Smoke alarm

introduction

• Smoke alarm is a device that automatically detacts or gives the warning in the presence of smoke.

• It is used in in home for safety from fire.

• Also used as theft box.

Material used in smoke alarm

• 555 bistable timer(Ic)• Light dependent resistor(ldr)• Light imiting diode(led)• 2k2 resistor• 10k resistor• 10u capacitor• 4007 doides• Reset switch

• 100 k preset • Buzzer • 9 v battery • Pcb • Soldering material• Soldering iron • Connecting wires • 9 v battery holder

555 bistable timer

• The 555 timer IC is an integrated circuit(chip) used in a variety of timer, pulse generation, and oscillator applications.

• The 555 can be used to provide time delays, as an oscillator, and as a flip flop element. 

• Use as monostable multivibrator, astable multivibrator, analog square wave signal generator, achometer frequency meter and others.

• Basically, 555 timer operate in 2 mode,– Monostable– Astable

Light dependent resistor

• An ldr is a component that has a resistance that changes with the light intensity that falls upon it. They have a resistance that falls with an increase in the light intensity falling upon the device.

• LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops dramatically.

Light emitting doide

• A light emitting diode (LED) is known to be one of the best optoelectronic devices out of the lot. The device is capable of emitting a fairly narrow bandwidth of visible or invisible light when its internal diode junction attains a forward electric current or voltage.

2k2 resistor

• Carbon composition resistor• 1watt as used in many tube

amplifiers(fender, matcheless, mesa boogie, dumble, and many more)due to its superior sonical performance.

10k resistor• 10 k resistor is the most common

electronic component • Used to limit and /or control the

voltage and current.

10u capacitor

• It is used for blocking the circuit.

4007 diodes• A diode is a specialized electronic

component with two electrodes called the anode and the cathode.

• The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction). Thus, the diode can be viewed as an electronic version of a check valve. 

Reset switch

• In den electronics and technology, a reset button is a button that can reset a device.

• The reset button is a button that when clicked, will clear all of the fields.

100 k preset

• A preset resistor also known as a poteintometer is a type of resistor whose resistance is selected by the user. A preset maybe of any range i.e. from 1k to 100k or from 1M to 100M. a preset is used in many circuits where in resistance is required.

buzzer

• A buzzer or beeper is an audio signalling device,[1] which may be mechanical, electromechanical, or piezoelectric.

• Typical uses of buzzers and beepers include alarm devices, timers and confirmation of user input such as a mouse click or keystroke.

9 v battery•  This type is commonly used in

pocket radios, smoke detectors, carbon monoxide detectors, guitar effect units, electro-acoustic guitars and radio-controlled vehicle controllers.

• It’s main function is to pass the power to the device.

• It is the power house

pcb• To hold microchips, capacitors,

transistors, MOSFETs, wiring and more,naturally! PCB means Printed Circuit Board. It's that green (Occasionally other colors) board with all the squiggly lines and technologically looking stuff on it.

Soldering iron

• To heat solder, which is a mixture of metals with a low melting point. The molten metal is allowed to flow around, for example, two pieces of copper. The solder bonds the pieces together when it cools. 

• For electrical work, it typically is used to bond two copper wires together.

Soldering material

• Soldering material is used to solder the components in the pcb like 2k2 can be soldered with the help soldering material.

Connecting wires

• The function of connecting wires is allowing currency to flow through in order to have a complete circuit.

9 v battery holder

• Connects to battery (9 v battery)

Working of theft box• Smoke detectors are one of those amazing

inventions that, because of mass production, cost practically nothing. You can get a smoke detector for as little as $7. And while they cost very little, smoke d etectors save thousands of lives each year. In fact,it is recommended that every home have one smoke detector per floor.

• All smoke detectors consist of two basic parts: a sensor to sense the smoke and a very loud electronic horn to wake people up. Smoke detectors can run off of a 9-volt battery or 120-volt house current.

• In this article, we will examine the two most common types of smoke detectors used today: photoelectric detectors and ionization detectors. And, we'll also take a look inside an ionization detector.

• Occasionally, you will walk into a store and a bell will go off as you cross the threshold. If you look, you will often notice that a photo beam detectoris being used. Near the door on one side of the store is a light (either a white light and a lens or a low-power laser), and on the other side is a photodetector that can "see" the light.

• When you cross the beam of light, you block it. The photodetector senses the lack of light and triggers a bell. You can imagine how this same type of sensor could act as a smoke detector. If it ever got smoky enough in the store to block the light beam sufficiently, the bell would go off. But there are two problems here:

• It's a pretty big smoke detector.• It is not very sensitive.• There would have to be a LOT of smoke

before the alarm would go off -- the smoke would have to be thick enough to completely block out the light. It takes quite a bit of smoke to do that.

• Photoelectric smoke detectors therefore use light in a different way. Inside the smoke detector there is a light and a sensor, but they are positioned at 90-degree angles to one another, like this:In the normal case, the light from the light source on the left shoots straight across and misses the sensor. When smoke enters the chamber, however, the smoke particles scatter the light and some amount of light hits the sensor:The sensor then sets off the horn in the smoke detector.

• Photoelectric detectors are better at sensing smoky fires, such as a smoldering mattress

Thank u…….