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Project Title
Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of
appliances through telephone lines. It can be used to switch appliances
from any distance, overcoming the limited range of infrared and radio
remote controls.
The circuit can be used to switch up to nine appliances (corresponding
to the digits 1 through 9 of the telephone key-pad). The DTMF signals
on telephone instrument are used as control signals.
The digit ‘0’ in DTMF mode is used to toggle between the appliance
mode and normal telephone operation mode. Thus the telephone can be
used to switch on or switch off the appliances also while being used for
normal conversation
ABSTRACT
PROJECT BLOCK DIAGRAM
HARDWARE REQUIREMENTS
POWER SUPPLY BLOCK
555 TIMER
RELAY
MT8870 DTMF DECODER
CD4049 INVERTER
CD4013 FLIP FLOP
MCT2E OPTO-ISOLATOR
74LS154
BC547
NPN TRANSISTOR
POWER SUPPLY
230 V AC 50 Hz
5V DC
12V step down transformer
Filter(470µf)
5v RegulatorBridge rectifier
555 TIMERThe 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and multivibrator 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,
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.
Pin Name Purpose
1 GND Ground, low level (0 V)
2 TRIG OUT rises, and interval starts, when this input falls below 1/3 VCC.
3 OUT This output is driven to +VCC or GND.
4 RESET A timing interval may be interrupted by driving this input to GND.
5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).
6 THR The interval ends when the voltage at THR is greater than at CTRL.
7 DIS Open collector output; may discharge a capacitor between intervals.
8 V+, VCC Positive supply voltage is usually between 3 and 15 V.
Internal architecture of 555 timer
CD4049-INVERTER
The CD4049 devices are inverting hex buffers, and feature logic
level conversion using only one supply voltage (VCC)
These devices are intended for use as CMOS to DTL/TTL
converters and can drive directly two DTL/TTL loads
Pin out
FEATURES
CD4049UB Inverting
High Sink Current for Driving 2 TTL Loads
High-To-Low Level Logic Conversion
100% Tested for Quiescent Current at 20V
Maximum Input Current of 1μA at 18V Over
Full Package
Temperature Range; 100nA at 18V and 25oC
5V, 10V and 15V Parametric Ratings
FUNCTIONAL DIAGRAM
DTMF DECODER
This circuit detects the dial tone from a telephone line and decodes
the keypad pressed on the remote telephone.
Two distinct frequency tones make up the DTMF(dual tome
multiple frequency), and hence the name.
The dialer and the telephone exchange communicate one way
through the DTMF communication.
The tone generator and the tone decoder consist of a complete
communication setup. In this project, IC MT8870DE is used to decode the input dial tone
to the dialed numbers.
CONTD..
These digital bits are interfaced to a microcontroller for any
application.
Pulse/dial tone method is used in the modern telephone
communication.
There is a dial tone generator on the caller side and a unique tone
consisting of two audible tone frequency is generated when the
user presses a button.
As an example, 697hz & 1209hz will be generated when key '1' is
being pressed on the phone.
A decoder circuit is present on the receiver side, which decodes the
tone to a digital code.
CD4013 FLIP FLOP
The CD4013B dual D-type flip-flop is a monolithic complementary MOS
(CMOS) integrated circuit has two D-type flip-flops, which you can use
independently
A D-type flip-flop, also called a D-type bistable, is a subsystem with two stable
states. Using appropriate input signals, you can trigger the flip-flop from one
state to the other.
Features:
High-Voltage Type (20V Rating) with Set-Reset Capability
Static Flip-Flop Operation
Medium-Speed Operation - 16 MHz (typ.) Clock Toggle
Rate at 10V
Maximum Input Current of 1μA at 18V Over Full Package
Temperature Range; 100nA at 18V and +25oC
The D-type has four inputs. These are:
Data input: This is connected either to a LOW voltage,
logic 0, or to a HIGH voltage, logic 1
Clock :The clock input is rising-edge triggered, meaning
that it responds only to a sudden change from low to high.
Set input: The SET input is normally held LOW. When it
is pulsed HIGH, the outputs of the bistable are forced
immediately to the SET state.
Reset input: The RESET input is normally held LOW.
When it is pulsed HIGH, the outputs of the bistable are
forced immediately to the RESET state.
Continued ….
Fig:Functional Diagram
OPTO-ISOLATOR
Opto coupler is a 6 pin IC.
It is a combination of 1 LED and a transistor.
when light falls on the Base-Emitter junction then it
switches pin5 goes to zero.
When logic zero is given as input then the light doesn’t
fall on transistor so it doesn’t conduct which gives logic
zero as output.
When logic 1 is given as input then light falls on
transistor so that it conducts, that makes transistor
switched ON and it forms short circuit this makes the
output is logic zero as collector of transistor is
connected to ground.
74LS154
Each of these 4-line-to-16-line decoders utilizes TTL
circuitry to decode four binary-coded inputs into one of
sixteen mutually exclusive outputs when both the strobe
inputs, G1 and G2, are LOW
The demultiplexing function is performed by using the 4
input lines to address the output line, passing data from
one of the strobe inputs with the other strobe input
LOW. When either strobe input is HIGH, all outputs
are HIGH.
These demultiplexers are ideally suited for
implementing high-performance memory decoders. All
inputs are buffered and input clamping diodes are
provided to minimize transmission-line effects and
thereby simplify system design.
FEATURES:
Decodes 4 binary-coded inputs into one of 16 mutually exclusive
outputs
Performs the demultiplexing function by distributing data from one
input line to any one of 16 outputs
Input clamping diodes simplify system design
High fan-out, low-impedance, totem-pole outputs
Typical propagation delay
3 levels of logic - 23 ns
Strobe - 19 ns
Typical power dissipation 45 Mw
BC547
The BC547 transistor is an NPN Epitaxial
Silicon Transistor.
The BC547 transistor is a general-purpose
transistor in small plastic packages.
It is used in general-purpose switching and
amplification BC847/BC547 series 45 V, 100
mA NPN general-purpose transistors.
Whenever base is high, then current starts
flowing through base and emitter and after
that only current will pass from collector to
emitter
BIBILOGRAPHY
www.beyondlogic.org
www.wikipedia.org
www.howstuffworks.com
www.alldatasheets.com
QUERIES ?
THANKYOU
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