ikorman
Junior Member level 1
Hi there
I have built motor test stand for brush less motors for my RC equipment (testing RPM, thrust, etc.). One of the thing I would like to add to my system is motor current measurements capability. I have chose to use shunt resistor which for 100A gives 75mV, which I will connect to my Arduino board and use ADC to sample shunt voltage and calculate the current.
My problem is how to design quality opamp circuit that will bring voltages from 0-75mv range to 0-5V. As I want to measure currents with precision of at least 0.1 A, that means that I need to able do measure voltages from 0.1 mV or less. I'm not so good in pure analog electronics (I'm more digital/uC oriented guy ;-)), but I'm aware of of problems like rail-to-rail inputs, offset voltage, inputs near zero, noise and similar things regarding opAmps. I would like to use something like AD620 or similar (precise, high gain, very low noise, etc.)
What would you recommend for me for this particular use case? Would AD620 work for this?
Many thx.
Ivan
I have built motor test stand for brush less motors for my RC equipment (testing RPM, thrust, etc.). One of the thing I would like to add to my system is motor current measurements capability. I have chose to use shunt resistor which for 100A gives 75mV, which I will connect to my Arduino board and use ADC to sample shunt voltage and calculate the current.
My problem is how to design quality opamp circuit that will bring voltages from 0-75mv range to 0-5V. As I want to measure currents with precision of at least 0.1 A, that means that I need to able do measure voltages from 0.1 mV or less. I'm not so good in pure analog electronics (I'm more digital/uC oriented guy ;-)), but I'm aware of of problems like rail-to-rail inputs, offset voltage, inputs near zero, noise and similar things regarding opAmps. I would like to use something like AD620 or similar (precise, high gain, very low noise, etc.)
What would you recommend for me for this particular use case? Would AD620 work for this?
Many thx.
Ivan