A calling bell or doorbell is a signaling device typically placed near a door. The electric doorbell was invented by Joseph Henry in 1831. The doorbells can be wired or wireless.
This switchless bell project aims to construct a very simple wired door bell that you can place on the door of your house. It rings automatically when anyone enters the proximity of the door, and so the guest does not need a switch to ring the door bell.
The objective of the project is to design a system that can detect the person in front of the door. For this purpose, IR obstacle sensors are used.
Methods and Methodology:
The assembly is very simple and easy to set up. It works on the idea of obstacle sensors. The sensors sense the person/obstacle near the door. An 8051 micro controller will do the job of a brain here. When obstacle is sensed the micro controller will switch on a speaker which generates a melody for a while. Only one sensor is enough to have a working system but more than one sensor will increase the reliability of system significantly.
The implementation of the switchless calling bell is very simple and easy to set up. It works on the idea of obstacle sensors. There will be two sensors mounted on the door, which will give digital output logic high when they sense the obstacle. An 8051 micro controller will do the job of a brain here. When obstacle is sensed the micro controller will switch on a speaker through a triggering mechanism to generate a melody for a while and again switch off, and will be continuously monitoring the sensors. Only one sensor is enough to have a working system but more than one sensor will increase the reliability of system significantly.
Parts of the Systems:
- Sensor: We will use IR proximity sensors, which will give us digital output. So when it detects obstacle it will give logic high signal and interrupt can be sensed.
- Micro controller: We are using micro controller 8051 to implement the overall system. Proximity sensor established on door will be connected to any digital IO pin.
- Buzzer/Bell: We will use a speaker or a buzzer to notice user.
Hardware Block Diagram:
The LM358 operational amplifier is used to make improve precision of sensors.
Programming Language: Embedded C
Sensors: IR Proximity sensors.
Output: Buzzer output on detecting a visitor.
- Switch off the buzzer.
- Get data from sensor.
- If sensor detects an obstacle switch on buzzer to play melody to intimate user.
- Switch off the buzzer.
- Go to step 2