Suggested by a 90s EDN, this circuit supports almost any LED as a source and a phototransistor as a detector. The circuit operates with a PLL 567 at a frequency of around 40 kHz.
This circuit was obtained from a Linear Technology manual from the 1990s. The sensor is of the...
This circuit is from a PE Hobbyst Handbook from 1991. The integrated circuit is a common 555 and...
This traditional circuit with a neon lamp is a flip-flop that draws which of the two lamps will...