Humidity detector circuit

A circuit for a humidity detector is given . The sensor (humidity detection element) is composed of two sets of thin wires, each of which is very close to each other, about 2mm. When raindrops fall or the air humidity is high, a conductive path is formed between the two sets of wires. The 6V power supply voltage is added to the base of the transistor VT1 through the resistor Rj, causing VT1 to conduct, and the immediate voltage drop causes the thyristor to turn on . Tube vs conduction, the alarm will send out an alarm signal. The alarm can only be stopped by turning off the switch SA. The transistor VT1 is ZN3706 and can be replaced by the domestic model 3DK9B.