Re: High Power Solid State Tesla Coil - Successful Test

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

Original poster: "Darren Freeman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <free0076-at-flinders.edu.au>

Dan,

At 02:57 PM 05/07/2002, you wrote:
>Original poster: "Daniel McCauley by way of Terry Fritz 
><twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>
>
>Just finished all my "resisitive load" tests on my new high power solid
>state tesla coil driver and decided to go with a quick first time test with
>the primary connected.

I'm also working on a solid state driver for my coil.. It's been a very 
long time in the works due to limited funds / equipment.

I don't tend to post on the pupman list coz there's so friggin' many posts 
each day =)

>Darn, didn't have enough wire, but managed to get 10 turns of 10 AWG wire on
>the primary.

Old 50 ohm coax seems to work well, using the braid as the conductor.

>Powered up the unit with 120VAC, half-rectified into the unit and nothing!
>Gotta tune it.  Turned the frequency adjust pot a
>few turns and then the thing came to life.  Really loud and nice white arcs
>approximately 15 inches long.  Not bad seeing the thing isn't tuned too well

You don't have any idea how LUCKY you are =) I have blown a pair of MOSFETs 
on each test for about 10 times.

Sometimes on stupidly low inputs like 50 VAC.

Turns out to be a poor choice of power supply routing, ringing up across 
the MOSFET bridges. I killed 450 V MOSFETs from 30 V once!!

Anyway, just wanted to let you know how lucky you are to have 15 inch arcs 
on first go - I've had maximum 10 inch sparks before BANG!

BTW, you start to get twitchy after having MOSFETs explode like 
firecrackers 100% of the time - you never know how far up the variac to go =)

I think its fixed now tho, gotta replace 4 MOSFETs and give it another whirl =)

>and haven't really played with the primary coupling or # turns etc...  Ran
>for 15 minutes (man lots of ozone!!!), and the FETs are actually COOL to the
>touch!!!!  Excellent.

Yeah that's another tricky thing to achieve when using homemade pulse 
transformers to drive the gates... On high supply currents anyway..

>Now, put up my 120-240VAC transformer in the circuit.  Now i'm running
>240VAC, half-rectified into the full bridge circuit.
>WOW!!!!!  The thing comes up and is super loud for a solid state coil.  Fat,
>white arcs with a low frequency cackling hum almost 30 INCHES LONG!!!!!!

Once again, lucky so-and-so =)

>Look out conventional coils.  Ran again for 15 minutes (boy its getting hard
>to breath down here!) and the heatsinks are only slightly warm.  Well,
>tomorrow, we'll put the variac in the circuit and work up to 480 volts
>input, half-rectified.   Wish me luck.

I think you don't need it =) But good luck =)

>The most recent pictures and specifications of this new coil are at the
>following link:
>
>http://www.spacecatlighting-dot-com/teslacoil2.htm

I must congratulate you on the board - it's very pretty =) Lots of chips, I 
suppose you put a lot of thought into it, so no wonder it worked =)

I have decided that breadboarding the logic of a coil driver is OK for 24V 
tests but not a good idea when running mains input =) The coil couples very 
well to the breadboard, inducing faults that shouldn't be there... But that 
was expected anyway...

>Dan

Well.. I'm impressed and curious. If you want to talk more off list I'd be 
keen..

BTW if anybody replies then please CC to my address as otherwise I probably 
won't notice it.

Have fun,
Darren Freeman