cellphone based control of electrical equipment
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This document describes a DTMF (Dual Tone Multi-Frequency) based remote control system using a mobile phone. It consists of a DTMF decoder, microcontroller, relays, and appliances. The system allows controlling up to 4 appliances by pressing number keys on the mobile phone. When a key is pressed, the DTMF decoder converts the tones to digital signals for the microcontroller. The microcontroller then activates the corresponding relay to turn the appliance on or off. The system offers remote control of appliances with advantages of quick response, easy operation, and low cost.
cellphone based control of electrical equipment
- 2. CONTENTS Introduction Block diagram DTMF – working Components used Working Software used Advantages 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 – 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 #
- 7. WORKING OF DTMF DECODER
- 10. Transformer & Rectifying unit Headphone –DTMF receiver Receiver – a GSM cellphone
- 11. Mcrocontroller unit DTMF to binary conversion Load driving unit
- 12. Voltage Regulator - 7805 2 pin connector
- 13. Block diagram of Linear Regulated power supply
- 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.
- 17. Pin diagram : Atmel AT89s8253
- 18. LED’s Resistors
- 20. PCB Relay (electromagnetic) Relay driver IC - ULN 2803
- 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
- 25. SOFTWARE USED Mikro C Express PCB
- 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 AC’s 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.