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I tried to make a ZVS from junk.

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LAN_403

Platinum

Tue Dec 27 2011, 12:44AM

Registered Member #3926 Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525

I did try to make a ZVS from junk, it's not working though, for the FET's I'm using (

And I'm using some random 12v zenners and 2 1n4007 diodes. and I couldn't get 10k's so I have 15k's on hand.

Marko

Tue Dec 27 2011, 01:04AM

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

Hi

Oddly your datasheet link returns results for LM324, I assume your mosfet is 21N50 though.

To spare us of all speculation, could you please post a single detailed picture of what you've made? The help would be tremendous.

Marko

Platinum

Tue Dec 27 2011, 01:55AM

Registered Member #3926 Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525

Yes I got the mosfets from a PSU, I also have 13nc50?somthing's

Sorry I do not have a very good camera it also won't focus to macro.

Sorry this is the best, I used solder is it's very easy to construct, and all the solder is 0v.

,yiJbT,aZ8eV#0

Inducktion

Tue Dec 27 2011, 02:13AM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

Eh..... I can't understand what's going on there. Make the connections MUCH smaller; You don't need the solder leads between the fets. You'll also need a heatsink. And the two "470" ohm resistors should be similar. You're using two different ones there. They don't necessarily need to be 470, though, anywhere from 300 to 1k will work.

Platinum

Tue Dec 27 2011, 02:41AM

Registered Member #3926 Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525

Dr. Duck wrote ...

Eh..... I can't understand what's going on there. Make the connections MUCH smaller; You don't need the solder leads between the fets. You'll also need a heatsink. And the two "470" ohm resistors should be similar. You're using two different ones there. They don't necessarily need to be 470, though, anywhere from 300 to 1k will work.

Sorry it tried to make it from junk, and yes sorry about making the leads to long. I have rearranged the resistors, and I'm using two 470ohm ones to replace the two 1k resistors.

When I first made the circuit my PSU, wouldn't short circuit, but I detected that a 12v zenner was connected in reverse, so I put the zenner like the should be and now the PSU short circuits?

Even then there is no output, I wasn't expecting it to work anyway.

Marko

Tue Dec 27 2011, 02:41AM

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

Platinum wrote ...

Yes I got the mosfets from a PSU, I also have 13nc50?somthing's

Sorry I do not have a very good camera it also won't focus to macro.

Sorry this is the best, I used solder is it's very easy to construct, and all the solder is 0v.

,yiJbT,aZ8eV#0

Yeah, indeed very confusing and hard to figure out both for you and us. Also, that's not all of it, I suppose you have a flyback and a tank cap connected to it too?

Try this:

Leave out zeners (for 12V runs), 10k resistors (you don't need those at all, ever), and try to find two equal pullup resistors. They don't need to be as big for start, 0.5W is OK and just make sure resistance is somewhere in range from 330 ohms to 1k or whatever.

Later, you can add zeners (just solder them directly between mosfet gate and source, can't be simpler!)

The thing most people miss is that you need a low loss polypropylene tank capacitor, and tend to put everything there which either doesn't work or swells and dies after a while.

Of course, make sure to verify if your mosfets are still working before venturing further.

Marko

PS. Hard to make out on the pic, but are you completely sure you aren't mixing drains and sources on the mosfets?

Platinum

Tue Dec 27 2011, 03:18AM

Registered Member #3926 Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525

I think I'am mixing the drains, with sources.

I'm using the schematic.

I just added two new 12v zenners.

Why does the supply short when I turn the ZVS on?

Marko

Tue Dec 27 2011, 03:54AM

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

Why does the supply short when I turn the ZVS on?

Well, something may be wired wrong, or you have already blown mosfets with previous experimentation. If you indeed used car batteries for power they probably died already.

The Lightning Stalker

Tue Dec 27 2011, 04:10AM

Registered Member #4230 Joined: Sat Nov 26 2011, 05:50AM
Location: Socketville
Posts: 53

I've blown MOSFETs before by just touching the gate lead with my finger. Are you sure the MOSFETs are good? If you have a multimeter with a diode test function, I'd test the diodes as well. With junk parts you never know what is good and what is blown.

Platinum

Tue Dec 27 2011, 04:17AM

Registered Member #3926 Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525

Yes I've rested the MOSFET's and they are OK. Zenners are new and are OK, and diodes are good. Is the power supply mean't to short circuit? Atm, I'm not using batteries, I'm using a 19v 3.45a SMPS.

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