# Re: Now, How does a coil really work??

```All what I can say is that to understand how the primary/secondary energy
transfer works I recommend the procedure I followed:

- get a good book with a decent explanation about air core resonance
transformers
"Static and dynamic electricity" by Smythe is one.

- skip the maths if hard to follow but stick to the results: in particular,
get a clear vision about the effect of different coupling coefficients, the
effect of coils tuned to the same frequency and to different resonance
frequencies.

- now the part that many people skip: when the spark gap opens, the
secondary will go on oscillating freely at its natural frequency until all
its energy is dissipated into losses.

- another part that many skip: the effect of streamers on all the above. If
a streamer is formed, it will suck the secondary energy and will dump
whatever is going on (energy transfer if the gap is still closed, secondary
free oscillation if the gap is already open).

- now you have reached knowledge at the single bang level: what is the
effect of multiple consecutive bangs (i.e. a rotary gap)? I have no answers
(yet) about their effect to streamer length, but at least they have no
effect on the secondary voltage until the bang rate is so high that you are
able to catch the tail of the freely oscillating secondary and (again, with
resonant charging) buildup a higher voltage.
On my TC this would require a pulse rate of 1250 Hz: too fast to be done!
And remember: whenever you have a streamer the voltage on the secondary
will die down even faster (i,e, higher pulse rate required to buildup
voltage from pulse to pulse).

- pulse repetition, thus, affects just streamer length and NOT secondary
voltage (at usual pulse rates, at least).

```