When the probe is inserted into the soil, if the soil is dry, the resistance at the two poles of the probe is very high, and the base of V1 is at the low level V1, and the LED1, LED2 and LED3 are in the off state. When the soil humidity increases gradually, the resistance at the two poles of the probe gradually decreases, and V1 begins to conduct. After the current is limited by resistor R1, the LED 1 is lit. At this time, because the circuit of LED 2 is connected with diode VD1, it needs to be driven by higher voltage. Similarly, LED3 is also connected in series. Only with the humidity gradually increasing, the number of LED lights can light up more.

Specifications:

Product name: soil moisture detector
Product size: 26*48MM
Working voltage: DC5V

Package Include:

1 x Electronic Kit

(The delivery is in parts, which need to be assembled by the buyer. )