This circuit is from an American publication of the 80's. It makes use of components of the time. However, the circuit is the basis for a modern shield application since the input is TTL.
September 2016 - Mouser Electronics is providing new ultraviolet LEDs VLMU1610 of Vishay suitable...
The frequency of this circuit is approximately 1 Hz. Whenever the output is at low level, the LED...
This circuit triggers a remote doorbell when the phone rings. The circuit is for the 110 V mains...