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cut pattern to modify fat shunt
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coppercone2:
So I have a shunt hooked up to a meter (kelvin, mOhm), and I want to cut it in order to increase its resistance if possible, probably with a dremel.
What cut pattern is good to use (I guess similar to what they do with laser cutting foil resistors?)
It's one of the chinese ones that connects to a panel meter, the idea being to reduce a 50A shunt to 5A so the scales work.
I was going to use a serpentine cut
SeanB:
Is it AC current, where using a current transformer will probably be a better bet. A small strip toroid ( or an old small mains transformer you have cut the windings off without disturbing the core itself) with a secondary of 1 turn of thick copper wire, around 16mm, and a primary winding of 10 turns of 1mm copper wire. Simple, reliable and much lower error as well instead of destroying the shunt itself.
I use one to increase the sensitivity of a regular power meter, as I wanted it 10 times more sensitive, so used an old 35W toroidal transformer for the core, and the current sense winding now is running at 8A peak , but the internal sense coil still has up to 80A flowing in it.
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