# Voltage/Length (fwd)

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From:  John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent:  Friday, January 23, 1998 8:48 PM
To:  Tesla List
Subject:  Re: Voltage/Length (fwd)

Greg -

There is no question that the energy in the secondary circuit is less than
the energy in the primary circuit as I indicated. However, you did not
address the issue of POWER in the secondary circuit. This power is much
greater than in the primary circuit. This means that the energy equation you
used must be modified to reflect power not energy in the secondary circuit.
The sec voltage is not RMS as in the pri circuit.

The TC can magnify power which makes it unique in the electrical world as
no other electrical device can do this magic. This confounds many engineers,
scientists, etc. who are not familiar with TC operation. This makes TC
design a challenge to produce a good coil.

For your example  100 pf  3 MV  240 bks.
The watts (power) in the secondary = 450 x 240 =108 000 Inst watts
The efficiency of a coil this size is about 12 percent overall.
This requires the equivalent of 900 000 Inst watts in the primary but at
RMS conditions.

Primary RMS watts for one second = Inst sec watts / TC power gain

The JHCTES program shows about 45 000 RMS watts for 3 MV and a 20 ft spark.
The spark is a controlled spark and not the maximum.
However, there are many other possibilities for wattage design.

TC Power gain = Inst sec watts / Pri RMS watts = 900 000 / 45 000 = 20

The TC power gain for the Tuve et al 5MV coil of 1930 was 567, at one
pulse per second. Note that number of breaks and time are important. The
calculations are shown in the Tesla Coil Construction Guide. However, this
coil was in oil and the losses were much less than when a coil is in air.
The TC power gain of a coil in air would be much less. The gain varies with
the geometry of the coils and can only be determined empirically.

By empirically I mean by collecting data from coilers who have built good
coils and tested them properly. I collected this data from my own coils and
coils of other coilers several years ago to develop the JHCTES TC computer
program. This program is based on both theoretical equations and empirical
data. I agree this program can be improved with more data from building and
testing new coils .

Note that the equations using the capacitances, inductances, Q factors,
etc, will not give real world information unless additional empirical
information is available as I state in the Tesla Coil Design Manual.

Thank you Greg for giving me the opportunity to mention my products.

John Couture

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At 11:31 PM 1/22/98 +0000, you wrote:
>
>----------
>From:  Greg Leyh [SMTP:lod-at-pacbell-dot-net]
>Sent:  Thursday, January 22, 1998 6:33 AM
>To:  Tesla List
>Subject:  Re: Voltage/Length (fwd)
>
>John H. Couture wrote:
>
>
>>   Greg -
>>
>>   The equation you used to find the TC secondary circuit voltage
>>             Joules = .5 x C x V^2
>> can be used to find the joules, capacitance, or voltage in the TC primary
>> circuit. These joules or energy will appear in the secondary circuit with a
>> certain efficiency. However, this joule equation cannot be used to find the
>> TC secondary voltage. In the pri circuit the voltage is RMS, 60 Hz, but in
>> the secondary the voltage is of an instantaneous dampened wave type. The
>> dampened wave can be seen on an oscilloscope and the peak amplitude
>> estimated. However, this is not of much use because this is not the voltage
>> to which the secondary terminal is charged.
>[snip]
>
>
>Conservation Of Energy is _completely_ independent of
>waveforms, frequencies, and the like, and only concerns
>itself with the instantaneous energies in the reactive
>components of the circuit.
>
>In a standard pulsed Tesla Coil, the primary capacitor
>provides all of the circuit energy when the gap fires,
>as the secondary has completely rung down by this point.
>The total energy available to the circuit at this instant
>is given by  Epri = .5 x Cpri x Vpri^2, where
>
>Epri -- energy in primary capacitor
>Cpri -- capacitance of primary capacitor
>Vpri -- voltage on the primary capacitor
>
>If we hold that the Conservation of Energy is valid, then
>at no instant can the energy in the secondary be greater
>than the primary energy, regardless of how it got there.
>
>Even if the coil were 100% efficient, the _maximum_
>possible output voltage can be no greater than
>Esec = .5 x Csec x Vsec^2,    where Esec = Epri.
>
>
>These equations can be boiled down to give an absolute
>maximum limit for the output voltage:
>Vsec(max) = Vpri x SQRT(Cpri/Csec).
>
>Any coil system that can generate more output voltage
>than prescribed by this equation has somehow circumvented
>the Conservation Of Energy, and should by all rights be
>promoted to the realm of the greater-than-unity machines
>on the usa-tesla list.
>
>
>-GL

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