Or a processed speed module.
Here's the process
* * * * * * * * * * * * * * * * * * * * * * * * * * When the measured object rotates, the two feet will output a DC pulse signal that changes in height.
* When P2 outputs a high level of 24V, the current at the base of Q3 will be (24-0.7)/4.7mA, and the voltage at the saturated collector of Q3 (P3.2) will be 0v; *
* If P2 is the output high resistance of OC gate circuit, the base of Q3 will have a current of (24-0.7)/(4.7+4.7)mA, and Q3 will also saturate the collector (P3.2) with a voltage of 0 V; *
* When P2 outputs 0V at a low level, there is no current at the base of Q3, and the voltage at the cut-off collector (P3.2) of Q3 is 5 V..*