A compact, non-contact tachometer that measures the rotational speed (RPM) of a shaft, fan, or motor using an Infrared (IR) sensor. The system detects light changes from a reflective mark (or interruptions through a slotted disc), counts pulses with a microcontroller, and displays real-time RPM on a screen. Ideal for labs, workshops, and project demonstrations.

Parts Used:

1. Microcontroller: Arduino Uno/Nano (or ESP32 for Bluetooth/IoT)
2. IR Sensor (choose one):
3. Reflective sensor (e.g., TCRT5000 + LM393 board) + reflective tape/white mark, or
4. Slotted/Photointerrupter (encoder-style) with a slotted disc
5. Display: 0.96″ OLED (I²C) or 16×2 LCD
6. Signal Conditioning: Built-in LM393 comparator (common on sensor boards) or Schmitt trigger input
7. Push Buttons/Encoder (Optional): Set pulses-per-revolution (PPR), reset, hold
8. Power Supply: 5 V DC adapter or USB; optional 9 V with regulator / power bank
9. Mounting: Sensor bracket, slotted disc or reflective tape/paint mark
10. Misc.: Wires, connectors, enclosure, fuse