Pulse signal output circuit and flowmeter

A pulse signal output circuit, comprising:

• a signal-receiving circuit, a photoelectrical coupler, and a signal conversion circuit;
• wherein the signal-receiving circuit is connected to the photoelectrical coupler, and the photoelectrical coupler is connected to the signal conversion circuit;
• the signal-receiving circuit is configured to receive a source pulse signal acquired by a flowmeter and send the source pulse signal to the photoelectrical coupler;
• the photoelectrical coupler is configured to perform electrical-optical-electrical conversion processing on the received source pulse signal to obtain an electrical signal, and send the electrical signal to the signal conversion circuit;
• and
• the signal conversion circuit is configured to perform conversion processing on the received electrical signal, to obtain and output an output pulse signal corresponding to the source pulse signal;
• wherein the pulse signal output circuit further comprises a logical NOT circuit;
• the signal-receiving circuit is connected to the logical NOT circuit, and the logical NOT circuit is connected to the photoelectrical coupler;
• and
• the signal-receiving circuit sends the source pulse signal to the logical NOT circuit, and the logical NOT circuit processes the source pulse signal to obtain and send a first sub-signal to the photoelectrical coupler;
• wherein the logical NOT circuit comprises a first current-limiting sub-circuit and a logical NOT sub-circuit;
• the first current-limiting sub-circuit is connected between the signal-receiving circuit and the logical NOT sub-circuit;
• the logical NOT sub-circuit is connected between the first current-limiting sub-circuit and the photoelectrical coupler;
• the first current-limiting sub-circuit receives the source pulse signal sent by the signal-receiving circuit, and performs current-limiting on the source pulse signal to obtain a current-limiting signal;
• the first current-limiting sub-circuit sends the current-limiting signal to the logical NOT sub-circuit;
• and
• the logical NOT sub-circuit performs reverse processing on the current-limiting signal to obtain and send the first sub-signal to the photoelectrical coupler;
• wherein the logical NOT circuit further comprises:
• a third resistor, a third capacitor, and a fourth capacitor;
• the third resistor is provided between a power pin of the logical NOT sub-circuit and a first power supply;
• the third capacitor is provided between the first power supply and ground;
• and
• the fourth capacitor is provided between an output pin of the logical NOT sub-circuit and the ground.