This is my another Instructable Contactless Tachometer using Arduino and IR sensor. I inspired to make this project when i need to measure the RPM of DC motor, then I started to make contactless tachometer. the main advantage of this project is that it can measure the rpm of very low power motors, because it don't need to touch the axis of motor. you can make this using 8051 and PIC microcontroller
Step 1: Working
IR sensor can differ the white and black color, when it is in front of white part it will give output as HIGH and when it is in front of black color output as LOW. The output of IR sensor is connected to counter pin (D3) of Arduino which is INT0.
For the measurement of RPM attach a white line over a black part which will attached to axis of motor. Rotating circle is shown is images.
Step 2: Collect the Material
1. Arduino UNO
2. IR sensor
3. LCD Display
4. Power Supply
5. Motor for Rpm Measurement
6. 9 volt battery
Step 3: Circuit Diagram
We need two circuits 1st is for speed control of DC motor, its very simple circuit but use a good quality motor because magnetic field of dc motor can disturb working of sensor
Second circuit is our Tachometer circuit.