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Re: DC drive
---------- Forwarded message ----------
Date: 7 Oct 1997 12:49:18 -0700
From: Dale Hall <Dale.Hall-at-trw-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: DC drive
Reply to: RE>DC drive
Larry,
This is an interesting approach. Some thoughts:
I have used low power DC excitation as a means to better control and evaluate
tesla behavior. Implemented as a low current HV variable DC supply charging
the resonant cap thru a large (charge and isolation) resistor ~1-10M ohm
which determined the charge time constant 10-100ms -at-.01uf via variable
voltage to vary cap charge current. A variable vacuum gap allowed rapid
quench. While thought about, I never pursued a Bipolar or High power scheme.
The classic case may be divided into two modes (cycles):
1.) Cap charge - usually at a rate long compared to resonance period.
Isolated from the resonant system physically by gap or by time
(too slow to initiate resonant interchange).
The Rchg=Rsec power source (NST secondary 10K-20K ohms?, etc)
for cap parallel secondary, more complex with cap series primary
as there is an inductive component with coil being shock exited.
2.) Cap discharge - Very fast-less than resonant period-at high current
shocking the resonant system into the damped ring HV discharge mode.
Fired Rgap must be very low to enable very high current exchange
with the primary resonant cap. The period of gap continuity until
it extinguishes (ionized spark is quenched, gap = open circuit)
determines the end of resonant cycle energy interchange marking
the end of output discharge and when next charge cycle may start.
Your Biolar approach uses a shock excited charge/opposite polarity discharge requiring the 2uf storage Cap to participate as a low series R and L with a hard to evaluate amount of charge remaining on the resonance caps.
To get it to work may require special attention to the gap dwell time and/or
revision of the RSG to have a discharge cycle that excludes the storage cap,
i.e. connects the resonant caps alternately to the storage cap then exclusively to the primary.
Good Luck & keep us posted ! Dale
--------------------------------------
Date: 10/6/97 10:06 PM
To: Dale Hall
From: Tesla List
---------- Forwarded message ----------
Date: Mon, 6 Oct 97 06:26:45 UT
From: Larry Robertson <LWRobertson-at-classic.msn-dot-com>
To: Tesla Builders <tesla-at-pupman-dot-com>
Subject: DC drive
Greg and all ...
The only way to view this is with a Monospaced font.
________ ________
________| | | |________ +
| Diode |___| RF | ___
| Bridge | | Filter | ___ 2uF storage cap
15 kV | | | | |
AC | | | | |
________| |___| |--------- -
|________| |________|
+ __________________
| *
| ----* * *-------- 0.05 resonance cap
- --------- | |------| |------
| ---* *--------* *------ |
| | Primary
|_______ * * *--------| 0.05 |
*-------------|------| |------
I realize this is not exactly 100% wonderfully
clear, but let me describe what I think will happen.
The stars above represent the electrodes on the RSG.
The + and - on the bottom drawing are continued from the
+ and - above.
There are 4 electrodes on the rotor - the electrodes at
0 and 180 degrees are connected togeather and insulated
from the electrodes at 90 and 270, also connected togeather.
In the position shown, the resonance caps will be charged
+ on the bottom, - on the top when the gaps fire. After
rotating 45 degrees, the resonance caps will be charged
- on top, and + on top when the gaps fire.
I am only calling them resonance caps because in each
presentation all 3 caps are in series but the big 2 uF
cap is not changing the resonance picture much,serving
as an energy reservoir to recharge the smaller caps
in the opposite polarity.
In a way this is sort of like a 2 stage Marx bank, at
least from the point of view of the primary,
Does this make any sense at all? The only downsides
I have thought of is if the resonance caps fail all of
the energy in the storage cap will dump into the short,
possibly creating some excitement.
Theorising in Morgan Hill
LR