Water Leakage Sensor 01

Using the low voltage conduction principle of the PNP transistor base, the detection pin is short-circuited to ground when there is water. The transistor conduction detection
pin is made of 2.54 pins.
Voltage: 3.3-5V
signal: output high level
device is 0805 package, you can choose device package below 0603 to make the board smaller.
The socket is PH2.0, the detection head is 2.54 pins, and a sponge should be added to the pin to increase sensitivity.
I used a soldering iron high temperature sponge. This sponge is very small when dry, and it expands quickly when it encounters water, greatly increasing the reaction sensitivity.
You can cut the sponge into small squares, insert the detection head into the sponge, and then glue it to the place where it needs to be detected.
This detection circuit can not only output switching quantity, but also output analog quantity according to humidity. There are 4096 levels in total, which is very playable. See video 2 for details.