Based on the well-known LM3909, this LED pulser circuit was found in American documentation from the 90's. The power supply is only 1.5 V.
When the light falling on the sensor is cut off, the SCR fires, powering the lamp. Remember that...
When the sensor is wetted by a spray caused by someone falling into a pool or even by a wave...
This traditional TTL anti-clock setting was found in a 1993 American documentation. The circuit...