This is a very intresting project and utlize very less efforts lts make a very simple RPM meter (Round Per Seceond In my case).
Step 1: OP-Amp
This is a magic ic(LM358) it can be used as analog output (constant gain amplifier), Or digital Output Eg- either output is HIGH or LOW means 0 and 1,
in this case we use use this as Digital Output (comparator Mode).
Step 2: IR Led or IR Senser
IR led emmits ir light, in opposite IR senser detects it if IR light is reflected on IR senser it starts conducting,
Step 3: Schematic Diagram
Assemble all components according to circuit diagram, you can also purchase ready made IR module from market,
Ir modules have 3 pin
1. Vcc connects to +ve of supply
2. Gnd Connects to -ve or 0v
3. Output Output is connected to any module (in my case input of Frequency counter)
Step 4: How RPM Measured
Cover Moter shaft with white paper then colour half paper with black marker or pen, according to Picture when moter start rotating black and white surfaces come infront of IR led Or IR senser , when black surface comes then IR light reflects in case black surface IR light can't reflect , this cause oscillation with respect to moter speed and calculated by Frequency counter Frequency Counter you can also watch my video Click here for deep details.
Step 5: Moter Shaft and Working of IR Module
As shown in picture place IR module near Rotating moter shaft.
Step 6: DIY IR Module
You can also make this or purchase it for rs 100 from market,
Step 7: Frequency Counter Wireing Connection
Connect All 3 wires of IR module to frequency counter.
Step 8: Frequency Counter
You can use this DIY frequency counter or Use Oscilloscope to measure Rotation speed.
Watch video of Frequency Counter Frequency Counter
Make Your Own
leave a comment if you have any problem
C U soon