Hey
Trying to measure the voltage of a 100Amp-60mV Shunt. I have put together a circuit consisting of a lm358 opamp that should gain up the signal by about 54. The high current circuit is fed from a different power supply then the conditioning and monitoring circuit.
At first i appeared to be get mV losses in an about a 1 foot run of 1.5mm square cable going from the shunt to the op-amp circuit is this possible (gain of circuit appeared be at about 20) ? Also my multi-meter appeared to effect the shunt signal is this because it would be considered a very high impedance source and therefore the multi-meter was loading it too much? I moved the circuit right beside the shunt and that improved things alot however i'd like to know what is the best way to take a signal from a shunt i.e should i use ground isolation, an istrumentation amplifier, should i use certain cable, how would i determine the necessary op-amp input impedance to read the shunt?
Any sugestions appreciated!!
Mike
Trying to measure the voltage of a 100Amp-60mV Shunt. I have put together a circuit consisting of a lm358 opamp that should gain up the signal by about 54. The high current circuit is fed from a different power supply then the conditioning and monitoring circuit.
At first i appeared to be get mV losses in an about a 1 foot run of 1.5mm square cable going from the shunt to the op-amp circuit is this possible (gain of circuit appeared be at about 20) ? Also my multi-meter appeared to effect the shunt signal is this because it would be considered a very high impedance source and therefore the multi-meter was loading it too much? I moved the circuit right beside the shunt and that improved things alot however i'd like to know what is the best way to take a signal from a shunt i.e should i use ground isolation, an istrumentation amplifier, should i use certain cable, how would i determine the necessary op-amp input impedance to read the shunt?
Any sugestions appreciated!!
Mike