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water sensor circuit or rain alarm circuit: This diagram shows a device used for water detection, when the probes come in contact with water, the alarm sounds. It consists of only 5 components that are easily available in the market. The IC CD4047 is CMOS-based, so pay attention to the static while installing it. Probes can be any two metal surfaces. It is best to install the screws on the edges of the PCB board, this way you get a rack that holds the entire device above water and you can use any two screws as probes. Setting the alarm is to touch the probes by hand or place the probes of the device in the water and adjust the P1 potentiometer until you get a satisfactory sound from the piezo speaker.
As mentioned earlier there are 14 pins on the IC interface with every pin used for a specific purpose. The given below table shows the pin description of each pin. It is a CMOS very Low Power monostable/stable multi-vibrator mainly used for converting DC current signal to AC signal.(Water Detection Alarm Device)
| Pin# | Pin Name | Pin Description |
|---|---|---|
| 1 |
C
|
Connected to an external capacitor |
| 2 |
R
|
Connected to an external resistor |
| 3 |
R-C Common
|
Common pin for establishing a connection with resistor and capacitor |
| 4 | A stable’ | Must be kept low when used in a-stable mode |
| 5 | A stable | Must be kept high when used in a stable mode |
| 6 | -Trigger | High to Low transition will be given to this pin when used in Mono-stable mode |
| 7 | Vss | Ground Pin |
| 8 | +Trigger | Low to high transition will be given to this pin when used in Mono-stable mode |
| 9 | EXT Reset | External reset triggers when a high pulse is provided to this pin, resetting the output Q to low and Q’ to high |
| 10 | Q | Generates high output |
| 11 | Q’ | It is an inverse output of pin 10, producing a low output |
| 12 | Re-trigger | This pin is used in Mono-stable mode for simultaneously re-triggering +trigger and –trigger pin |
| 13 | Osc Out |
Generate oscillated output
|
| 14 | Vdd | Voltage supply pin |