Gravity Capacitive Soil Moisture Sensor
Sola 2025-05-21 21:56:31 415 Views2 Replies Hi,
I'm looking at the schematic for the Capacitive Soil Moisture Sensor https://www.dfrobot.com/product-2054.html and trying to understand it, is the any more infirmation on the IC's U1A, U1B, U2 and U3? Many thanks
Hi and many thanks for the info - sorry it took me a while to respond, I didn't get a notification.
U2 looks like a microcontroller so I was wondering if this was being used to produce a higher frequency squarewave, as I understand it the higher the frequency the greater the sensitvity? The rest makes sense, I think :-)
Thanks also for a link to your project, I will take a look…. nice work :-)
Sola U1A and U1B are sections of the LM324 quad op-amp IC. In the sensor circuit, U1A and U1B are configured as comparators or amplifiers to process the analog signal generated by the capacitive sensing element. They help in amplifying the minute voltage changes corresponding to soil moisture variations.
U2 is an NE555 timer IC configured in astable mode to generate a square wave signal. This signal is used to excite the capacitive probe. The frequency of the oscillation changes with the capacitance, which varies based on the soil moisture level.
U3 is a voltage regulator, such as the AMS1117, which ensures a stable voltage supply to the sensor circuit. It allows the sensor to operate safely within a voltage range, typically 3.3V to 5.5V, making it compatible with various microcontrollers.
If you want to make a minimalistic soil moisture sensor, you can see here: https://www.pcbway.com/project/shareproject/Minimalistic_Soil_Moisture_Sensor_324d77fd.html
ahsrab.rifat 
