Re: Another MMC cap candidate (UK)

On Thu, 24 Jun 1999, Tesla List wrote:

> Original Poster: Alan Sharp <AlanSharp-at-compuserve-dot-com> 
> >I plan to buy another 130 of these 47nF/1500V units from RS.
> >I can't find a cheaper supply.  However there is a significant
> >reduction in unit cost for a bulk order, if any UK people are
> >interested ?
> >100 off -at- 0.348   500 off -at- 0.32   1000 off -at- 0.254,
> I intend to buy 200 of these caps soon.
> The differnce between 100+ and 500+ wouldn't pay the postage costs.

 They may be able to deliver some quantity to RS Trade counter Gateshead
and the rest to Corby ??

> >When I built my MMC I simply stacked the capacitors in an
> >8 by 8 block shape, (kind of like a hexagon pattern.)
> If it works I can't argue but I'ld worry about heat build up and voltage
> insulation.
> The total length of the leads will be no longer on a pcb - more induction
> though.
> What coil are you running off this - transformer voltage, frequency,
> spark length?
> Alan

The current transformer voltage is 6kv rms,  but the rotary firing and
resonant charging bring the peak cap voltage to about 12kv.  The DC rating
of the cap is 12kv so its right on the edge.  The break rate is 200BPS
sync,  so it is high compared to 100BPS sync but low compared to static
gaps.  It will be interesting to see if there is any heat build up after
long runs.

I think the res frequency is more important in CW applications like tube
coils.  It might be less important in pulsed duty ?

Current wall power is about 600VA,  and spark length is around 28".

I am building another 3 of these MMC units to run up to 24kv. Power will
be around 2kW.

					- Richie.

					- In sunny Newcastle.