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Registered Member #4014
Joined: Wed Jul 20 2011, 05:31PM
Location: SE Michigan
Posts: 25
Its now my second flyback here since my last one got too hot and arced over soon after it became AC. My ZVS has IRFP260N's and 15v 1W zeners and .60uF of capacitors (they get hot but they have been handling themselves very well)/
With my audio transformer here, I am inputting 59VDC when the driver is on "idle" (no arcing) and at full arc length the voltage drops down to 38VDC.
The arc length on this flyback started at about an inch and drew to about 4-5 inches and the arcs were completely silent besides minor humming. Now after lots of heating and abuse the arc starts about 1 to 2 inches and when it it is drawn to about 5 inches it screeches loudly until 6 inches. It seems like it is AC, but both poles are still unable to arc to ground unlike my last transformer that became AC which both poles arced to ground.
Ill have some more information later as I will do some fast resistor changes for up to 60-70V input on the ZVS not counting he option for dual power supplies and feed the flyback 72V (may need higher voltage mosfets for that much). I will also be trying paralleling and or series flybacks which is said to have a large difference when the input PSU can supply the current.
Since you are done reading this, here you go next: *http://www.youtube.com/watch?
v=s4V7j3HEaOE* ***http://www.youtube.com/watch?
v=mia0_SkjjFA***
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Sounds like the frequency drops under load. Once the frequency drops much below 20 kHz, it enters the 'audible range', so you hear a high-pitched screech. Does the screech change in pitch as you draw the arc further?
Registered Member #4014
Joined: Wed Jul 20 2011, 05:31PM
Location: SE Michigan
Posts: 25
Yes, I am sure it does since the power supply voltage changes so much. But the flyback never made those sounds before until these last few abuses that it now screeches. Mmmm, it possibly changes at distance, I will check tomorrow since it put away now. I think this is the warning that the internal diode is just about to call quit.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
Wow! .. you are very brave with your PC in the first video at about 36 seconds in you can see the eht going to the mat via the CD. It would be possible for the eht to track across the cd, jump to the battery then the keyboard forms a nice earth return path through your PC. ... not good.
I liked the Jacobs ladder video..nice electrodes, good effect ...I'll copy it!
I think that a separate low voltage for the gate drive circuitry is worthwhile because - if you apply the gate drive power first the zvs always starts up properly .. common is one side overheating. - if you remove the gate drive power after the main power the zvs 'shuts down' nicely .. all the energy in the resonant circuit. - a solid supply of 15 to 20 V allows lower value gate resistors which helps with switching the above may not be true but that's how it seems to me. I use a 12V 7A.h vrla battery because I usually have one handy. For big mosfet/igbt gate drive maybe 2x series 12V battery .. I haven't tried. I think it would be worth your while to try a separate gate drive power supply.
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Flybacks Change at High Powers.
