Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!rutgers!usc!trwind!venice!greene
From: greene@venice.SEDD.TRW.COM (John Greene)
Newsgroups: sci.electronics
Subject: Re: Anyone know about arc generators? `ffzzapp'
Message-ID: <288@venice.SEDD.TRW.COM>
Date: 1 Feb 90 19:11:15 GMT
References: <2813@goanna.oz.au> <5170071@hplsla.HP.COM> <4079@jarthur.Claremont.EDU>
Reply-To: greene@venice.sedd.trw.com (John Greene)
Organization: TRW System Engineering and Development Division
Lines: 39

In article <4079@jarthur.Claremont.EDU> rspangle@jarthur.Claremont.EDU (Randy Spangler) writes:
>I understand how transformers work fine (I've had E&M).
>
>But how do you get the high frequency with that much voltage?
>I've seen pictures in Edmund Scientific and such, and it doesn't look
>like too much circuitry is involved.

The primary of a transformer is used as part of a tank circuit that is 'rung'
with an impulse generated by a spark gap.  You need some sort of high 
voltage source from either a neon sign transformer or a voltage multiplier
circuit that provides high voltage DC.  It looks something like this:

	 HV source---------| |--------|------) (-------O output electrode
			 spark        |      ) (
			   gap   CAP ---     ) (
				     ---     ) (
				      |______) (
			              |	       (
			     	      GND      (
					       (
					       (-------|
						       |
						       GND

When the spark jumps the gap it rings the tank circuit at it's resonant
frequency.  Usually several hundred Kilohertz to a couple of Megahertz.
The capacitors are made several different ways but the most common seems
to be to use a double sided PC board and etch away the copper from the 
edges a quarter of an inch or so.  The size of the board will determine 
the capacitance.

The secondary has as many turns on it as you have wire.


-- 
John E. Greene    "People are just like frankfurters....You have to decide
                   if you're going to be a hot dog or just another wiener" DLR
TRW Systems Engineering and Development Division
ARPA: greene@venice.sedd.TRW.COM  USENET: ..trwrb!venice!greene