Soil Moisture Sensor Circuit Using 555. The sensor is composed of a two parallel aluminum plates as in a capacitor. The basic idea of this circuit is that it s charging and discharging c1 through the combination of r1 with r3 c3 r4 c2.
The basic idea of this circuit is that it s charging and discharging c1 through the combination of r1 with r3 c3 r4 c2. An lm7805 voltage regulator is used for limiting the input voltage to 5v. We use it to avoid the electrical current from flowing only within the photon.
Take a look at the 555 datasheet you can see how trig and thrs work to turn the out pin high and low.
Because of the 555 pin the heavily reduced current because of the high resistance flow through the sensor. This humidity sensor circuit uses the 555 integrated circuit timer. The output of this circuit is connected to analog arduino pin a0. Your circuit is a little different to the normal 555 circuit.
