LM393 Slotted Optical Speed Sensor Module, 3.3–5V

This slotted optical speed sensor module utilizes an LM393 comparator to detect pulse counts, motor RPM, and position limits. Operating at 3.3V to 5V with a clean digital TTL output, it connects seamlessly to microcontroller development boards. It is well-suited for robotics hobbyists, STEM learners, and maker projects requiring rotary encoding or object counting.

Optical sensing performance

The module integrates a 5mm slot optical coupler and an LM393 wide-voltage comparator to deliver clean signal waveforms with a drive capability exceeding 15mA. When the optical slot is blocked, the digital output goes high and the onboard state light turns off; when unblocked, the output switches low and the LED lights up.

Interfacing and versatility

The DO output connects directly to a microcontroller IO port for speed and pulse measurement, such as reading motor encoder discs. It can also be paired directly with relays, limit-switch circuits, or active buzzers for alarm functions.

Wiring connections

The board features three operational connections: VCC for 3.3V to 5V power, GND for ground, and DO for the TTL digital switch signal output. The AO pin is not functional on this specific module.

Package contents

The package includes one speed measuring sensor module featuring a compact 3.2 cm x 1.4 cm PCB and an integrated mounting bolt hole for easy installation.