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Terry's DRSSTC - 6000 BPS >:o)

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi All,

By simply changing the controller program (took all day...), I can now run at over 6000 BPS >:D Hey! it's just electronics ;o))

With the list down today (odd "power surge" Chip says ;-))) I was trading E-mails with Steve Ward so I will past them together here...


How does the coil run at 5000bps? And have you cranked it up yet? :-)))

It takes "very little" T1 to get long streamers!!! I think they are right about a lot of energy / time, but it seems to make longer streamers than expected to me. Have not studied that yet since just working to get the BPS rate up... The thing does not have time to ring down so the effect where the streamers get big and small periodically with small changes in BPS is really pronounced. It sounds like a hammer hitting a steel spike. Sort of a "Tink, Tink, Tink,..." sound. T1 is only about 30uS but it still hits a foot with 25 Reps / T4. The sparks look like they would kill!!! I stopped to redo the program and then got into all this timing stuff. I use the new timing stuff now and it should be vastly better for programming!!


Going to reprogram and verify the controller now... I suppose I should worry about the stress on the IGBTs, but indoors at 30uS for T1 should not be a problem.


Hi Again Steve,

Now I can go just over 6000 BPS >:))) The microcontroller needs 125uS to go from line (on) to line (off) which is the limit. The next controller might need the "Rabbit" type that rips at 40MHz and has 500K of memories (it can play wave audio files ;-)) But the little stamp is doing very well!!

It seems that each bang just "adds" to the next. I don't mean like a streamer follows the path from the last bang. It is like the T1 time is just stretched out. The T2 times seem to get lost and the streamer builds like it was just one long T1 time. It definitely has a strong long and sort streamer affect with just a small change in BPS still. I had to keep lowering the T1 time to keep the streamers at a sane length!!

The BPS rate is higher than I apparently can hear. It just started to turn into sort of a "puff" sound at near 6000.

The streamers seemed to get sort of a sward like appearance to them like a tube coil has. But unlike a tube coil, these streamers have a lot more power behind them!! (or they would if I would crank it up ;-)) I worry about where the IGBT load is at. The current should be low and the heating should be low... I don't have a scope on it yet since the antenna are not at a safe distance now if something were to go wrong (I can easily fix that...). But I wonder what the fast thermal heat on the IGBT is like during a burst. It might be just fine, but I am not sure...

Super high BPS operation seems super cool! We think of the energy in a single bang vs streamer length. Now maybe we can think of streamer length in 25 bangs all adding "power"!! The streamer length at 6000 BPS (25 repetitions) is well over a foot. If I turn down just the BPS leaving T1 the same, the length is like 1 inch at 500 BPS!! SQRT(25) is 5 so the length seems greater than expected from just adding repetitions!!

The little microcontroller's timing is just about "perfect". I wonder if like a 555 timer setup would be good enough not to drift or if drift is even critical? I suppose I could hard program "jitter" into the thing....

Many Wild and Wonderful things at high BPS!! I suppose maybe we should think of a new Tesla coil "class of operation" now since things are dramatically different up there....

Well the snow has stopped and hopefully it will dry fast... I will retool to get the scopes in there... The 6000 BPS is not bad but, the 3000 really grinds the nerves!! Probably good to shoot for supersonic BPS rates to save one's mind!!


Hi Again Steve,

I took some scope pictures. This is my DRSSTC running at "only" 2940 BPS ;-) There are all kinds of harmonics up there but this one was most interesting:



The first three pulses die down since the previous pulse ringdown is out of sync with it. But on the fourth pulse they sync up again and a nice power burst is produced. One can hear the different tones from these harmonics.

Here is another odd one:


The best sparks are when they all seem to stay in sync through the burst!!


The difference in spark length between in sync and out of sync is very dramatic!! It is almost like the out of sync situation "poison's" the streamers!