1. 1. INTRODUCTION
Remote control for home appliances is an absolute necessity in our fast-paced life. As a result,
much important has been given to this aspect and a range of remote controls are prevalent today.
One of the most common is that which makes use of IR radiations at particular frequencies.
Our product is a Remote Operated Home Appliance or Remote controlled Home appliance. The
circuit is connected to any of the home appliances (lamp, fan, radio, etc) to make the appliance
turn on/off from a TV, VCD, VCR, Air Conditioner or DVD remote control. The circuit can be
activated from up to 10 meters. It is very easy to build and can be assembled on a general-
purpose PCB.
The circuit essentially consists of a transmitter consisting of a 555 IC, the receiver consisting of
an IR module, CD4017 IC, LED‟s to indicate the reception of the IR radiations, otherwise
indicating the ON/OFF state, relay and other components.
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2. 2. PRODUCT DESCRIPTION
2.1. Model Description
Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance
turn on/off from a TV, VCD or DVD remote control. The circuit can be activated from up to 10
meters. The 38 kHz infrared (IR) rays 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. The output
signal is amplified by transistor T1 (BC558). 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.‟
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4. 4. CIRCUIT DESCRIPTION
The product consists of a remote which is the transmitter of the IR radiations and the receiver
which responds to the radiations and switches ON and OFF the appliance.
4.1. TRANSMITTER
The transmitter is basically an astable multivibrator using 555 timer IC which provides a 38 kHz
frequency at its output. The circuit here uses 555 timer IC to avoid fast switching. (This can also
achieved by using a high value capacitor across TSOP sensor.) You can only switch the circuit
after 3 seconds. The design for the circuit is as given below.
4.1.1. Design:
Frequency f = 1.45/ (R1+2R2)C
Required f = 38000Hz
R1 = 1.2k
R2 = 4.7k pot
C = 10 nF
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5. 4.2. 555 TIMER IC:
The 555 Timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation and
oscillator applications. The 555 has three operating modes:
Monostable mode: in this mode, the 555 functions as a "one-shot". Applications include timers,
missing pulse detection, bounce-free switches, touch switches, frequency divider, capacitance
measurement, pulse-width modulation (PWM) etc
Astable - free running mode: the 555 can operate as an oscillator. Uses include LED and lamp
flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position
modulation, etc.
Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not
connected and no capacitor is used. Uses include bounce-free latched switches, etc.
Internal block diagram of 555 IC
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6. 4.3. RECEIVER
Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance
turn on/off from a TV, VCD or DVD remote control. The circuit can be activated from up to 10
meters.
4.4. Circuit Operation:
The 38 kHz infrared rays 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. The output signal is
amplified by T1 (BC558). 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 applianceis„off.‟
The output of IC1 is taken from its pin 2. LED2 connected to pin 2 is used to indicate the „on‟
state of the appliance. Transistor T2 (BC548) connected to pin 2 of IC1 drives relay RL1. Diode
IN4007 (D1) acts as a freewheeling diode. The appliance to be controlled is connected between
the pole of the 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. Result, we get a relay
toggling on each press on the remote.( If a DC 12 volt relay is to be operated, then a regulated
DC 12 volt power supply is used and the circuit voltage should not exceed DC 5 volts). Any
appliance connected to this circuit can be switched ON or OFF.
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7. 4.4. PHOTOMODULE (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.
4.5. CD4017BC IC:
It is a 5 stage divide by 10 Johnson counter with 10 decoded outputs and a carry out bit. The
configuration of this IC permits medium speed operation and assures a hazard-free counting
sequence. The 10/8 decoded outputs are normally in the logical “0” state and go to the logical
“1” state only at their respective time slot. Each decoded output remains high for one full clock
cycle. The carry-out signal completes a full cycle for every 10/8 clock input cycles and is used as
a ripple carry signal to any succeeding stages.
4.6. RELAY ( 5V DC):
Relays are components which allow a low-power circuit to switch a relatively high current on
and off, or to control signals that must be electrically isolated from the controlling circuit itself.
