Greenhouse soil temperature detector circuit

Circuit working principle: The soil moisture monitor circuit is composed of an astable multivibrator
, a power supply circuit, a humidity detection circuit, an electronic switch circuit and an LED indication circuit
.
  The astable multivibrator circuit
consists of the oscillation circuit Ic, resistor S and capacitor C1; the power circuit consists of battery GB, power switch S, diode VD, and filter
capacitors CZ and C3; the humidity detection circuit consists of detection electrode A, B, potential RP and
resistor R4; the electronic switch control circuit consists of the electronic switch integrated circuit IC2
(CD4066:S.-S4) and resistors R2 and R3; the indication circuit consists of the operational amplifier
IC3 and the light-emitting diode LED. , LEDz and resistors Rs, R6. RP is used to adjust
the accuracy of detection and indication.