Automatic doorbell using object detection

Automatic doorbell using object detectionGROUP MEMBERSAbhiramiAkhila SebastianAbidha ShanavasJenita MathewsReshma JollyRijoe Chacko MathewOur Guide:Er. Nishant P.R

introductionWe all have a doorbell at our homes. When a visitor comes to our house, he searches for the doorbell switch and then rings it to let us know his presence. If the person who came to our house cannot find the doorbell or else if the person is so short that he cannot reach the doorbell, what can be done? How will it be if we use an automatic doorbell which rings as soon as a person arrives at our place? There are no more hassles. The person who comes to our house need not search for the doorbell and press it any more. If we install this automatic doorbell using object detection circuit, the circuit will automatically sense the presence of the person and it rings the doorbell.Circuit Diagram

CIRCIUT DIAGRAMComponents usedIC LM324IC NE555CAPACITORS: .47F, .001F x 4RESISTORS:12k, 4.7M, 1M x 2, 900, 400k, 300k, 680, 600k, 3.3k x 2, 500k variable, 10k variable, 1k TRANSISTORS: BC 337, BC 327LDRBUZZERRELAY 12VDiode:1N4001LEDULTRASONIC TRANSMITTER AND RECEIVER

Project Description

This circuit helps to ring the door bell automatically if any object or person comes nearer to the door. As a result, the person need not search for the calling bell and ring the bellProject Summary

The circuit operates using a pair of ultrasonic transmitter and receiver modules which are used to detect the person. When the person is detected (the person is in the front door), the doorbell is automatically turned ON.A 555 timer is used to generate a square wave with frequency of 40 kHz at 50% duty cycleThe timer output is fed to a BC337 & BC327 transistor arrangement which provides the power amplification for the input signal. It amplifies the 40kHz signal.The amplified signal at 40khz frequency is emitted through an ultrasonic transmitter.The ultrasonic transmitter operates at a frequency of about 40 Kilo-Hertz. That means it continuously transmits the ultrasonic waves of about 40KHz. The sensitivity of the receiver can be tuned by using the 500K-ohm variable resistor arranged as a pot in the circuit. By tuning this properly, we can achieve the desired results.The receiver in this circuit uses IC LM324 which is internally has four op-amps. Out of the four op-amps, we are using only three of them and leaving the other one unused as it is not much required in our case.The three op-amps are used in cascaded arrangement to provide high gain as well as noise free outputAn opto coupler is used at the output to avoid any interaction between our circuit and the door bell.The output of our circuit is given to a buzzer circuit which acts as a doorbell in our case. The power supply should be moderate such that the range of the transmitter is only about one or two meters.We have provided a power supply using a 9V DC adapter with filtered and regulated output.

Ic lm324The LM324 series are low-cost, quad operational amplifiers with true differential inputs. They have several distinct advantages over standard operational amplifier types in single supply applications. The quad amplifier can operate at supply voltages as low as 3.0 V or as high as 32 V with quiescent currents about onefifth of those associated with the MC1741 (on a per amplifier basis). The common mode input range includes the negative supply, thereby eliminating the necessity for external biasing components in many applications. The output voltage range also includes the negative power supply voltage

Ic ne555 Low turn off time Maximum operating frequency greater than 500khz Timing from microseconds to hours Operates in both astable and monostable modes High output current can source or sink 200ma Adjustable duty cycle TTL compatible Temperature stability of 0.005% perc

AdvantagesEasy installation.Portability.Low Price.Low Power-uses only 9V DC supply.Acts as a burglar alarm during night.Range of detection can be adjusted easily.It is automatic-person need not search for the calling bell and ring the bell.

DisadvantagesLess sensitivity.High noise.May disturb dogs or cats nearby because of the use of ultrasonic.Object is detected only if it is in the range of detection(which is usually one-two meters).

conclusionIn this method we explained the methodology to automatically detect an object in the range of detection using ultrasonicThe circuit consists of low cost components and it is simple in design.