automatic room power controller
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Introduction
Electricity conservation assumes a lot of importance in present times, because power is a major powerful factor to global warming. The past few years have recorded the deep surface temperatures ever in global history. Human action is the biggest feature that has led to global warming. It is now up to individuals and organizations to take communal action to slow down and overturn universal warming by using our power resources carefully minimizing fossil fuel use and conserving electricity.
In recent years the energy crisis has become one problem which the whole world must confront. Home power consumption makes up the largest part of energy consumption. Electricity is one thing we waste most. Lights, fans, radios and other appliances are kept on even when no one is using them. It takes less than a second to throw a switch but to some people even this seems a difficult task. They did not-realize that electricity is a national asset and should be conserved and used with care.
In today’s world, there is a continuous need for automatic appliances with the increase in standard of living; there is a sense of urgency for developing circuits that would ease the complexity of life. This project is designed and developed to control the ac OR dc power on/off automatically. Thus we do not have to pay for the electricity we do not use.
How it works….?
The automatic room power controller circuit’s working can be summarized as follows: Two LASER-LDR pair senses the persons moving in and out of the room. Johnson counter 1 &2 counts the persons moving in &out respectively. A group of AND gates determine whether occupants are in the room or not. Relay switches according to the output of AND gates.
The automatic room power controller mainly consist of five sections
Namely,
Biasing section
Sensing section
Clock generation & counting section
Decision section
Switching section
Sensing Section
Working of the Sensing section is as follows:
Two laser diodes and two light dependent resistors (LDRs) are used as sensors at the entry door. This arrangement can be replaced with the combination of IR LEDs and IR sensors or even normal bright LEDs if laser diodes are unavailable. However, Laser diodes with pointed directional light give the circuit better sensitivity and range .Commonly available laser pointers or laser guns can be used as laser diodes.
Light dependent resistors LDR1 and LDR2 are fitted on one pillar (right or left) of the door such that one LDR is inside the door and one is outside the door, as shown in Fig.2.3. Laser diodes LD1 and LD2 are fitted on opposite pillars of the door –one inside and one outside –such that light from diode directly falls on LDR placed on that side (see fig. 2). The LDRs are housed in suitable cabinets to protect from ambient light.
Switching Section
With this arrangement, if any two identical outputs of IC3 and IC4 are high, the output of IC3 and IC4 are high. The high output of AND gates makes transistor T1 conduct via R16.As a result, transistor T2 cut off and relay RL1 de-energises to deactivate the appliance connected to it.
Otherwise, transistor T2 conducts getting base current via resistor R18 and relay RL1 energises to switch on the appliance. At the same time, counters IC3 and IC4 reset via capacitor c3. These can also be reset manually by pressing ‘reset’ switch S1 once.