In this a warning device WD1 is in series with SCR1. When the liquid level causes a conductive path between the probes, the SCR conducts sounding WD1. The warning device may be a Sonalert (TM), a lamp or a buzzer.D1 acts as a transient suppressor.
Press SI to reset the circuit.
water level detection for overhead tank
Make a Water Level Indicator at Home ( Hindi / Urdu )