This circuit was found in a 90s American publication. The same configuration appears in several places on this site, obtained from different sources. The lamps can be replaced by LEDs.
This circuit produces a loud sound in the speaker when water level reaches the sensor. The power...
May 2016 - It can be obtained from Mouser Electronics new display 1092 from VDC. The new LED...
This Motorola circuit is from 1965. Collector currents must be 7 and 12 A for transistors....