New Type of SGTC?
Reaching, Thu Oct 05 2006, 10:31AMhello, i made a few thoughts about sgtcs and i had a idea. why not combine a marx generator and a sgtc?
i thought about rectifying a 6kV 120mA transformer to charge a 2 stage marx bank up to 8kV . each stage consists of 5x wima mkp10 0,22 1600v, to get a capacitance of 44nF.. when the marx stage is charged the first spark gap triggers and both stages are in series for 22nF 16kV. what would happen if you connect a primary coil of an sgtc to the marx generator.when the primary is in resonance with the 22nF 16kV cap matching the resonant frequency of the secondary coil, very long bright sparks could be possible, okay only pulsed with 1-2bps or less but is it worth the effort? 22nF 16kV are 2,8 Joule bang energy and you can add more and more stages to get more voltage and energy... just a thought but would it work?
Re: New Type of SGTC?
vasil, Thu Oct 05 2006, 11:55AM
Greg Hunter did it.
http://hot-streamer.com/greg/marx.htm
I thought to this as a simple way to rise the voltage in a double MOT SGTC....never done though...
vasil, Thu Oct 05 2006, 11:55AM
Greg Hunter did it.
http://hot-streamer.com/greg/marx.htm
I thought to this as a simple way to rise the voltage in a double MOT SGTC....never done though...
Re: New Type of SGTC?
Reaching, Thu Oct 05 2006, 04:03PM
mhh, nice, are there any pics of the setup or pictures of the discharges? my thought was to rectify the output of the hv transformer to charge a big amount of caps and stages to get a very high voltage pulse,that should give plenty of power for a short time without having a huuge hv transformer..
but its a good idea to use the maximum capacitance the transformer can charge in a halfwave to charge the marx stages,..
and ahhm, what would happen if you use more marx stages to get say 50kV and not only 12 kv or so. a 50kv transformer is hard to get and i think nobody used one in a sgtc before with such a high voltage. so what would happen if you discharge a 50kv 20nF cap into a teslacoil circuit at resonance?
Reaching, Thu Oct 05 2006, 04:03PM
mhh, nice, are there any pics of the setup or pictures of the discharges? my thought was to rectify the output of the hv transformer to charge a big amount of caps and stages to get a very high voltage pulse,that should give plenty of power for a short time without having a huuge hv transformer..
but its a good idea to use the maximum capacitance the transformer can charge in a halfwave to charge the marx stages,..
and ahhm, what would happen if you use more marx stages to get say 50kV and not only 12 kv or so. a 50kv transformer is hard to get and i think nobody used one in a sgtc before with such a high voltage. so what would happen if you discharge a 50kv 20nF cap into a teslacoil circuit at resonance?
Re: New Type of SGTC?
Marko, Thu Oct 05 2006, 05:06PM
Problem is, that when using marx you again need to make a gap that will quench well at low voltages.
Rotary gap may help as well as turning marx inductors into charging reactors, etc.
Marko, Thu Oct 05 2006, 05:06PM
Problem is, that when using marx you again need to make a gap that will quench well at low voltages.
Rotary gap may help as well as turning marx inductors into charging reactors, etc.
Re: New Type of SGTC?
HV Enthusiast, Thu Oct 05 2006, 05:18PM
Keep in mind that the long discharges from a Tesla coil are the result of continually arcing (at high frequency >60Hz for example) through previously ionized spark channels.
If you run the system this way, you just aren't going to take advantage of this action. Also, voltage is not the only parameter in creating big arcs with a Tesla coil. Current is another one, and with a marx you just won't get the large energy transfer unless you use very big caps.
I personally don't see any advantage to this.
HV Enthusiast, Thu Oct 05 2006, 05:18PM
Keep in mind that the long discharges from a Tesla coil are the result of continually arcing (at high frequency >60Hz for example) through previously ionized spark channels.
If you run the system this way, you just aren't going to take advantage of this action. Also, voltage is not the only parameter in creating big arcs with a Tesla coil. Current is another one, and with a marx you just won't get the large energy transfer unless you use very big caps.
I personally don't see any advantage to this.
Re: New Type of SGTC?
Reaching, Thu Oct 05 2006, 05:45PM
yeah i know, but whats about a drsstc in one shot mode, it does exactly the same,a long arc with the same lenght as you would usually get. so why not using a great amount of caps to get a high bang energy. the pulse would be really short i know but several yS are enough to build up a spark and let the secondary ring a few times like in a drsstc. i see no real advantage here for myself but why always so theoretical, lets try it out and see what happens.and a well build marx generator with good caps can have a high current rating, you get a short high voltage high current pulse for around 100ys or so, that can ring up a secondary coil with 100khz 10 times, more than enough to ionize the air and build up a spark.
the only problem i see is the resistance of the spark gaps, this will reduce the maximum current flow
Reaching, Thu Oct 05 2006, 05:45PM
yeah i know, but whats about a drsstc in one shot mode, it does exactly the same,a long arc with the same lenght as you would usually get. so why not using a great amount of caps to get a high bang energy. the pulse would be really short i know but several yS are enough to build up a spark and let the secondary ring a few times like in a drsstc. i see no real advantage here for myself but why always so theoretical, lets try it out and see what happens.and a well build marx generator with good caps can have a high current rating, you get a short high voltage high current pulse for around 100ys or so, that can ring up a secondary coil with 100khz 10 times, more than enough to ionize the air and build up a spark.
the only problem i see is the resistance of the spark gaps, this will reduce the maximum current flow
Re: New Type of SGTC?
