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Do you often forget to water your indoor plants? Or perhaps you give them too much attention and over water them?

If you do, then you should make yourself a battery-powered soil moisture monitoring stick. This monitor uses a capacitive soil moisture sensor and a 3.3V Arduino Pro Mini to continuously monitor the soil moisture level and alert you when you’re over or under watering your plants.

Two potentiometers on the board allow you to adjust and set a high and low moisture level setpoint which trigger the flashing of two LEDs to alert you. You can also easily add a buzzer to the circuit if you’d like an audible alarm as well.

You can also push a button to display the current moisture reading and the high and low level setpoints on the built-in OLED display.

With the standard setup here, the unit lasts around 15-20 days on a single charge of the 18650 battery powering it. But, by using two low power techniques, this can be extended to around 50-60 days per charge.

To build one soil moisture monitor, you’ll need:

3.3V Arduino Pro Mini
The 5V Version Can Be Used With A Different Battery & 220Ω LED Resistors

USB Programmer - Buy Here
Capacitive Soil Moisture Sensor
3 x 5mm LEDs (Preferably Different Colours)
10K Resistor
3 x 100Ω Resistors
2 x 10K Trim Pots - Buy Here
Tactile Pushbutton Switch
Slide Power Switch
128x32 I2C OLED Display
Male Header Pins
Female Header Pins
Ribbon Cable - Buy Here
To Power The Monitor

18650 3.7V Lithium Battey
18650 Battery Holder/Charger”

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