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Re: SIDAC Spark Substitute

Original poster: "Peter Terren" <pterren1@xxxxxxxxxxxx>

Derek and Shaun
I am not sure what I can push the SIDAC's to and have not burnt them out yet although they get warm on a short run. Currently dumping 5.2kV 30nF cap (0.4j) a few times a second into 5 primary TC turns which is not enough for spark growth. I am not sure about how well they quench as well. Clearly they do a lot better with a high inductance coil such as an ignition coil. I should try this on my 18 x 48 inch coil with Fres of 38Hz. It may work better but still look proportionately small.
The di/dt is 125A/uS is enough to get to full rated current in one uS. Peak current is 130A for 10uS pulse for this small package . By comparison a CDC cap of the larger size I use (0.33uF) has a 600A peak and 1900 V dV/dt.
I think I can do better as I have been cautious so far. I need to do some CRO measurements first though and put them under oil. It is not likely to be a serious proposition for a TC (but what if they bring out a fast SIDAC 'brick'?).
I have had a Plasmasonic 1 board for a year or so, unpopulated as yet. Dan reassures me it will be worth a lot one day! I have some CM300 IGBT's rated at 600A so aim for a DRSSTC or Royer type circuit at some stage. I also have a 60kW transmitting valve for 30MHz so a 'small' VTTC is also on the wish list.
Peter (Tesla Downunder)

Original poster: Shaun Epp <scepp@xxxxxxx>
...It's a great idea in theory but unfortunatly not practical. The SIDACs wouldn't be able to handle the current which is hundreds of amps pulsed in a tesla coil primary circuit. I've never seen high current SIDAC's but I've played with ignition coil like circuits too using them.
You could look into OLTC type telsa coils(I'm not sure if they're simpler or not compared to an SSTC) or obtain a PlasmaSonic board that someone on the list isn't using and make yourself a SSTC.....
Shaun Epp

Original poster: "Derek Woodroffe" <tesla@xxxxxxxxxxxxxxx>
...I tried using a SIDAC device, to replace a spark gap, with poor results,
They have similar DI/DT times as Triacs and that is what I put my bad
performance down to. I also tried them in an OLTC type circuit with a
capacitor and DC....> I must admit to being impressed with the IC sparks though. They should work
ok in very low Frez circuits e.g cored transformers, or maybe big TC's

----- Original Message ----- : "Peter Terren" <pterren@xxxxxxxxxxxx>
This is a proof of principle coil rather than a big performer. It uses SIDAC's in place of a spark gap As set up at present it is driven by a MOT transformer with the associated 11kV diode and 0.95 uF 2KVAC cap wired as a voltage doubler to provide 5.6 KV or so. This is dumped by a SIDAC or rather 22 in series each shunted by 1 megOhm. Each SIDAC is rated to breakdown at 240V and has a 1A RMS or 20A pulse capacity. The string of 22 SIDAC's will nominally breakdown at 5280V.

Peter (Tesla Downunder)