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10. 6. LIST OF COMPONENTS
R1 = 220K
R2 = 330R
R3 = 1K
R4 = 330R
R5 = 47R
C1 = 100uF-16V
C2 = 100nF-63V
C3 = 470uF-16V
D1 = 1N4007
D2 = Red LED
D3 = Green LED
Q1 = BC558
Q2 = BC548
IR = TSOP1738
IC1 = CD4017
RL1 = Relay 5V DC
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11. 7. PCB LAYOUT
7.1 Transmitter
7.2 Receiver
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12. 8. PCB FABRICATION
FABRICATION PROCESS
The materials required for PCB fabrication are copper clad sheet, paint, drilling machine and
ferric chloride solution.
Steps involved in making a PCB:
I. Preparing the layout of the track: The track layout of the electronic circuit may be drawn on a
white paper. The layout should be made in such a way that paths are in each routes. This enables
PCB to be more compact and economical.
II. Transferring the layout to the copper: The layout made on white paper should be redrawn on the
copper clad using paint or nail varnish.
III. Etching: Ferric chloride solution is popularly used etching solution. The ferric chloride powder is
made into a solution using water and kept in a plastic tray. Immerse the markedcopper clad in
this for two hours. Due to reaction, the solution will become weak.The copper in the unmarked
area will be etched out. Take out the etched sheet from the tray and dry.
IV. Drilling: The holes are made using a drilling machine, for component insertion.
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13. 9. SOLDERING PRACTICE
Soldering is the process of joining two or more similar or dissimilar metals by melting another
metal having low melting point. The materials used for soldering practice are solder, flux, knife,
soldering iron, nose pliers.
Soldering procedure:
i. Make a layout of the connections of the components in the circuit. Plug in the chord of the
soldering iron into the mains to get it heated up.
ii. Check the components by using the multimeter. Then clean the component leads using a blade or
knife. Apply a little flux on the leads. Take a little solder on the soldering iron and apply the
molten solder on the leads.
iii. Mount the components on the PCB by bending the leads of the components using nose plier or
tweezer.
iv. Apply flux on the joints and solder the joints. Soldering must be done in minimum time to avoid
dry soldering and heating up of the components.
v. Wash the residues using water and brush.
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14. 10. TESTING
After soldering the components on to the PCB, the boards are thoroughly cleaned for removing
any residual flux and wire leads. All the components are checked for their values and proper
orientation if applicable. Before ICs are inserted into the sockets, power is applied to the board
and voltages are measured at the IC power points. Other DC voltages are also checked if
possible. Then power is removed from the board, and ICs are inserted into the sockets, checking
the proper orientation. Power is again applied to the board expected voltages and signals are
monitored.
The supply voltages are monitored and verified. Working is tested by aiming the IR beam from
the transmitter to the IR module of the receiver and observing the lighting of the LEDs in the
receiver.
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15. 11. APPLICATIONS
A remote controlled device primarily saves a lot of time and energy. Its significance in today‟s
world is immense when people don‟t have to unnecessarily waste their time in operating the
appliances by being near to the appliance. They can operate it while they‟re engrossed in
whatever task they‟re doing and don‟t have to bother leaving it in between.
The remote control can extend up to a long distance depending on the frequency used and the
efficiency of the circuit. It is an advantage that it can be operated from distances.
It can be used in the case of a number of devices and applications such as TV, VCR, camera, CD
speller, radio, lamp, fan, music system or even tasks such as simply opening a door.
A single remote control can be made to operate at different frequencies, each corresponding to a
particular task to be performed by the appliance, for example television. This is a further
application where a compact device can perform multiple operations.
Tediousness of operating the appliance in its close proximity is done away with. The circuit has
the advantages that it can be easily implemented using easily available and low cost components.
The maintenance is also easy.
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16. 12. CONCLUSION
The product to demonstrate the remote controlled operation of home appliances has been
successfully implemented and favorable results have been obtained. This is a commercially
viable product and its application is widespread these days with almost all home appliances.
Since IR radiations are made use of here, each task can be designed to be performed at different
frequencies, each specific to a particular task. As a result of which several operations can be
performed on a single appliance, as in the case of television. The product finds great scope
futuristically, as part of an environment where man restricts his motion and performs his day-to-
day activities on a remote controlled basis.
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