Re: DC power
Subject: Re: DC power
From: "SROYS" <SROYS-at-radiology.ab.umd.edu>
Date: Mon, 27 Mar 1995 10:06:09 EDT
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> Is there anyone out there running a large Tesla coil (in the 2 kva
> range) on DC power?
There was "member activity" article in the TCBA newsletter a year or
two back that featured a DC powered coil. The primary was powered by
a couple of microwave oven transformers that were rectified and run
through a voltage doubler circuit (if my memory serves me right).
There was also a lot of inductive ballast used to keep the xformers in
line and I seem to recall discharges in the 30"-40" range. If you're
interested, I'll find the year/volume reference for you.
I've been wanting to try some DC experimentation also. One interesting
feature about DC is that you can use practically any HV-DC supply with
a very large primary capacitance since you don't have to charge your
capacitor to breakdown voltage in the 1/120 of second available before
an AC supply would reverse polarity. I've seen this described as an
"Impulse Tesla coil", but I have no idea how it would perform. I would
imagine that a low-rep rate, extremely high current pulse from a large
capacitor in the primary would give some interesting effects from the
secondary. I would also imagine that quenching could be problematic.
This might be a good candidate for a bi-polar coil with a single turn
primary? One thing to remember is that with a DC supply, your
capacitors WILL be charged to a lethal voltage when you turn the power
Has anyone read the book from L. Anderson reviewed in the last TCBA
newsletter about one of Tesla's "lost" lectures? The review talks about
(relatively) long sparks with only 10 VA input!
Well, hamfest season is upon us again. The first large show in my
area was this past weekend and a good time was had by all. I spent
the better part of Saturday lugging around about 60 lb of what I though
were high voltage transformers, only to get home and find out that one
was a 30 pound boat anchor and the other was an isolation transformer
(120V in - 120V out) good to 40 kV isolation. Oh well. On the brighter
side, I found that used RG8 solid core coax was very cheap (I got about
a hundred feet in various lengths for $8). A lot of people had it for sale
and there were some who were practically giving it away! I also picked
up some RG9B - it looks similar, but I'm not really sure what the
differences are. Any input as to what the numbers really mean?
Steven Roys (sroys-at-radiology.ab.umd.edu)