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RE>Multi-layered Sec + batt
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From: Dale Hall [SMTP:Dale.Hall-at-trw-dot-com]
Sent: Tuesday, March 24, 1998 5:11 PM
To: Tesla List
Subject: RE>Multi-layered Sec + batt
RE>Multi-layered Sec + batt
Original (below) reformatted/resent 3/24 w/ CR's for Malcom (sorry) & List
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Date: 3/24/98 7:21 AM
To: Dale Hall
From: Tesla List
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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
RE>Multi-layered Sec + batt desktop TC
rejected(?): SMTP:aerpel-at-op-dot-net: 550 <SMTP:aerpel-at-op-dot-net>. User unknown (Alfred?)
Reformatted/resent 3/24 w/ CR's for Malcom (sorry) & List
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 powered by 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 SPARK rate is
controlled by the current sourcing capability of the flyback - the more current that is
available the faster the Cap charges (or RC) so more sparks per sec - at the cost
of more input (battery) power required. This mode allows analysis on a storage
scope of each spark relative to the gap firing that caused it. (Would like to be able
to compare still photo of spark to its scope trace printout but no photo capability yet -
might lead to figuring out what is mechanism of those bright spots that occur mid arc).
Many on the list have been looking for a way to measure jagged discharge lengths.
Using this controlled approach I've been able to do that electronically; i.e. longer
path sparks show up as longer time periods. On the above coil last evening using a 7"
pointed Sec to Gnd control, gap fire to spark time varied 9 to 12 us for subsequent
sparks at Pri energy = .1uF*5kV^2/2=1.25J appearing to correlate with varied path
lengths of individual spark lengths - eye balled spark then studied resultant scope traces.
So. Calif LA area: TRW radio/electronics Swap meet is Sat 3/28 7-11am Redondo Beach.
See you there ?
(boy, this IS fun!) Dale
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From: Alfred C. Erpel [SMTP:aerpel-at-op-dot-net]
Sent: Sunday, March 22, 1998 7:03 PM
To: Tesla List
Subject: RE: Multi-layered Secondary
.... snip
It is approximately 1.5 OD x 5.7 high. Anticipated inductance is
approximately .1 Henry. 3.5 ohms resistance. Awesome Q. Something unknown
(to me) is how much distributive capacitance this type of coil will display.
At 50 picofarads, total capacitance (with top load), its frequency will be
71 kHz. This works out to a theoretical Q of greater than 12,000! (2 x pi
x freq x inductance / resistance )
I am planning for this coil to be run on my desktop, and hopefully battery
powered. And I still have not nailed the exact configuration of the power
supply feeding the primary. Right now I am trying to adapt the charging
circuit from a disposable flash camera as a power supply for this coil; I
have wound a small transformer and built a small spark gap to kick the 300
volts DC up to 9000 volts but I will probably need help on this (just tried
it this weekend with unclear results). I will post more on my small coil
as it develops.
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Date: 3/22/98 10:56 PM
To: Dale Hall
From: Tesla List