Re: drsstc questions

["Tesla list" <tesla@xxxxxxxxxx>]

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!!

Cheers,

        Terry


> Mike