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Originally Posted by Biff
I like the design, but after exhaustive research, the only acquireable parts are surface mount. Not a DIP in stock at the approved vendors or even some brokerage houses. He mentions the resistance of the 20 amp fuses at about 9 milliohms and the 30 amp at about 6 milliohms. I don't have a meter that will get me readings that low.
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Biff,
Op amps are pretty "vanilla" in that you can drop almost any device in place for a given circuit and it will work. In this application you do need a low input offset voltage specification. I remember at the time that a lot of discussion occured over different methods of measuring current. While the breakers do exhibit some resistance, this a variable especially if the breakers have ever tripped. We used the resistance across a 1 foot long #10 guage wire as it is close to .001 ohms/ ft. Remember to measure the current on the supply side of the speed controller as this doesn't change polarity.