[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] SISG success

Hi Herwig,

Happy here to know that your coil is working so well!!

SISGs "rock"!!!

I sort of lost interest in coils after the SISG... I know it will take others "years" to catch up :D Sort of like landing on Mars while most are trying to get off the planet :)

But there are folks like you that are the forerunners into the future!!

Best Regards,


Herwig Roscher wrote:
Hi coilers,

Yesterday I have maxed out my copy of Terrys wonderful Piranha system:
(c) = calculated	(m) = measured		(r) = rated

No_load_output of MOT = 3367 V peak (m), MOT gets warm only a little bit.

Firing voltage of 2 boards SISG4 set to 6900 V (r), IGBTs remain stone cold even without cooling fan and even at max current.

Primary coil: inverted cone type, 25 deg (laying around), minimum horizontal distance between primary and secondary coil is 1.26"
Lp = 13.7 µH (c)
Cp = 162.5 nF +- 5% (r)

Secondary coil: 6.3" by 22.8", 1360 turns, wire about AWG 27, lowermost turns of primary and secondary coil are in the same plane, F res = 106.5 kHz (m) when sitting inside the primary coil
Ls = 73,5 mH (c)
Cs = 10.6 pF (c)

Toroid 4.33" by 19.3" (outer dimensions) dryer duct (laying around), covered with aluminum foil, vertical distance between toroid and uppermost turn of secondary coil is 3.75"
C top = 20.7 pF (c)

I have increased Cp step by step , carefully retuning the system after each step of course. Finally I reached a strike distance of 35.5". Although I am very satisfied with this good running system, I would like to come a bit closer to the magic 42", Terry has reported: The toroid is smooth (not so smooth as a spun one) and maybe a little too small, but as it generates *one* streamer mostly, I assume it to be close to optimal.

The streamer length *decreased* when I lowered the firing voltage of the SISG4s to 6600 V = increasing BPS. As the SISG4s continued regular firing when I increased Cp, the MOT seems to be able to charge the 162.5 nF Cp up to full voltage.

As the calculated(!) peak current is close to 750 A already I did not dare to increase Cp further more. Cp consists of several groups of capacitors which are connected with thick but long wires. Some of the capacitors are removed from a Klystron-power supply and get warm a little bit. Could ESR and wire resistance be responsible for a lower primary peak current, lowering the strike distance? Are there any other measures I could try in order to increase the strike distance a little bit?

While copying Terrys Piranha system I have learned a lot and running it is great pleasure. Thank you for inventing it, Terry!

Bye		Herwig

Greed is the root of all evil !

Tesla mailing list

Tesla mailing list