Re: Early versions of Tesla's coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <teslalist-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
 >
 > Original poster: "John H. Couture by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
 >
 > Ed -
 >
 > Why would there be two energy storage sources, one as the buzzer coil
 > (contacts closed) and one as the capacitor (contact opened)?  That would
 > only increase the losses. The energy in the buzzer coil cannot be used twice
 > in the TC primary as this would imply over unity energy. I would be
 > interested in reading Curtis's description of this operation.
 >
 >   In fact I believe this device would work without the capacitor but not as
 > well. Only the energy from the buzzer coil is needed to energize the TC
 > primary coil. I believe the capacitor only protects the contacts and they
 > last longer.
 >
 > John Couture

	The law of conservation of energy is not defeated and no "over unity"
is involved.  Not permitted on this list anyway!  The actual voltage
across the capacitor will be the final current in the buzzer inductor
times the square root of L/C, where L is the buzzer inductance and C is
primary capacitor for the TC.  I haven't made any measurements on the
coil I have, but make this guess:

	Suppose the inductance of the buzzer is 0.1 henry (it's probably a lot
more) and the primary capacitor is 5 nf.  If the current flowing in the
buzzer just before the contacts open is 0.5 amp (another wild guess) The
resultant voltage across the capacitor will be about 2200 volts.  If the
contacts close again at the right time (Antonio can help on this) that
capacitor voltage will be discharged through the TC primary.  About the
same as charging the capacitor from a 2200 volt (peak) transformer.
Note that there are two separate resonant circuits involved, both
involving the same capacitor.  The first and lowest resonant frequency
is that of the buzzer inductor and the primary capacitor, while the
second is that of the primary capacitor and the TC primary inductor.

	I haven't made any waveform measurements because I'm very reluctant to
have the thing running near my scope.  Maybe Terry could make the
appropriate measurements on one of his (he certainly is adequately
equipped) and report the results.

Ed