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Re: Flat coils & undamped waves (was Wire Length)

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

Hi Ed,
I am probably splitting hairs here, but is it more likely that the
inductance of a cylindrical coil is greater than a spiral employing
the same amount of copper, rather than Q; the ac resistance perhaps
remaining the same?

Also I think I am right in saying that a spiral coil provides less
magnetic coupling, and so in the case of TCs this provides a better
condition for free resonance (i.e. less quenching required on the
static gap)?


I can't answer the first question re "ac resistance" but the inductance would certainly be higher and hence, IF the ac resistance were the same, the Q would be higher. As for the coupling in a TC, there are optimum [magic] values and in general the higher the coupling the better the energy transfer. With low coupling there are many more cycles in the buildup of oscillations in the secondary and the power lost in circuit resistance will be migher. Both statements imply quenching at the correct time when all of the [remaining] energy has been transferred to the secondary.