SunFounder 3in1 Kit
There is a fixed frequency oscillator, which is built with a 555 timer IC. The generated square wave is then fed to the
sensor like a capacitor. However, for the square wave signal, the capacitor has a certain reactance or, for the sake of
argument, a resistor with a pure ohmic resistor (10k resistor on pin 3) to form a voltage divider.
The higher the soil moisture, the higher the capacitance of the sensor. As a result, the square wave has less reactance,
which reduces the voltage on the signal line, and the smaller the value of the analog input through the microcontroller.
Specification
• Operating Voltage: 3.3 ~ 5.5 VDC
• Output Voltage: 0 ~ 3.0VDC
• Operating Current: 5mA
• Interface: PH2.0-3P
• Dimensions: 3.86 x 0.905 inches (L x W)
• Weight: 15g
Example
• 4.4 Measure Soil Moisture (Basic Project)
48 Chapter 1. Components List and Introduction
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