Re: familiair with rumkorff inductors? (fwd)

From: 	Antonio Carlos M. de Queiroz[SMTP:acmq-at-compuland-dot-com.br]
Sent: 	Tuesday, December 23, 1997 9:40 PM
To: 	Tesla List
Subject: 	Re: familiair with rumkorff inductors? (fwd)

Tesla List wrote:

> What is the difference between Rhumkoff coils and car ign. coil, except that
> the Rhumkoff coils oscillate on their own caused by the core magnetism and a
> relay-like trigger?

There is no fundamental difference. In any of these, the primary is connected
to a low-impedance voltage source for some time, and then the contact is
suddenly opened. The interruption of the current in the primary inductor
causes a high-voltage pulse to appear at the primary winding, and a much
higher-voltage pulse at the secondary winding, that has many more turns.
A good part of the energy accumulated in the primary inductance can be
transferred to the secondary circuit, producing sparks in a car ignition
coil. There is no resonant phenomena involved in the operation.
An induction coil can be used to power a Tesla coil, but today it really
appears more practical to use a high-voltage transformer, as an induction
coil requires a relatively low-voltage, high-current, DC power supply
(as a battery). 
A classical Ruhmkorff coil would also produce much more voltage than is
normally used in transformer-based sources, requiring a smaller capacitor
(the insulation of the capacitor can be a problem, but not so serious) and
a wider spark gap. The turns ratio of the Tesla transformer would also
be probably smaller, with more inductance in the primary circuit than
the usual, to keep a reasonable resonant frequency in the primary
circuit, or less inductance in the secondary circuit, otherwise it can
be impossible to make it resonate at sufficiently high frequency with
its own parasitic capacitance.

Antonio Carlos M. de Queiroz