water-diviner

This little unit may be used to give an audible alarm when, for instance, a washing machine hose has burst, or when it starts to rain so you can get the washing in, or it can call you to the bathroom to turn the bathwater off. No doubt you will be able to think of some more uses. The circuit may be powered from a 9 V battery which, since the current consumption is very low, will last for at least a year. After a year it should be replaced because it will then become unreliable owing to its self-discharge. Basically, the unit consists of a sensor, an R-S bistable, an oscillator, and a N1 ...N4 = IC1 = 4093 85460 7-34 water-diviner elektor july/august 1985 driver stage for the alarm buzzer. The sensor consists of a waste piece of wiring board, about 40 x 20 mm. Connect all odd and all even tracks together with wire links, that is, 1 to 3 to 5, and 2 to 4 to 6. Tin the tracks to protect them against corrosion. When the board is dry, the resistance between the two sets of tracks is ...