“Door Bell for Deaf”

Presenters:Srikant Mohanty

Siba Prasad Sahu

Door Bell:A doorbell is a signaling device typically placed near an entry door to a building. When a visitor presses a button the bell rings inside the building, alerting the occupant to the presence of the visitor. Although the first doorbells were mechanical, activated by pulling a cord.But modern doorbells are electric — they are actuated by an electric switch. A precursor to the electric doorbell, specifically a bell that could be rung at a distance via an electric wire. was invented by Joseph Henry around 1831.

[OLD DOOR BELLS]

In most wired systems, a button on the outside next to the door, located around the height of the doorknob, activates a signaling device (usually a chime, bell, or buzzer) inside the building.

BASICS OF DOOR BELL:There are two types of Door bells are there i.e

1.Wired Door-bell

2.Wireless Door Bell.

1.Wired Door-Bell:-

WIRED DOOR BELLS

A doorbell transformer steps down the 120–240-volt AC electrical power to a lower voltage, typically 10–20 volts.

The transformer's other terminal connects to one of three terminals on the signaling device.

Another terminal is connected to a wire that travels to the other terminal on the button.

Pressing the doorbell button, a single-pole, single-throw (SPST) switch. momentarily closes the doorbell circuit. One terminal of this button is wired to a terminal on a transformer.

The flat bars are tuned to two pleasing notes. When the doorbell button is pressed, the first solenoid's plunger strikes one bar, and when the button is released, a spring on the plunger pushes the plunger up, causing it to strike the other bar, creating a two-tone sound ("ding-dong"). The doorbell button contains a built-in radio transmitter powered by a battery.

When the button is pushed, the transmitter sends a radio signal to the receiver unit, which plugs into a wall outlet inside the building. When the radio signal is detected by the receiver, it activates a sound chip, which plays the sound of gongs through a loudspeaker, either a two-note "ding-dong" sound, or a longer chime sequence such as Westminster Quarters . wireless Door-Bell:- To avoid the possibility of nearby wireless doorbells on the same radio frequency interfering with each other, the units can usually be set by the owner to different radio channels.

WIRELESS DOOR-BELLS

If a second doorbell is used, it is wired to the other solenoid, which strikes only one of the bars, to create a different sound. In recent decades, wireless doorbell systems have become popular, which don't require wiring in the walls.

Introduction:-The simple task of answering a doorbell becomes a challenge when a person is deaf or hard of hearing. A doorbell for a deaf person needs to use something other than sound to alert the person of a visitor.

There are a number of options available to help accommodate the need to make a doorbell for a deaf person.

Basically for deaf we can use two types of Door-bells these are

1.Vibration Based Door-bell.

2.Light Based Door-Bells.

3.Radio Door-Bell.

1.Vibration Based Door Bell:-

The Person who are hearing Impaired they can’t hear the voice of the Door bell but they can feel the vibration.

So in order to make them feel and get them know that someone is in the Door we use the Vibration based door bells.

Which gives a little shake to the person when the switch is pressed andGet the deaf person some sense that someone is there in the Door.

The vibration sensor is usually adjustable on a door knock alert system, so the level of vibration that triggers the alert is determined by the person using it.

Light Door-Bell:-Light doorbells, or visual alerting devices, use light to alert a person that someone is at the door.

These doorbells range from a single light connected to the doorbell to a more elaborate system that flashes all the lights in the house.

These doorbells are either activated by a doorbell button or a door knock alert system. With a door knock alert system, when someone knocks on the door a vibration sensor unit detects the vibration caused by the knocking and thus signals a bright light to flash.

LIGHT DOOR-BELL

CIRCUIT DIAGRAM

This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch

can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties.

DESCRIPTION

COMPONENTS USED:-

DIODE 1N4001

BULB 2 NOS.(12V,60mA)

PUSH BUTTON.

DPDT SWITCH.

RESISTOR (22R,10W)

RESITOR(100K)

RESISTOR(47R)

CAPACITOT(47u)

TRANSISTOR(ZTX550)

FUSE(500mA)

BATTERY(12V)

The circuit uses standard 2 wire doorbell cable or loudspeaker wire.

In parallel with the doorbell switch, S1, is a 1N4001 diode and a 12 volt 60mA bulb.

The bulb is optional, it may be useful for anyone who is slow to answer the door, all you need to do is flick a switch inside the house, and the bulb will illuminate a label saying Please Wait inside the doorbell switch or close to it. The double pole double throw switch sends the doorbell supply to the lamp, the 22 ohm resistor is there to reduce current flow, should the doorbell switch, S1 be pressed while the lamp is on..

WORKING:

The resistor needs to be rated 10 watts, the 0.5 Amp fuse protects against short circuits.

When S2 is in the up position (shown as brown contacts), this will illuminate the remote doorbell lamp. When down, (blue contacts) this is the normal position and will illuminate the lamp inside the house.

Switch S1 will then charge the 47u capacitor and operate the transistor which lights the lamp. As a door bell switch is only pressed momentarily, then the charge on the capacitor decays slowly, resulting in the lamp being left on for several seconds.

Continue……

If a longer period is needed then the capacitor may be increased in value.

This is all about the working circuit diagram.

Radio Door-Bell:-It is for someone who is not entirely deaf but can't hear a regular doorbell, a radio doorbell might be the answer. Radio doorbells send out signals that trigger speakers throughout the house or apartment. These speakers then make a loud noise to alert the person that someone is at the door.

Radio Door-Bell

Like Light doorbells and door knock alert systems doorbells, radio doorbells are generally wireless devices. They are also probably the most affordable option of deaf-oriented doorbell.

It is all about the radio door-bell.

Conclusion:Here we got all the types of door-bell systems their working and benefits as well as we got different types of door-bells systems for deaf these are Vibration Based Door-bell , Light Based Door-bell and Radio Door-bell and their workings. It has a future aspects and it can be developed further by using integrated circuits and micro controllers and some intelligent sensor.

mohanty.srikant589@gmail.com

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8093897145

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