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Re: New coil woes Terry Filter
- To: tesla@xxxxxxxxxx
- Subject: Re: New coil woes Terry Filter
- From: "Tesla list" <tesla@xxxxxxxxxx>
- Date: Mon, 09 May 2005 10:55:34 -0600
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Original poster: JBarrett@xxxxxxxxxxxxxxxx
I suspected I was doing something wrong. I actually built a "Greg Filter"
but didn't realize I ordered the wrong caps. I knocked the caps out of the
circuit because I seen a couple of recent posts that said a safety gap is
OK but a full blown filter is better.
I look into a Terry Filter.
"Tesla list" <tesla@xxxxxxxxxx>
05/08/2005 10:42 PM
Re: New coil woes
Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>
You need more than just a safety gap. If you only use a safety gap it is
essentially another primary spark gap connected in parallel with the main
spark gap. This does nothing to stop the RF from getting back into the xmfr
windings --- sure, it clips the overpotentials, but you need to keep the RF
"underpotentials" out of the xmfr windings as well. If not they spiderweb
all over the windings due to their HF nature. Their capacitive nature
enables them to go thru insulation and finally break it down. Terry filters
block this RF and allow mostly 60 Hz to pass.
Use a Terry filter and save your xmfrs.
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
Sent: Sunday, May 08, 2005 2:18 PM
Subject: Re: New coil woes
> Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>
> Describe the protection circuit you are using between your NST and the
> oscillator tank circuit. Are you using anything?
> Dr. Resonance
> > Hello again,
> > I was attempting to fire up my new 4" coil with a 12,000 volt 30 ma
> > The spark gaps started firing hard and fast with just an occasional
> > at the safety gap. Flourescent bulb blinking in my hand and then poof!.
> > gaps slowed way down and no more safety gap action.
> > One dead nst. So I go to my backup nst. 12,000 volts 60 ma. Same exact
> > Same side too!
> > What am I doing wrong here? very discouraged! The safety gap is two
> > of brass stock with a piece of copper pipe between them that is
> > can slide the brass in and out toward the pipe for adjustment.
> > Coil specs
> > Specs:
> > 21" of 22 guage wire on a 4" PVC pipe
> > 12,000 volt 30 ma Neon Sign Transformer
> > 9 pieces of 1" thick wall copper pipes 6" long for spark gap
> > small fan to cool gap 9 pipes 8 gaps spaced very close but not touching
> > Small Aluminum Toroid probably 8" across and 3 to 4 inches minor
> > Safety gap
> > I tried two separate caps 1 is a Universal Voltronics 28 kvdc 0.01 uf
> > filled
> > the other is a GE 0.01 25 kvdc 700 disch/sec
> > I'm also using a variac to control the Neon Sign Transformer
> > Two 8 foot ground rods
> > Primary Flat confiquration 1/4" copper tubing at 1/4 to 3/8" spacing
> > Thanks
> > Jim