As shown in the figure, the current of the transmitting tube is 40mA, and the voltage of the op amp at the receiving end is only about 200mv. It feels like the voltage generated by the dark current, and the receiving tube is not turned on.
Please help me find out what went wrong?
Aidan ポストする October 27, 2020
What is your OPA——PWR, power supply? Why provide a working model for the voltage division, and this common-mode voltage is further amplified in the following circuit.
Ian ポストする October 27, 2020
According to my analysis, the output of the op amp U4A Vo=VOPA_PWR*10/(10+47)+Id*(2M+100k)
Id should be pA level
U4B output=Vo*(1+30/20)
R14 should indeed be removed. According to the modification in the figure, the problem should not be big. The original poster first check the power supply of the op amp.
Brian ポストする October 27, 2020
Then disconnect the 0R resistor in your middle for first level debugging.
Is your receiver infrared?
