series ballast.
Once the arc was struck the voltage across it drops to around 20 volts
average. Got the thing to put out a bit of power at 300 kHz, and it
would oscillate (sort of) up to about 2 MHz. Sometime I intend to
resurrect it and do it right.....
Suggest you contact
David Quinlan
poulsen-at-mail.hicom-dot-net
A year or so ago he was building a rather good arc oscillator, and might
be willing to share details with you. For general information on the
subject you might want to start at this web site:
http://home.luna.nl/~arjan-muil/radio/poulsen.html
Bottom line is that I would expect your arc to be happier running a few
amps at 200 VDC or less, with some sort of regulator to keep the spacing
right. You will need a suitable ballast, of course.
Ed