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new drsstc based upon my new driver topology(Musical DRSSTC)

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LAN_403

Bauerb2

Mon Dec 17 2007, 12:39AM

Registered Member #973 Joined: Tue Aug 28 2007, 07:32PM
Location: Pittsburgh, PA
Posts: 66

that secondary is beautiful, no problems at all. smooth and nipple-free.

Reaching

Wed Jan 02 2008, 09:05PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

some new infos.

started putting the parts in a nice case with aluminium front and back. secondary and primary are finished, driver and bridge pcb finished and tested.

made some 30v tests today and everything seems to work fine, 8cm streamers with 50A peak at 300ÂµS on time at 30v input. finished the mmc and within this week i think i can make the first high power tests.

this new design with higher voltage gdt drive is really interesting. rise times below 50nS with 8nF load on 1 gdt are possible. with my hameg204 scope the rise time of the bridge output is hard to measure. only 30nS or so. ok, not close to the rise time a high side driver can reach, but for as gdt design i think its more than ok..

more to come soon

Reaching

Sat Jan 05 2008, 08:55PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

Okay, first full voltage test was promising, but i really need a strikerail before i can go full power.

distance was around 70cm, not too much but really good for 220A ocd limit

Marko

Sat Jan 05 2008, 09:14PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

How do you manage 70cm with just 220A of primary current?

It took mine like 500+ amps. What is your surge impedance?

Reaching

Sat Jan 05 2008, 10:15PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

mh, the whole thing is build for long time and high duty cycle operation. the sparklenght itself was not my only goal. i wanted to build a reliable drsstc for demos, which can run several minutes without getting too hot or ending in a disaster of blown igbts.
what do you exactly mean by "surge impendance"? ok, im not really the pro in formulas and such things, but i measured the things i can with my equipment.

so the mmc has 169,1nF capacitance and the primary is tapped by 12,9ÂµH . resistance of 8,1mohm. in my previous tests i calibrated the ocd, so i think its working "exactly". so i turned the pot for 2.13volts, which means 213A primary current. with delay etc im close to around 220 to 250A.

the interrupter was set for around 80 to 100ÂµS ontime, and 5,2mS off time.

heres a pic of the finished drsstc components

this was my first test with my new driver and i think its working really good so far. well, im in the testing phase and i really need a strikerail to go further. had several pri sec arcs, and i dont want to destroy my work..

Experimentonomen

Sun Jan 06 2008, 12:09AM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

Woot!! Very nice!!

Austin

Sun Jan 06 2008, 03:52AM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

very clean... and shinny. Keep up the good work

Dr. H.

Sun Jan 06 2008, 09:22AM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Are you going to put a fan on that box (i can't see it so just a suggestion). Keep up the good work

Logan Kennedy

Sat Jan 12 2008, 05:16AM

Registered Member #1103 Joined: Mon Nov 05 2007, 06:02PM
Location: Houston
Posts: 80

What kind of capacitors are you using for the MMC?

Good setup! I really like the layout of your pc boards.

Reaching

Sat Jan 12 2008, 08:54AM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

for the mmc i use wima fkp1 caps. here in europe wima is one of the largest manufactures for pulse application capacitors. i never had problems with wima caps so far. in my other drsstcs i used wima mkp10 caps, which are much cheaper, but the fkp1 are real metal foil caps and can stand up large currents. the mkp10 are metallized foil but worked for me in all of my other drsstcs for long time without a failure ever.

i tuned the drsstc and im surprised to get around 78 to 80cm discharges with 160ÂµS on time and overcurrent set to 300A . The led doesnt light up.
but as i tuned and measured the frequency and some other things, i got worried..
in an ordinary drsstc setup the waveform is zero between on time pulses. this is the case, but i got worried about a pulse which comes up around 10ÂµS after every on time pulse ending. it looks like some sort of ringing, but i could not find the cause of this pulse. i rebuild the driver part and tested it and i get the same pulse.. its only one small pulse, but it turns on the igbts. its not a feedback failure. it does exactly the same with an ordinary external oscillator.. the failure must be in the driver part itself. if someone is interested i can post a scopeshot and a shematic of the driver part im using

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