1. As can be seen from the above figure, the first stage is a transimpedance amplifier (which can be understood as an I/V converter). It converts the current generated by photodiode into voltage and outputs it to the output pin 6 of the first amplifier, and the connection is normal.

2. The second stage is an in-phase proportional amplifier, but the right end of R5 in the above figure is suspended, so it should be connected to the output terminal 5 of the second stage amplifier OP07C to form negative feedback, otherwise the second stage is open-loop and the output voltage is uncontrollable.

Connect the right end of R5 to pin 5 of OP07C, and take a good look ~ ~ I hope you will succeed ~ ~ Welcome to the discussion!

In addition, when designing the circuit:

1. If an operational amplifier is involved in the circuit, it will generally constitute a feedback access circuit;

2, if used as a comparator, generally open-loop access circuit.

I hope it helps you ~ ~