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X-Recipient:	geda-user AT delorie DOT com
Date:	Tue, 15 Apr 2014 19:54:25 +0100
From:	Richard Bown <richard AT g8jvm DOT com>
To:	geda-user AT delorie DOT com
Subject:	[geda-user] printed meter shunts
Message-ID:	<20140415195425.37808583@richard-laptop>
Organization:	Ham radio
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Reply-To:	geda-user AT delorie DOT com

Hi,
I thinking of playing with the LTC1645 using its for over current shut
down,
it requires only 50mV across a shunt resistor to trip, at 10A thats
5milli ohm.
And those resistors in TO-220 packages are expensive, so I was thinking
why use a length of wide track, needs to wide as handling up to 10A .
Are there any tables to give track resistance if the thickness , width
and length are known.
In practice its better to go for a lossier track and tap the voltage
across it with a potential divider, so target around 10 - 20 milli ohms,
cant use anything bigger as the board will get hot, 10A through 0.02 R
is 2 W, so better around 0.01 R

Thanks

-- 
-- 
Best wishes /73
Richard Bown
Email : richard AT g8jvm DOT com   
HTTP  :  http://www.g8jvm.com
nil carborundum a illegitemis
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