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Re: Solid-state tesla circuit

Jeff wrote:

>Has anyone built either of these circuits? I would also love to hear from
>anyone who has built any type of solid-state tesla coil and can point me in
>the right directions. Thanks in advance!

I looked at the circuits in Bylunds book - if you can get the PSU that he used
and modify it then you might want to go for it.

Otherwise use MOSFET's - IRF740 400v, 20A 100W fast switching are ideal.
Much faster switching, and less heat than bipolars.

Look at the circuits for switching power supplies - especialy push - pull
and bridge designs. Most solid state designs are:

switching psu driving the primary of the output transformer
one end of the secondary to ground, other end to base of magnifier coil.

Download Rob's circuit: Driver.gif, driver.doc from the ftp site.

Rob and I both ended up with the uc3825 pwm chip - get the data sheet.
Also get sheets for lm3524 and the 3525. 

Mosfet driver chips: tc4422cpa, 4427, 4429

Another option the HIP2500IP (harris), and see the HIP5500IP

international rectifiers HEXFET data book includes useful papers.

My present design is push / pull 
uc3825 driving a pair of 4422 buffers to 3 * irf740 on each side.
Current limiting monitored across a 0.05 ohm resistor -
this creates weird feedbacks - I work around it but its something I must
sort out in the Mark 2.
driver is switched on off at about 60 Hz by a 555. (needs refined)

The outputs to 2 identical // wound primaries on a 2.5" square ferrocube
transformer, 15:1 ratio.

5 gallon polythene bucket - meant for home brewing beer.
covered with 0.4mm diameter wire (about 1000 turns 13" diameter)

At about 3A (140V - 420W) I can draw a 14" white arc to a grounded wire
from the toriod, pushing the power up to 5, 6A makes the arc brighter.
It will also light up an 8' neon tube about 5' away.

Mark Barton built a 10kw coil he called Big Fet. It produced a 3' sheet of
electrical flame:)  It was a 400v full bridge driving a large primary - the
secondary
was oil drum size - of course it blew up.

Malcolm wrote:

>  I also realized that higher break rates rather than higher bang 
>energy will simply mean losing less more often. I say go for it with 
>the MOSFETs Alan! In fact, I would expect expect your efficiency to
>scale much better as you up power.
     
I'm building a 180v, 1200W PSU for my next effort at the moment.
I'm also going to use 6 FET's on each side, bigger output transformer,
higher ratio and try for more intense but shorter bursts. I'll be putting
in at least double the voltage at the base of the magnifier. Will it make
double the arc length or just some very expensive smoke - 
thats the question :)

Have fun,

Alan Sharp UK