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Multi-layered Sec + batt
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From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Wednesday, March 25, 1998 4:01 PM
To: Tesla List
Subject: Re: Multi-layered Sec + batt
Hi all,
Just wanted to add a note about exotic windings:
> From: Alfred C. Erpel (Home) [SMTP:aerpel-at-pil-dot-net]
> Sent: Tuesday, March 24, 1998 6:14 PM
> To: Tesla List
> Subject: RE: Multi-layered Sec + batt
>
>
> > From: Dale Hall [SMTP:Dale.Hall-at-trw-dot-com]
> > Sent: Monday, March 23, 1998 5:11 PM
> > To: Tesla List
> > Subject: RE>Multi-layered Sec + batt
>
>
> > Hi Alfred,
> > I have been using battery power TC's regularily. I use conventional
> > Pri & Sec's, a vacuum switch as a gap (quiet, - the only sound is the
> > HV discharge: nice for the desk, and fast quenching and small ~2x1"
> > "T" shaped - SPDT transmit - receive switch I believe was the
> > original application), and a flyback for HVDC. One of the advantages
> > of DC is that I can select larger value resonant Caps. For example
> > with a .1 uF 5kVdc ruby mica (~2x1x1/8"), Pri=11"x1/8 copper tubing
> > (tap 3-4T), Sec = 8.5"x20 #22, I get 8-10" discharges at 1-2 per sec
> > using 9v batt at 40ma powering a 1" cube flyback extracted from an
> > old camcorder's 1" monitor. (custom electronics could reduce the
> > steady state current to a few mA). Going to much higher DC voltages,
> > say 20-30kV much longer discharges are possible. The discharge rate
> > is controlled by the current sourcing capability of the flyback - the
> > more current that is available the faster the Cap charges to (RC) the
> > more sparks per sec - at the cost of mo!
> > !
>
> I agree that at least at the low power levels for these small coils, DC is
> easier to work with. Please explain the details of your vacuum switch
> (manufacturer, size, part number, etc.) I was thinking of using a small
> vacuum tube as a spark gap for this type of low power application. The
> theory is to find two plates spaced appropriately (on some tube) to give you
> the breakdown voltage you would like and also not be passing so much power
> thru a small area to vaporize it.
> 8-10 inch discharges from less than 1 watt!!!!!! This supports my belief
> that much longer sparks are attainable from the power levels that most
> people are running their coils at. This is why I am winding my high
> inductance series pancake coil.
Every coil has a voltage limitation beyond which its windings will
flashover unless better insulated (e.g. run in oil). I have run a
number of single layer windings up to theirs (top to bottom
flashovers) and don't really see any benefits in cramming more wire
into less and less height for air operation. I'll be interested to
hear how this goes.
Just for the record, I have tested interturn insulation using
polyesterimide coated magnet wire (0.9mm dia) and found it can stand
in excess of 10kVDC. I don't know what it can stand under hi-freq
conditions where local ionization would be important but in excess of
2kV seems realistic. The basic message is that no matter how good the
interturn insulation might be, it is generally going to be the end to
end voltage and insulation that is going to dictate what the coil can
withstand.
Comments?
Malcolm
<snip>