Plan A: Variable Frequency Oscillators

Plan A: Variable Frequency Oscillators

Soil Moisture Sensor Project

Plan A: Variable frequency oscillators

Having rejected methods that were probably inaccurate (because they ran on a low frequency) or were too expensive, I decided to design something from scratch that would use a high frequency to measure the changes in capacitance caused by changes in soil moisture levels. How hard could that be?

So I looked for techniques or devices that used capacitors whose value can be varied. This has been done before and is not hard to do. Variable capacitors have been used to tune radio circuits.

It was this idea of tuning a radio circuit that got me thinking: If a variable capacitor can be used to tune the radio circuit, it meant that a change in the variable capacitor would change the frequency of the radio circuit output….. And if I can measure the change in the frequency of the output, then I can detect changes in soil moisture.