Re: MOT level shifter

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

Original poster: "Herwig Roscher by way of Terry Fritz <twftesla-at-qwest-dot-net>" <herwig.roscher-at-gmx.de>


Gregory Hunter wrote:
 
> MOTs *ARE* current limited. The MOT shunts are not as 
effective as NST shunts, but they do work.

Greg,

I only wanted to discriminate between xformers needing an 
additional ballast and those with a built-in one.

> Using 4 level-shifter MOT caps in series instead of only two 
halved the capacitance and cut the power down to about 1750VA.
- Interesting figures. Way to go.

> I couldn't figure out how to optimize a tank cap for such a weird 
supply either, so I gave up and tried 47nF. 
- So we are facing the same problem  ;-)

That's the dilemma:
>This was grossly undersize, and I'm sure the stiff 12kv pulses 
forced it to fire in "burst mode", with a cluster of bangs each time a
pulse came out of the level shifter.

> I think it wise to keep the tank cap smallish
> to avoid loading down the level-shifter cap.

So, how to design the cap?

>  Marco Denicolai ran a twin MOT/level shifter on his first coil, and 
I think he used a .5uF tank cap with good results.
- That's a lot of capacity and expensive too.

> I don't think the reso cap, LTR cap, or any of the other familiar NST stuff
> is even relevant with the MOT/level shifter supply.
- This I would like to find out.

Regards,

Herwig