As stated, the circuity can be used to send calibrated pulses to a microcontroller-based tacho meter or similar circuit/device ... So an encoder disc (with a proper encoder resolution) can be placed ...

Here is one simple circuit of a general-purpose white LED security light with Passive Infrared (PIR) Motion sensing mechanism. At the heart of the circuit is a PIR sensor module SB0061. SB0061 is a ...

Inspired by printed circuit boards, the building block of all electronics, a Dutch designer has created an LED-based light installation ... With help from a sensor, the composition also "protects ...