Hall Effect Sensor A3144 or and then it reads that

and then it reads that resistance to get the moisture level

and many other cooling and circulation systems

2 x 4 x 5mm

or slave and slave mode

1" spacing - fits great into a breadboard

Hall Effect Sensor A3144 or and then it reads thatA Hall effect latch works like a switch. It will latch on when the magnet is near the sensor (south pole). It will turn off if the opposite magnet pole (north pole) is applied. It can be used for counting rpm of rotating shaft or fan by putting 2 magnets with opposite poles after each others. Features 3. 5V to 24V DC operation voltage Low current consumption Temperature compensation Wide operating voltage range Open Collector pre driver 50mA maximum