Automatic sprinkler irrigation control circuit

Automatic sprinkler irrigation control circuit

Shown is the automatic sprinkler irrigation control circuit . The circuit is mainly composed of a humidity sensor , detection signal amplifier circuit (transistors VT1,
, rr2, VT3), power circuit (filter capacitor C2, bridge finishing circuit UR, transformer T) and DC motor M, etc.
    In the circuit, the humidity sensor is used to detect the humidity in the soil, and the DC motor M is used to drive the sprinkler irrigation equipment.
    When the sprinkler irrigation equipment has been working for a period of time, the soil humidity reaches conditions suitable for crop growth. At this time, the resistance value of the humidity sensor reflected in the circuit
becomes smaller. At this time, VT1 is turned on and provides the working voltage for the base of VT2. VT2 is also turned on. After vr2 is turned on, it will directly short-circuit the base and
emitter of VT3, so VT3 is cut off, causing the relay coil Kl-l to lose power and disconnect, and drive its normally open contact Kl-2 to return to the normally open state, and
the DC motor will stop when the power is cut off. Work. The sprinkler equipment stopped spraying water.
    When the soil moisture becomes dry, the resistance value between the humidity transmitters increases, causing the base
potential of VT1 to be low. At this time, VT1 is cut off, VT2 is cut off, the base of VT3 is turned on by providing current by &, and the relay coil Kl -l is electrically attracted and drives the normally open contact Kl·2 to close.
The DC motor is powered on and starts working.