Re: Interference-SSTC

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Fucian-at-aol-dot-com>

In a message dated 2/23/02 2:14:12 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

<< Ok you could. But efficiency will go down a lot. Shorter streamers even at
 high power levels.
 
 Say, you half the frequency but still use the same input voltage, and
 want the same input power draw. Then the new series resistor to add has a
 resistance equal to the impedance of the TC pri-sec system at your new
 drive frequency (this could be some ten Ohms or so). 
 
 That it turn means that half the power goes to the streamers, half to the
 resistor. T.ex. if your SSTC would draw 400W then you will get 200W into
 the TC and 200W into the resistor. 
 
 The 200W into the resistor are "lost" power - heats up. 
 I'm sure you want streamers, and not a finnish sauna... :o)
 
 If you go to even less than half the original freq, even more power will
 be dissipated in the resistor, and even less in the TC.
 
 Without the resistor and just double the primary turns (to get the _same_
 current as in the above scenario with the resistor) all power will be
 applied to the secondary coil. So 400W will go as 400W into the TC, and is
 not split over resistor and TC.
 
 
 cheers,
 
  - Jan
  >>
Ok i think i will add more turns instead of a power resistor.:-)

Its just that this MOSFET gets so hot so quick.Less than 3seconds 
sometimes.They are IRF840s.The heatsink is of good size.I cant figure it 
out.And to make matters worse, the 555 circuit has now died.I replaced the 
555 and no help.I will check the transistor buffer next.

Anyway, im going to move to the new dual mosfet driver circuit that I posted 
a few weeks ago.As soon as i can find a 1mH choke.(No inductance meter).

Matt