I am trying to convert 4-20 mA current loop signal to 0-3.3/0-3 V output for my 10 bit ADC IC that is connected to a Raspberry pi 3B+.
Schematic:
The input sensor is a 12 V loop powered 4-20 mA output humidity sensor. The op-amp is an MCP6002 rail to rail. The output of the op-amp is connected to a 10 bit ADC-MCP3008 (SPI enabled connected to RPi.)
The output voltage only varies from 0.6 to 2 V and I don't know where exactly the voltage drops.
The circuit works fine if I read the voltage using only a 150 Ω resistor (0-3 V.)
I can't understand what's wrong in this circuit.
Prior answers related to this question didn't give the solution. Please help me to find a reliable solution.
JoannMatheson
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Joined June 12, 2023 2Monday at 04:10 PM