[Prev][Next][Index][Thread]
Building advice -Reply
----------
From: Antonio C. M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent: Tuesday, March 17, 1998 11:38 PM
To: Tesla List
Subject: Re: Building advice -Reply
Dale McLane wrote:
> 3) For the uninitiated i.e. myself, and others who may be in "lurk mode", what is the function of a
> "Tank Circuit" ??
A "tank circuit" is a parallel or series connection of an inductor and a capacitor. A Tesla coil
is essentially two parallel tanks connected through the mutual inductance of the inductors. The
capacitor on the secondary side is a distributed capacitor formed by the parallel connection of
the equivalent self-capacitance of the secondary coil (that can be considered also as a transmission
line effect) and the distributed capacitance of the top terminal, if present.
In a parallel tank circuit, if the capacitor is charged and connected to the inductor, the result
is an oscillation at the frequency 1/(2*pi*sqrt(L*C)). Losses in the circuit cause the oscillation
to decay exponentially with time, and a slight change in the frequency.
In a Tesla coil, the oscillation on the primary, low-impedance, tank induces another oscillation
in the secondary, high-impedance tank. If the system is correctly tuned (both tanks at the same
frequency), periodically all the energy in the circuit (the initial energy in the primary capacitor
minus losses) appears in the secondary capacitor, charging it to very high voltage.
> 4) It it possible to build a "tuneable variable frequency TC" that would work on certain frequencies, I
> realize that there probably harmonics all over the place, but........?
With no breakout the operation is essentially at a single frequency, the resonance frequency of
the two tanks (actually two closely spaced frequencies while the primary is active and a single one
after the spark gap opens). A variable TC would require simultaneous tuning of the primary and secondary
circuits. Practical problems on how to implement this I leave to more experienced "coilers".
Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq