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Temperature and humidity inside the fridge, door-open by tilt, on a rechargeable 18650 cell. From $58 in parts.

PIR motion alert that stays quiet in daylight, using an ambient light sensor. Powered over USB-C. From $33 in parts.

Reads soil moisture and turns a valve lever with a micro servo when the pot is dry. The decision runs on the device. From $39 in parts.

Four capacitive probes, one per bed, on a rechargeable 18650 cell. Readings every ten minutes. From $54 in parts.

Light, humidity and temperature on the windowsill, so you know when the orchids need shade or misting. From $49 in parts.

An accelerometer on the compressor housing tracks vibration and flags a drifting trend, an early sign of bearing wear. About $42 in parts.

A tilt sensor on the door panel reports open or closed, and nudges you when it's left open after dark. About $46 in parts.

A waterproof probe inside the cold room logs temperature and alerts when it leaves the safe range. About $39 in parts.