[2024]Digital Global Overview Report 2024 Meltwater.pdf
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cellphone based control of electrical equipment
1.
2. CONTENTS
ďź Introduction
ďź Block diagram
ďź DTMF â working
ďź Components used
ďź Working
ďź Software used
ďź Advantages
ďź Applications
3. INTRODUCTION
⢠What had been thought impossible at one time was achieved by
man.
⢠As technology advanced man was able to control everything from
one place.
⢠Controlling electrical appliances with mobile is one of the examples.
⢠This makes the use of DTMF(Dual Tone Multi Frequency) technique.
⢠The DTMF Decoder circuit is made using M8870 Decoder IC.
⢠Just connect your cell phone headset (headphone) jack to the
mobile phone and then mobile control electrical appliances and
electrical equipment via DTMF key pad of your cell phone.
6. DTMF keypad frequencies
DUAL TONE â every button on keypad is characterised
by two different tones
MULTI FREQ.- because it use a mixture of two pure tone
(pure sine wave) sounds
Hz 1209 1336 1477
697 1 2 3
770 4 5 6
852 7 8 9
941 * 0 #
14. Inside voltage regulator
⢠employs a pass element serving as a variable resistor
which forms a voltage divider with the load.
⢠The pass element can be a transistor placed in
between the unregulated dc voltage and the desired
regulated dc output.
21. Pin diagram : ULN2803
Darlington pair of
transistors
22. Darlington pair of transistors
Very high gain
of the order
10,000 to 100,000
23. WORKING
⢠The first step is to call the reciever phone.
⢠Next we press the required digit on keypad of
sender phone to give an input.
⢠DTMF decoder converts the dual tone. frequency
into a digital signal- 4 bit binary.
⢠Output from decoder becomes the input to the
microcontroller via port 1.
⢠Processing of the digital signal takes place and an
input is generated for relay driving IC-uln2803.
24. WORKING
⢠The driving IC uln 2803 is actually a router which
controls the operation of relays and susequently
the appliances.
⢠Each appliance has a different relay unit
controlling its on-off operation.
⢠In this project we control 4 appliances as:
⢠Key 1,2 : appliance 1 ON & OFF respectively
Key 3,4 : appliance 2 ON & OFF respectively
Key 5,6 : appliance 3 ON & OFF respectively
Key 7,8 : appliance 4 ON & OFF respectively
Key 9 : all appliances gets ON
Key 0 : all appliances gets OFF
26. APPLICATIONS
⢠This system can be used in industrial applications.
⢠This system can be employed in houses ,where people
often forget to switch off electrical appliances
⢠This system can be used to control ACâs to set the room
temperature
when we are outside
⢠We can extend this circuit to control many electrical
devices with some modifications using 4 x16 decoder IC.
27. ADVANTAGES
⢠Quick response is achieved.
⢠Construction is easy.
⢠Easy to maintain and repair.
⢠Comparatively the operation cost is less.
⢠Design is efficient and low cost.
⢠Power consumption is low.
⢠Controlling electrical devices wirelessly
⢠Saves electricity (when we forget to switch off and go out).
⢠We can control appliances from any place round the globe.
⢠No coding is required.