Re: curious TC questions on Freq. limits

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jan Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>

Hi,

On Tue, 8 Oct 2002, Tesla list wrote:
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<CoolCorals-at-aol-dot-com>
> Hello, I have been curious about a few things with a tesla coil.
>      First:  I have read some of tesla's patents and articles.  It seems
> Tesla talks of a TC running in the MHZ to 100MHZ ranges, has anyone done
> this?  Is it possible?

There's a project paper around in which a group made a 5 MHz TC.
Naturally, at 5MHz the coil size is tiny, it is prone to detuning
(just thinking about driving it with a 5 MHz signal generator), and input
power has to be quite small to prevent this small TC from burning up.
Energy "losses" are high.

>      Second:  It seems that tesla often used DC for the input to his TC's,
> and the rotated a "contactor" to determine input frequency.  How does raising
> or lowering the input frequency from 60 hz change the resonant frequency?

Doesn't affect it at all. The resonant frequency/ies of neither the tank
nor the TC secondary depend on what exactly you use to feed the TC.

But, changing the contactor speed (rotational spark gap?), you will change
the energy per bang. That depends on the supply VA rating and frequency,
and how you charge, and what kind of supply it is (DC, AC, 3-phase).

Someone else on the list will probably know better what Tesla tried to do
with DC and the rotated contactor... :-) My guess is that he was just
determining the optimum time (i.e. bps) to fire the gap/close the
contactor, which is after the tank cap has been fully charged up to DC
supply voltage. Something like T_charging >= Z_out_supply * C_tank, or so


 - Jan

--
*************************************************
 high voltage at http://www.hut.fi/~jwagner/tesla
 Jan OH2GHR