[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: diode used against RF? (fwd)



Original poster: "Basura, Brian" <brian.basura-at-unistudios-dot-com> 

All,

I started experimenting with a DC charging circuit in the Fall. The
following URL lists my experiences to date:

http://fp2.hughes-dot-net/brianb/dc.htm <http://fp2.hughes-dot-net/brianb/dc.htm> 

I plan to get back to it after the holidays.

Regards,
Brian B.

		-----Original Message-----
		From:	Tesla list [mailto:tesla-at-pupman-dot-com]
		Sent:	Thursday, December 07, 2000 3:16 PM
		To:	tesla-at-pupman-dot-com
		Subject:	RE: diode used against RF? (fwd)

		Original poster: "sundog" <sundog-at-timeship-dot-net> 

		Hi all,

		  I've run my NST's in a DC setup.  Firstly, you've got to build the strings
		at *least* 2x the voltage to run it more than a second or so.  I recommend
		3x as a strong minimum.  10mohm bleeders across each diode seemed to help
		them live longer.  I use the 1kv1A (4007's) frum digikey.  1000 cost me
		~$40, i believe.  You get a pretty ripply DC off it, but it's DC and charges
		caps just fine.  For larger applications, I'd derate current to 1/2 on them,
		as even on my 180ma NST farm they got warm after long runs.

		On the input side (mains) I noticed less fluctuation of the input current
		than running AC, and it seemed more "well behaved" as far as current draw.
		Not much less overall, just a bit smoother.  Any difference in performance?
		Not really.  I think the diodes and resistors burned up some power, but not
		enough to matter.  Though you eliminate reso-charging, so you can unplug
		your rotary and let it spin down.  Pretty cool.

		  But, I don't think these diodes are fast enough to clamp down on an RF
		signal.  I still think that MOV's and a small RC network like the one Terry
		Fritz designed will work best protecting your NST.  Sure, you loose a little
		spark length, but if it took you 2 months to find an NST, you'll want to
		protect it.

		On a PT or pig system, I don't know.  haven't got my pig to try it on yet
		;) Workin on that. maybe someone else has?
														Shad


		-----Original Message-----
		From: Tesla list [mailto:tesla-at-pupman-dot-com]
		Sent: Thursday, December 07, 2000 12:11 AM
		To: tesla-at-poodle.pupman-dot-com
		Subject: Re: diode used against RF? (fwd)


		Original poster: Tesla List Moderator <mod1-at-poodle.pupman-dot-com>



		---------- Forwarded message ----------
		Date: Wed, 6 Dec 2000 23:37:58 EST
		From: Pyrotrons-at-aol-dot-com
		To: tesla-at-pupman-dot-com
		Subject: Re: diode used against RF? (fwd)

		<< i was wondering if a diode could be connected in series with the NST.
		this
		would rectify but wouldn't really affect the charging of the cap
		there wouldn't be any frequencies from the primary circuit getting into the
		secondary of the NST...has anyone tried using a diode???
		any promising results?? thanks in advance.
		M. Bains >>

		Hi M. Bains and All.

		I can almost guarantee that a *typical* diode or rectifier would immediately
		fry in this application.

		A string of diodes in series to is required to get the voltage rating up.
		(you're not going to find a 30kV diode...the highest I've seen in a single
		package is 26kV) Anyhow, if you did this then you'd just be making a DC
		coil....and a number of people have done it. I don't know the overall V
		rating of the diode stacks they use, but it must be pretty dang high. I know
		that people have killed these expensive diode stacks, too.

		I imagine the diodes would protect a transformer fairly well.....that is if
		the diodes can live through it themselves. Does anyone have input as to how
		well a transformer will live in a DC coil? I'm thinking a long time, as the
		rectifiers won't pass current (kickbacks from the coil) when reverse biased.

		I'd say it's a good thought, and it does work to my knowledge. (I know the
		DC
		setup works, but I'm not sure about the transformer protection idea).

		Justin Hays
		KC5PNP
		Email: pyrotrons-at-aol-dot-com
		Webpage: www.hvguy-dot-com