MOSFETS

[duc916]

Yeah $10 for a tiny tube isn't cheap, but this stuff is proven with hardcore PC overclockers.

 

[Mooch]

I should have clarified what I meant by a dead short. A short across the MOSFET, essentially closing the switch and firing the atty (indefinitely if unattended).

There's no guarantee it will only fail in to an open circuit. They could as easily fail closed.

Ahh, thanks. Agreed.
In fact I can't remember the last time a fet failed open.

 

[Mooch]

Seems to me a chassis-mounted mosfet with a coat of thermal grease would have a much better chance of a long life than one wrapped in heatshrink. Ive always thought that was kinda... crazy.

LOL, you aint kidding! But if they can hold down the dissipation to under a couple of watts, it works. That huge TO-220 could be replaced by something so much smaller with a bit of thermal management though.

 

[Mooch]

Heard of the grease too. Heat shrinks is another story. I read some say heat shrinks are not goo to wrap around the mosfet as it retains the heat longer rather than dissipating it...


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It's true. But you might not have a lot of options depending on your build. Since it's inside an almost sealed box there's not much cooling going on anyway. Best to just set things up so that it doesn't get hot in the first place.

Thermal epoxy is a great way to mount a mosfet to the inside of a metal case without having to drill a hole. The power levels are low enough to not be a problem due to the epoxy not conducting heat as well as the good greases/pastes. Just apply a smear and press out as much as you can when mounting to form the thinnest layer possible. Then clamp into place until cured.

Replacing the mosfet if it blows is a little tougher though.

 

[duc916]

I think copper is one of, if not the best thermal conductor known to man, so I would think a full copper box mod would be the ideal candidate for chassis-mounted fets. Premium CPU heatsink fans are almost always made of pure copper.

 

[HardCoil]

I am glad to have you guys here lol. Puts things to alot more perspectives. I have a few ideas to make. Box mods, tube mechs BUT the tube mech is a hybrid of wood and copper XD


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