1. The lower left corner is the filter circuit for power supply access;

2. From left to right, the first amplifier is an amplifier circuit, which amplifies the input small signal, but the output may be irregular;

3. The second amplifier is a shaping circuit, which shapes the amplified waveform into an approximate square wave;

4. The fourth amplifier plays the role of inverting, that is, inverting the signal180;

5. The fifth amplifier and the following amplifiers are output amplifiers, which are set to improve the output capacity of the circuit. Sometimes called isolation amplifier, it is designed to isolate the influence of internal circuit and output external circuit. The difference between the outputs of these two amplifiers is that their phases are opposite. The user can select the appropriate output terminal.

To sum up, this should be the input signal processing part of a pulse counting circuit.