Quote:
Originally posted by JoeJ
Low resistance shunts are also allowed in the rules. They must be in the custom circuit box and will require amplifiers to be useful.
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Let me ask why you would want to add any resistance into the circuit when you can use the resistance that exists there already?
(and is required by the laws of FIRST 
)
We measure the voltage drop across the small circuit breakers. If I recall they have resistance of abot 5 and 8 milliohm
(for 30 and 20 amp breakers respectively), and since they are already present and required you are NOT adding any drops or power-losses to your circuit.
All you have to do is build a difference amplifier with a common-mode input voltage range that includes it's Vcc rail.
(and slighltly above) All this takes is a single OPAmp and 4 resistors.
If anyone is interested, I can share our schematic for this.
(in PDF format)
-Quentin
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