Built your very own parking sensors for ... The ultrasonic sensor, for example, ... Watch the video below to see the system in action and jump to 1:50 to see the circuit and code used for the Arduino.

In this circuit, the infrared emitter IRED1 is modulated by connecting its anode (A) to ~38kHz signal yielded by D9 of the Arduino Uno (TP1) while its cathode (K) to a ~1kHz signal available at D8 of ...

My hardware is slightly different than the example and mine sits at about 2 or 3 and goes up to 14 or 15 with direct touch and about 9 with a piece of tape over it. Found I have plenty of ...

At the heart of the circuit is the OS25B10 transmissive optical sensor with phototransistor output (OC1). Next is the venerable LM393 dual comparator chip (IC1) configured as a simple Schmitt trigger ...