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Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
The images/colours you see here are a very good representation of what I see in real life... the 'blue plasma brush' pic has an exposure a little long... but the streamers are very full, VERY hot, very silent..
The colour changes, too: Initially they're your typical corona purple colour. As the copper wire heats up and starts to ball, they go light and lilacey... and as the PVC starts to smoke, they take on a blue and red tinge depending on the proximity to the fumes. The presence of burning-flesh-fumes makes the arc go yellow. ^^
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
m, omg, can you post a pic of your finger from 5.th pic
(ps. don't say it was birthday attraction for girls or something )
Anyway nice pics, what arc length do you get..?
Both use a single IRFP450 running in class-E configuration with resonant-circuit gatedrive.
One thing I wonderedis, is resonant gate drive actually more efficient than 'normal' (not counting that it is way easier to drive)
I'm using common resistive drive and putting stress to UCC, while it may not be important at all..? Problem on a fixed board would be if I replace mosfet's I would need to retune the choke somehow too..
Registered Member #63
Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425
wrote ... m, omg, can you post a pic of your finger from 5.th pic
'fraid there was no marring of my finger -- I flicked the discharge really only long enough for the camera.
wrote ... Anyway nice pics, what arc length do you get..?
The blue arc drawn to a screwdriver (in the images above) was probably just under two inches in length.
wrote ... One thing I wonderedis, is resonant gate drive actually more efficient than 'normal' (not counting that it is way easier to drive)
Depends what the amplitude of the sinewave is, whether or not you have a DC bias applied to the gate, the Q of the circuit, etc. I can keep my UCCs a lot cooler because I'm driving a small GDT +/- 12V with a stepdown ratio of about 4:1 - so the current is stepped up four times... and the voltage resonates back up to what I was driving the primary with anyway. =-D
It's quite fiddly to tune though, especially at 6.5MHz.
I'll be using IRF510s in the final gatedriver stage on the 12MHz model.
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smaller coils (and a 12MHz target)
)
