This is a soil moisture sensor that can be used for pot plants or in the garden with a serial interface for logging data to a computer.
Main Components
Micro-controller ATMEGA8
Crystal 3.6864 MHz
Serial interface MAX232
Moisture Sensor Interface 74HC4060
Moisture Sensor 1 meter of 300 ohm ladder line
The principal behind it is that moisture has a high dielectric constant so if you place two insulated electrodes in the soil you can measure the capacitance between them to determine the amount of moisture in the soil. The trick is finding a good means of building insulated electrodes.
(Click To Enlarge)
Testing has shown that there is some interference with this sensor design, possibly through being grounded through the serial connection to the computer. Will have to do more research to see if this sensor will work effectively with wireless communications that provide isolation from the computer.
Each sensor will have to be individually calibrated, due to the huge variation in soils and conditions.
Main Components
Micro-controller ATMEGA8
Crystal 3.6864 MHz
Serial interface MAX232
Moisture Sensor Interface 74HC4060
Moisture Sensor 1 meter of 300 ohm ladder line
The principal behind it is that moisture has a high dielectric constant so if you place two insulated electrodes in the soil you can measure the capacitance between them to determine the amount of moisture in the soil. The trick is finding a good means of building insulated electrodes.
(Click To Enlarge)
Testing has shown that there is some interference with this sensor design, possibly through being grounded through the serial connection to the computer. Will have to do more research to see if this sensor will work effectively with wireless communications that provide isolation from the computer.
Each sensor will have to be individually calibrated, due to the huge variation in soils and conditions.
