Rain Alert System

a project made with bipolar junction transistor (BJT)

Rain Alert System is a simple but very useful project that detects Rain (Rain Water) and automatically triggers an alarm or buzzer.

Project Created: Semester of Fall 2019

Project Contributors:
- Md. Muzakker Hossain
- Ashiqur Rahaman Ridoy
- Shah-ul-Jasun

Introduction

Water is a basic need in every one’s life. Saving water and proper usage of water is very important. This project will give the alarm when there is rain, so that we can make some actions for rain water harvesting and also save the rain water for using it later.

With the help of saving this rain water through rain water harvesting, we can increase the levels of underground water by using underwater recharge technique. This can be used in the irrigation field, home automation, communication, automobiles et cetera and can be constructed at a very low cost.

Goal of this Project

The main goal of our project is to make a circuit that can produce an amplified alert whenever it comes in contact with rain water. To do the amplification we are going to use two n-p-n bipolar junction transistors since BJT has a characteristics of giving output of amplified current.

Components Required

  1. AC/DC Power Source
  2. Resistor - 1pc (10k)
  3. BC829 Transistor - 2pcs
  4. Probe Sensor
  5. Capacitor – 1pcs (10uF)
  6. Connecting Wires
  7. LED

Circuit Diagram

Circuit Diagram of the Project

Operating Principle

We will see the working of the simple Rain Sensor Alarm Circuit Project. When rain falls on the sensor, the aluminum wires on the Sensor Board will start conducting and close the path between the supply and base of the transistor Q1. As a result, the Transistor Q1 will turn ON, when the transistor Q1 is saturated and the current at collector region will be amplified and the emitter current will be equal to the sum of base current and collector current (IE = IC + IB), the capacitor C1 will be shorted and will make the transistor Q2 to be turned ON. C1 will get charged by the resistor R1.
When the Transistor Q2 reaches the saturation mode, the output current will be amplified at collector region and it will be more amplified because of previous transistor’s emitter current, this will turn ON the buzzer and the alarm is activated. Because of the resistor R1 and capacitor C1, when the capacitor is completely charged, the transistor Q2 will get in to cut – off mode after sometime.
When there is no rain, the aluminum wire on the sensor will not conduct as they do not have any conduction path (open circuit). As a result, the sensor cannot trigger the transistors and there will be no alarm.

Simulation & Measurement

Advantages

  1. It is cost efficient since it switches off the irrigation system when it rains. This saves money by cutting of bills on electricity consumption.
  2. It extends life of rain sensor based system such as copper irrigation system by running them only when it necessary.
  3. Operating principle is very easy.
  4. It consumes less power of operation.
  5. Installation of rain sensor based system are very much simple.
  6. Individual rain sensor costs very less.

Disadvantages

  1. The rain sensor based system functions when water falls on the sensor directly.
  2. The cost of overall system increases as additional components are needed along with rain sensor.
  3. In order to avoid false detection of rain, it requires rain sensors to take decision after a few minutes.

Conclusion

The rain water detection alert system will be useful in both domestic and industrial applications. It alerts the user of the presence of rain when it is just about to rain as even the minutest droplets of water triggers it ‘ON’, thereby giving the user ample time to retrieve possession and preventing them from being drenched by rain water. This time here in referred to as recovery time is the basis for this design. The device when properly placed to receive the first set of droplets of rain water can save the user from damaging possessions that were being sun-dried prevent from entering homes, offices and sailor to mention a few. All this can be done by this simple circuit that has low pricing which is affordable for any people including the marginal people.