J. Aaron Holmes, Thu Oct 05 2006, 07:10PM
One of the (related) thoughts I had a little while ago was to use Terry's SISG as the basis for an "off-line" Marx generator, operating at voltages below where a SG-based Marx could operate. Such a thing might be the basis for an OLTC.
To avoid major timing issues, the total output of the SISG-based Marx would probably have to be less than or equal to the voltage of any single IGBT. Thus a three-stage SISG Marx based on 1200V IGBTs ought to be able to easily take in 300V and output 900V, becoming a voltage tripler.
Regards,
Aaron, N7OE
J. Aaron Holmes, Thu Oct 05 2006, 07:10PM
One of the (related) thoughts I had a little while ago was to use Terry's SISG as the basis for an "off-line" Marx generator, operating at voltages below where a SG-based Marx could operate. Such a thing might be the basis for an OLTC.
To avoid major timing issues, the total output of the SISG-based Marx would probably have to be less than or equal to the voltage of any single IGBT. Thus a three-stage SISG Marx based on 1200V IGBTs ought to be able to easily take in 300V and output 900V, becoming a voltage tripler.
Regards,
Aaron, N7OE
Re: New Type of SGTC?
HV Enthusiast, Thu Oct 05 2006, 08:12PM
Not really. Single-shots are almost always shorter than continuous operation.
HV Enthusiast, Thu Oct 05 2006, 08:12PM
wrote ...
yeah i know, but whats about a drsstc in one shot mode, it does exactly the same,a long arc with the same lenght as you would usually get.
yeah i know, but whats about a drsstc in one shot mode, it does exactly the same,a long arc with the same lenght as you would usually get.
Not really. Single-shots are almost always shorter than continuous operation.
Re: New Type of SGTC?
teravolt, Fri Oct 06 2006, 04:42AM
an idea I had would be to make a PFN with a thyratron or scr. if the PFN has a pulse width equal to 1/2 cycle of the primary resonsnce the tesla should ring like bell. a thyratron or SCR should be able to do 1khz.
teravolt, Fri Oct 06 2006, 04:42AM
an idea I had would be to make a PFN with a thyratron or scr. if the PFN has a pulse width equal to 1/2 cycle of the primary resonsnce the tesla should ring like bell. a thyratron or SCR should be able to do 1khz.
Re: New Type of SGTC?
Electroholic, Fri Oct 06 2006, 11:54AM
Thyratron eh?
Electroholic, Fri Oct 06 2006, 11:54AM
Thyratron eh?
Re: New Type of SGTC?
Terry Fritz, Sat Oct 07 2006, 03:26AM
One would have to be careful of the current. It would be very nice to keep the IGBT current bellow 800 amps. Also, when the thing fires, the dI/dT would need to be slow enough for the SISG sections to turn on normally. Adding an "inductor" would fix all that
Just like a Tesla coil primary.
EVR brings up a good point about the "BPS". Less than say 120BPS might really begin to hurt the output spark length. If say inductors instead of resistors could be used, that might not be a problem..
Using inductors in the MARX strings might cause unwanted oscillations. Resistors burn up, but I had major problems at first trying to use inductors for current limiting in early SISG coils due to them oscillating with the main cap in all the wrong ways...
It might be possible to use fairly low value resistors (runs cooler). Their value would still have to be higher than the primary system impedance by say 10X.
Cheers,
Terry
Terry Fritz, Sat Oct 07 2006, 03:26AM
One of the (related) thoughts I had a little while ago was to use Terry's SISG as the basis for an "off-line" Marx generator, operating at voltages below where a SG-based Marx could operate. Such a thing might be the basis for an OLTC.
One would have to be careful of the current. It would be very nice to keep the IGBT current bellow 800 amps. Also, when the thing fires, the dI/dT would need to be slow enough for the SISG sections to turn on normally. Adding an "inductor" would fix all that
Just like a Tesla coil primary.EVR brings up a good point about the "BPS". Less than say 120BPS might really begin to hurt the output spark length. If say inductors instead of resistors could be used, that might not be a problem..
Using inductors in the MARX strings might cause unwanted oscillations. Resistors burn up, but I had major problems at first trying to use inductors for current limiting in early SISG coils due to them oscillating with the main cap in all the wrong ways...
It might be possible to use fairly low value resistors (runs cooler). Their value would still have to be higher than the primary system impedance by say 10X.
Cheers,
Terry
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