27-04-2011, 12:15 PM
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ABSTRACT
This project aims to control the switches in a room and regulate the speed of a fan from your couch or bed. The circuit can be connected to any switch so as to turn it on or off from anywhere in the room.The main advantage is that an ordinary TV remote,which is available in most households, is sufficient for this application. The speed of a fan can also be controlled using the TV remote. The aim of this circuit is to make life more convenient for the disabled, for the senior citizens and also the everyday user.
The 38 kHz infrared (IR) rays generated by the remote control are received by IR receiver module TSOP1738 of the circuit. Additional circuitry is used to decode these signals and to switch a device on or off. The fan speed can also be changed in subsequent steps and can be eventually switched off.
1. INTRODUCTION
1.1 AIM
To create a reliable system to switch the electrical appliances in a room on/off and also enable to control the speed of a fan using an ordinary TV remote control.
1.2 DESCRIPTION
Switching appliances on or off and the regulation of the speed of a fan are the two common things an ordinary person has to do in the day to day usage of electrical appliances in a room or an office. Our project aims at enabling the user to do these things using a single TV remote, which is available in almost every home these days. We have accomplished the basic purpose of switching a light and regulating a fan, a concept which can be extended to any number of devices. It provides a system that is simple to understand and also to operate, a system that would be cheap and affordable, durable, reliable and easy to maintain. It adds more comfort to everyday living by removing the inconvenience of having to move around to operate a fan regulator. We seek to develop a system that is cost effective while not undermining the need for efficient working. We also acknowledge that our concept of an e-room can be completely accomplished only when we will be able control the doors, windows etc. using the same remote.
1.3 MOTIVATION
We believe that electronics aims at improving the comforts of life and the prospect of regulating fan speed and switching on or off a light right from our bed or couch is very appealing. This will also be very helpful for handicapped people, in hospitals, for senior citizens, in offices and in large halls.
1.4 AREA OF PROJECT
Consumer Electronics
1.5 SIGNIFICANCE
1) Ease of operation
2) Low cost
3) No requirement of coding
4) Reliable
5) Simple design
6) High operating range
1.6 COMPONENTS REQUIRED
Switch – TSOP1738, CD4017, BC548, BC558, Resistors, Capacitors, LEDs, Diodes (1N4007), Batteries, Relay.
Fan Regulator – TSOP1738, CD4017, NE555, Opto-coupler - MCT2E, Opto-isolator – MOC3021, Resistors, Capacitors, Diodes, Zener diode (5.1 V), BC548, Voltage Regulator (LM7809)
2. SWITCH
2.1 BLOCK DIAGRAM
2.2 CIRCUIT DIAGRAM
2.3. PRINCIPLE AND WORKING
IR RECEIVER MODULE (TSOP1738)
The TSOP17XX series are miniaturized receivers for infrared remote control systems. PIN diode and preamplifier are assembled on lead frame, the epoxy package is designed as IR filter. The demodulated output signal can directly be decoded by a microprocessor. TSOP17XX is the standard IR remote control receiver series, supporting all major transmission codes. We chose TSOP1738 because major companies like Samsung, LG, BPL, Sony etc. follow remote protocols such as NEC, SIRC which uses the 38 kHz frequency to send their remote signals.
These infrared (IR) modulated signals generated by the remote control are received by IR receiver module TSOP1738 of the circuit. Pin 1 of TSOP1738 is connected to ground, pin 2 is connected to the power supply through resistor R5 and the output is taken from pin 3.
INVERTING AMPLIFIER
The output signal is amplified by transistor T1 (BC558). This amplifier is in inverted configuration in order to convert the output from an active low device TSOP1738 into an active high signal.
RC SMOOTHENING FILTER
The output of the inverting amplifier in the form of a sequence of square pulses is then smoothened out by the low pass filter formed by C1 (0.1u) and R2 (220k).
DECADE COUNTER (CD 4017BC)
The CD4017BC is a 5-stage divide-by-10 Johnson counter with 10 decoded outputs and a carry out bit. The configuration of the CD4017BC and permits medium speed operation and assures a hazard free counting sequence. The 10 decoded outputs are normally in the logical “0” state and goto the logical “1” state only at their respective time slot. Each decoded output remains high for 1 full clock cycle. The carry-out signal completes a full cycle for every 10 clock input cycles and is used as a ripple carry signal to any succeeding stages.
The amplified signal is fed to clock pin 14 of decade counter IC CD4017 (IC1). Pin 8 of IC1 is grounded, pin 16 is connected to Vcc and pin 3 is connected to LED1 (red), which glows to indicate that the appliance is ‘off.’ The pin 3 is the Q0, which is the first state of the counter outputs which is at a high state even before a clock signal is given. As the first clock signal is given Q0 turns low as Q1 turns high. The output is taken from pin 2. LED2 (green) connected to pin 2 is used to indicate the ‘on’ state of the appliance. The next clock to the CD 4017 resets the IC as the next high state at Q2 (pin 4) is connected to the reset pin (pin 15).
RELAY DRIVER (BC 548)
Transistor T2 (BC548) connected to pin 2 of IC1 drives relay RL1. A driver is needed because the relay needs a high current to energize to the ON state. Diode 1N4007 (D1) acts as a freewheeling diode that protects the circuit from inductive sparks that maybe produced during turning on or off or during transient peaks.
RELAY
We use an SPDT relay that switches between open and closed states. It has a single pole and dual throw. The appliance to be controlled is connected between the pole ofthe relay and neutral terminal of mains. It gets connected to live terminal of AC mains via normally opened (N/O) contact when the relay energizes. If you want to operate a DC 12 V relay then use a regulated DC 12 V power supply but the circuit voltage should not exceed more than DC 5 V.
