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Re: drsstc questions

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Mike,

At 10:32 PM 3/27/2005, you wrote:
I was thinking of jumping on the bandwagon and i was wondering several things:

1. Could these things be ran w/o the big electrolytic caps if it was ran from a 720v Li ion battery pack (5A max continuous current draw)?

The peak power of say Li-poly is very high... You would have to find the spec limits and stay inside that. I think that is possible with some buffer caps and maybe inductors to limit the peak current to the batteries. You would need the equipment to check all that. Note that Li-poly power pack explosions are pretty dramatic and have fried cars and stuff!!

Or are they more than just for filtering? I figured if I'm gonna do this might as well make it portable than can be ran anywhere since it'll be alot lighter than 100 lbs of nst's and a variac. I don't plan to go over around 2kW.

DRSSTCs don't have NSTs, variacs, or spark gaps ;-))) No "big iron"... My whole thing (coil / driver + all the wires and junk) weighs 40 pounds... Even Li-poly batteries weigh more than an AC plug ;-)) - I use li-poly for all my robot stuff,. so I know all about them too *:-))

2. Has anyone figured out the most efficient on/off times/bps for a given power to get the longest spark?

120BPS seems to be a winner!! About 350uS PW... But all that is trivial to change as you please.

I figured if I got a half bridge of those Powerex 1200v 600A bricks I could run them at 5% duty w/o blowing them up with only 2kW. With that in mind I came up with a back-of -the-envelope table from 10us on/190us off/5000 bps on down to 1ms on/19ms off/50bps at max power. Obviously the extremes of that won't work since the spark will die before the next pulse or the caps will from high rms current. I figured once I found the optimal pulse width I could vary the power by varying the bps/off time as long as I don't exceed the 5%. Sounds like an experiment for Terry :).

Just make it all "variable". The ranges you mention are "just a resistor value"... Think about input power and design it to pull so many amps off the AC line or your batteries. If you have say a kW, you have enough ;-))

3. Did an ebay search of the above bricks and didn't find any. How often are those there?

Gosh!! Are they "out"!! I gave all mine to Steve!!