I design this rpm sensor in a first place to measure rpm of brushless motor. It's works quite well on clear and/or reflective surface at a short distance ( around 1 cm). Stick a black strip on the rotating object. The phototransistor will detect the changes between black and metal/reflective surface.
Output signal : Square signal , max amplitude = 3.5V at Vcc =5V. The frequency of the output signal gives you the RPM.
The design has the footprint of the optical components on both side, allowing to chose the mouting side according to your mechanical requirements. Mount only one pair of optical components.
A C librairie is available to use this sensor with an Arduino.
- Voltage : 5V
- Current : around 50mA