find the speed of the DC motor using proximity sensor

[selva murugesan]

Hello experts

In my project , I want control & display the speed of the Wiper Dc motor(12v,5v). For this I am using the PIC 16F877A and IRFP150n (MOSFET).
Now I control speed of the motor with help of PWM. I am using the proximity sensor to sense the speed.for my problem , how can get the speed with help of the proximity output signal. the speed range is 10-50rpm. what is best method to get the speed?

 

[embpic]

for presise roatation of DC motor following link help you.
https://www.romanblack.com/onesec/DCmotor_xtal.htm

 

[selva murugesan]

hi friend,

thanks for reply.

I understand the circuit.Not only in this circuit , generally ,more people are using 20Mhz(crystal) for control such like low speed control. May i know any specific reason for this?