18-06-2012, 03:19 PM
STAIRCASE LIGHT WITH AUTO SWITCH OFF
STAIRCASE LIGHT WITH AUTO SWITCH OFF.docx (Size: 1.4 MB / Downloads: 133)
INTRODUCTION
Advancements in the technology and the facilities lead to the change in the life style and in return lead to the loss of many valuable things like power, energy etc…Electronics is fast growing field exploring new horizon in each and every moment. Electronics devices in recent years have found wide spread application in various field of Science and Engineering.
We are all familiar with the electrical wiring arrangement that connects an electrical bulb with two switches one at the bottom of a staircase and the other at the top……
We present our project STAIRCASE LIGHT WITH AUTO SWITCH OFF is an ELECTRONICS-CUM-ELECTRICAL arrangement to get a similar facility as provided by the hard- wired electrical system, but you need to operate the switch only once. Also power is saved.
BLOCK DIAGRAM DESCRIPTION
• DEBOUNCING CIRCUIT:
Electrical contacts in mechanical pushbutton switches often make and break contact several times when the button is first pushed. A debouncing circuit removes the resulting ripple signal, and provides a clean transition at its output.
• IC4011:
Only one switch is active at a time and this is given as input to NAND gates . Output from the NAND gate is given to the diode IN4001. Output is obtained as per the Truth Table of 4011 is shown below.
• MONOSTABLE MULTIVIBRATOR USING 555 TIMER IC:
Trigger from the AstableMultivibrator is given to the Mono-stable Multivibrator, output from it is square wave of 40 second positive pulse ( ie; positive pulse duration of 40 second- for lighting the bulb).Output of the multivibrator is given to the transistor
• TRANSISTOR:
The Transistor is solid state devices, whose operation depends upon the flow of electric charge carriers within the solids.Transistor 2N222 is used here.For positive pulse, transistor is ON- allows energizing of the Relay, at that particular duration bulb is ON (for 40 second duration).For the negative pulse, transistor is OFF- allows de-energized of the Relay, bulb is OFF for the particular duration.
CIRCUIT DIAGRAM DESCRIPTION
The HCF4011B is a monolithic integrated circuit fabricated in Metal Oxide Semiconductor technology available in DIP and SOP packages.
The HCF4011B QUAD 2 INPUT NAND GATE provides the system designer with direct implementation of the NAND function andSupplement the existing family of CMOS gates. All inputs and outputs are buffered.
Figure (b) shows the truth table for a NAND gate. It shows the output voltage (voltage between F and ground) with different input states.
Because there are only two voltages for every pin, we call them states, with logic zero when the voltage is zero, and logic one when the voltage on the pin is the same as the supplyvoltage.