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Electronic fuse

Not like it hasn't been done before, but I decided it's about time I have some on hand.

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'Dem printed boards sure look nice for a change.

Features:

- Unidirectional

- 8A current carrying capacity (on resistance < 70mohm)

- 40V open circuit capacity

- Fault current: opens in under 10us

- Moderate overload: opens up to 1ms+ later (adjustable)

- Current limit: adjustable

- Thermally protected (~100C at R4)

- Manual set/reset (pushbuttons)

- Battery operated (180uA current draw; was supposed to be under 50uA, I need to look into that -- but still, several months on a typical 9V battery)

With some mods, it could also be tweaked for continuous current limiting (thermally protected), foldback or otherwise; automatic retry (tick-tick-tick-tick...), and various interfaces (electronic set/reset, logic level indication, battery eliminator -- isolated supply), etc. And, needless to say, scalable to whatever voltage/current rating might be needed.

Tim

--
Seven Transistor Labs 
Electrical Engineering Consultation 
Website: http://seventransistorlabs.com
Reply to
Tim Williams
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On a sunny day (Sat, 30 Aug 2014 01:50:00 -0500) it happened "Tim Williams" wrote in :

Whats that MOSFET you are using?

Reply to
Jan Panteltje

Looks like PSMN012

Reply to
whit3rd

On a sunny day (Sat, 30 Aug 2014 12:33:19 -0700 (PDT)) it happened whit3rd wrote in :

Thanks, looks like a nice MOSFET, 11mOhm..

Reply to
Jan Panteltje

,

use two FETs back to back and it'll work for AC too

-Lasse

Reply to
Lasse Langwadt Christensen

Are you sure? Looks a little rich for Tim's budget!

Jamie

Reply to
Maynard A. Philbrook Jr.

Claire (now IXYS) has some interesting self-protecting SSRs that have overcurrent and thermal limiting. They are useful just as fuses, with the SSR fiunction optional.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

:

ave

I

ng

,

And,

I thought about using two FETs and an IR2127 to protect some triacs, they won't handle a half cycle in a dead short

-Lasse

Reply to
Lasse Langwadt Christensen

Here's one way to make a self-resetting fuse:

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--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

I would've smelted my own, but darn it, I'm fresh out of phosphorus!

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Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

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Reply to
Tim Williams

Well, you made a 0 volt gate fet! Very usable in the single cell world.

Jamie

Reply to
Maynard A. Philbrook Jr.

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