Flyback Driver inside a PC PSU box / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Flyback Driver inside a PC PSU box

previous 1 2 3 next

Move Thread

LAN_403

TheMerovingian

Tue Feb 06 2007, 10:10AM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

I am a bit warned by safety. You should use a ceramic insulator to hold the hv wire. If you accidentally brush your hand on that thing, touching the metal case, you will get a nasty burn on your hand .

Dr. Dark Current

Tue Feb 06 2007, 03:31PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

hmm, those are really scary arcs bp

, I think my flyback could also do such arcs but i want it to last and not melt after 20 seconds

(i can run it for hours just fine)
And theres aproblem with the "zvs" driver that the primary gets nasty hot even if you use thick wire and if you wand it to run directly from mains you need xpensive hv fets. (my halfbridge overcomes all these problems i think

)

btw. BP, how much power did you get in that arc? My flyback does not make very high voltage ,so it takes around 350w to stretch the arc to ~12cm, butthe arc is very hot (i calculated about 70ma of current)

Marko

Tue Feb 06 2007, 03:45PM

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

I think blackplasma used 4 flybacks..in parallel, there?

I am a bit warned by safety. You should use a ceramic insulator to hold the hv wire. If you accidentally brush your hand on that thing, touching the metal case, you will get a nasty burn on your hand .

Only thing I trust is a 2 meter long chicken stick.. I wouldm't be anywhere near the box while it's running anyways...

uzzors2k

Tue Feb 06 2007, 07:41PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Nice job jmartis. What kind of driver is it, just a tl494->halfbridge thing? How many turns are you using on the flyback primary?

Dr. Dark Current

Tue Feb 06 2007, 08:31PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

uzzors wrote ...

Nice job jmartis. What kind of driver is it, just a tl494->halfbridge thing? How many turns are you using on the flyback primary?

Hi uzzors, thanks, it uses ir2153 halfbridge driver ic to drive irf740 halfbridge (no gdt's requied), operating frequency ~30k. There are 30 turns of pvc-insulated wire on the primary.

My fuse kept blowing (the caps acted as a short when empty) so I included a charging circuit that consists of a charging resistor and a relay delay (

) circuit, that shorts the resistor after the caps have charged. I think it works quite well.

Edit> I just found that the metal case around the flyback secondary is heating a bit, what is causing this? I hope it doesnt reduce performance too much...

Steve Conner

Tue Feb 06 2007, 10:26PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Good work jmartis! Most hobbyists seem to have real trouble getting those IR half-bridge driver ICs to work well.

Marko

Wed Feb 07 2007, 09:24AM

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

My fuse kept blowing (the caps acted as a short when empty) so I included a charging circuit that consists of a charging resistor and a relay delay ( ) circuit, that shorts the resistor after the caps have charged. I think it works quite well.

You can use an NTC thermistor (from ATX supply, same purpose) to limit the inruch current to caps.

It's just connected series with AC input.

Relay circuit is surely better, but not as cost-effective solution.

Dr. Dark Current

Wed Feb 07 2007, 02:04PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Steve CÃ¸nner wrote ...

Good work jmartis! Most hobbyists seem to have real trouble getting those IR half-bridge driver ICs to work well.

Thanks. No trouble here, i've made a few fbt drivers with this ic before, and everytime it worked on first light.

Firkragg wrote ...

You can use an NTC thermistor (from ATX supply, same purpose) to limit the inruch current to caps.

It's just connected series with AC input.

Yes I tried this, but after the thermistor heats up and you relatively fast turn it off-on, it can also blow the fuse.

uzzors2k

Wed Feb 07 2007, 06:10PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

How do you guys get such massive arcs? Special flybacks? I tried with 24 primary turns directly off mains, but the arcs are still only around 6 cm.

1170871805 95 FT20246 Offline Flyback Arc

Dr. Dark Current

Wed Feb 07 2007, 07:17PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

uzzors wrote ...

How do you guys get such massive arcs? Special flybacks? I tried with 24 primary turns directly off mains, but the arcs are still only around 6 cm.

My arcs are about 12cm when stredched vertically and maybe 7cm horizontally, how did you measure it? No special flyback, just old AC one, that can put out more current so that maybe explains why the arcs can be stretched further, but I'm not really sure

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob