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My first ZVS

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Whiplash

Tue Mar 26 2013, 01:36PM

Registered Member #11363 Joined: Mon Mar 18 2013, 04:29PM
Location: Brazil
Posts: 19

Hi all ppl. Im new here, more than 2 years that i read the forum, but only now i want to show some of my circuits
ps: im from Brazil, my english is poor.... i will try to do my best :D
here a video of my first zvs:

Its uploaded on 4shared, because youtube are blocked here at my work ^^
My ZVS are made with 2 fet IRF3205 (55v / 110A 8.0mOhm) , have 5+5 turns of a 0,8mm cooper and the supply is a transformer from a nobreak and gives 22V at 15A +/- , have 21.500uf for filter.
A traditional flyback from a crt monitor. The indutor i got from a atx psu.
diodes zenners are 12v 0,5W and the diodes are UF4007.
My only problem, is the fets burning with +/- 5 minutes of working...
Next weekend, i want to try to do a tesla :D .

Tony Matt

Wed Mar 27 2013, 12:26AM

Registered Member #3700 Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107

Hi !
Do You mind to post a complete schematic with all material data ?
Regards
Tony

Whiplash

Wed Mar 27 2013, 01:05PM

Registered Member #11363 Joined: Mon Mar 18 2013, 04:29PM
Location: Brazil
Posts: 19

Of course, sorry for my mistake, its because ZVS Schematic are easy to find on google^^
I use this schematic:

this is with P80NFS fets

IRF3205

my Power Suply ^^

and my first experiment for a tesla: 84 turns 0,84mm wire on 60mm diameter.

FETS: IRF3205 / P80nFS are good too.
CAP: 220nF MKP
Zenners: 12v 1W
Resistors 470ohms 7W
Resistors 10k 1/4w
Diodes: Uf4007.
i will edit the first post, and put a picture of the board :)
*idk how to put miniatures =/

Tony Matt

Fri Mar 29 2013, 02:31AM

Registered Member #3700 Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107

Hi Whiplash !

Thanks for the schematic, now I can see the circuit....
Thanks

the mad scientist

Fri Mar 29 2013, 04:28AM

Registered Member #3768 Joined: Tue Mar 22 2011, 12:46AM
Location:
Posts: 107

Nice, I am the opposite of you, I am nearly done a Tesla coil and have yet to make a ZVS lol.

Whiplash

Tue Apr 02 2013, 06:24PM

Registered Member #11363 Joined: Mon Mar 18 2013, 04:29PM
Location: Brazil
Posts: 19

i will try today to maka a tesla ^^
someone can say, what its better between zvs x 555? (for a small tesla coil?)

Kiwihvguy

Wed Apr 03 2013, 12:37AM

Registered Member #3395 Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193

Hi Whiplash,

Re. the fets burning up within 5 or so minutes of operating in ZVS, I think this is quite normal. Fets can heat up quite quickly in a ZVS especially if running it pretty hard. I would make sure you've got a sufficiently big heatsink and some thermal grease to increase the thermal conductivity between the back of the fets and the heatsink.

Also do be aware that the maximum rating of fets will decrease as their temperature increases. For IR3205 fets, the current capability decreases to 80 amps @ 100 deg Celcius though I don't think this is a problem. It's more likely a voltage spike that killed the fets becauses they're only rated for 55v. For more reliability I would get fets rated into the 100s of volts.

Try improving this if you can as I'm sure it will help and let us know if you have any problems.

Kiwihvguy

Wed Apr 03 2013, 07:23AM

Registered Member #3395 Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193

Also, would it be possible to take some current nd voltage measurements of the ZVS circuit running? The values you've said for the transformer power supply are probably the no load voltage and maximum current rating, if not correct me but I'm just assuming.

You will probably find that the voltage will drop due to the internal resistance of the windings in the transformer (depending on how well it's made) and the current will peak quite high when you are arcing.

Whiplash

Wed Apr 03 2013, 03:51PM

Registered Member #11363 Joined: Mon Mar 18 2013, 04:29PM
Location: Brazil
Posts: 19

Jozef C. I will try to buy better fets today. About my power supply, its 22V and more than 20A now (better bridge for 50A). I use an "shower resistance" to test him up, and give me this values, have a ammeter analogic and goest to 22A with that resistance.

Kiwihvguy

Thu Apr 04 2013, 04:04AM

Registered Member #3395 Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193

Ok - just clarifying, would you be able to measure the current drawn when you are drawing/stretching the arcs out? Because from there I could calculate the power your IRF3205s would be dissipating and this would be helpful just to get an idea of how we should be wary of heating.

Don't worry about buying new fets soon - there's no rush. Some fets are very expensive so don't spend all your $$$ on high power ones. I think the IRFP250 (200 volts 33 amps) or the IRFP260 (200v 46 amps)would be suitable for yours (it's the generic mosfet used in the ZVS circuit).

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