12-11-2012, 02:05 PM
DC MOTOR SPEED CONTROL USING SCR BY REMOTE
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INTRODUCTION
WIRELESS SPEED CONTROL USING RF
This system for controlling the speed of vehicle near important areas like school colleges or where speed should be a limit to avoid unwanted accidents an automatic system where human intervention is minimized by using identification system which is very much useful for many applications or purpose system helps the user to identify the acess to the required areas through RF. We thought of making a project where wireless RF- linkage between a certain can be used for determination of the access to the area Radio Frequency Identification (RFID) systems use radio frequency to identify, locate and track vehicle. Passive RFID systems are composed of three components – an interrogator (reader), a passive tag, and a host computer. The tag is composed of an antenna coil and a silicon chip that includes basic modulation circuitry and non-volatile memory. The tag is energized by a time-varying electromagnetic radio frequency (RF) wave that is transmitted by the reader. This RF signal is called a carrier signal. When the RF field passes through an antenna coil, there is an AC voltage generated across the coil. This voltage is rectified to supply power to the tag information stored in the tag is transmitted back to the reader which is nothing but the car . This is often called backscattering. By detecting the backscattering signal, the information stored in the tag can be fully identified
POWER SUPPLY
TIMER CIRCUIT:
Trigger: - The output of the timer depends on the amplitude of external trigger pulse applied to this pin. The output is low if the voltage at this pin is greater than 2/3vcc. When the negative going pulse of amplitude greater than 1/3vcc is applied to this pin output goes high.
Output:
There are two ways a load can be connected at output terminal either between pin 3 & pin 1 or pin 3 & pin 8. When output is low the load current passes to a load connected between pin 3 & +Vcc in to a output terminal and is called link current. Current through the grounded load is zero when o/p is low. So load connected between pin 3 & pin 8 which called normally on load & the load connected between the pin 3 & ground is called normally off load. When the output is high current through the load connected between pin 3 &Vcc is zero. The output terminal supplies current through the normally of load. This current is called source current. The minimum value of source & sink current is 200MA.
RF ENCODER
A logic circuit that produces coded binary outputs from encoded inputs. This uses ST12CODEC IC for encoding the data which is transmitted by microcontroller. The encoder converts the parallel data which has been sent from microcontroller to serial form and sends it to RF Transmitter. It consists of the necessary data of the TRAIN. The ST12 CODEC is a single chip telemetry device, which may be an encoder or a decoder. When combined with a Radio transmitter / receiver it may be used to provide encryption standard for data communication system The ST12 CODEC performs all the necessary data manipulation and encryption for an optimum range reliable radio link while providing a simple user interface.
Transmitter and receiver use same IC ST 12 CODEC in RF encoder mode for serial communication. This IC is capable of transmitting 13 bits containing 1 start pulse, 4 bit address bit and 8 bit data. The transmitted information is sent by RF with 315 MHZ RF transmitter. ST12CODEC works on 5v, which is regulated with a low current voltage regulator chip LM7805.
RF RECEIVER
It is enhanced single chip ST433 IC which receives the 433.92 MHz transmitted signal, transmitted by RF transmitter. It uses ASK (Amplitude Shift Keying) conventional heterodyne receiver IC for remote wireless applications.
RF DECODER
A logic circuit that used to decode coded binary word. This uses ST12 CODEC IC for decoding the data which is transmitted by ST433 IC. The decoder converts the serial data which has been sent from RF receiver to parallel form and sends it to microcontroller. The coded data decoded by this block is given to computer via micro controller and RS 232.
MICROCONTROLLER(IC 89C52)
This is the most important block of the entire system. The microcontroller works at crystal frequency of 11.0592 MHz It receives the parallel data from ST12 CODEC IC and compare it with the program code which already stored in it and identifies that weather user has necessary balance or not. If the balance is not enough to pay amount then it sends signal to Relay Driver to activate the camera and if the balance is equals the amount then it gives signal to MAX-232 to activate the computer to store the necessary information in it .This microcontroller has the baud rate 9600 bits/sec.
The 89c52 is a low power, high performance CMOS8 bit micro computer with 8k bytes of flash programmable and erasable read only memory (PEROM).The device is manufactured using Atmel’s high density nonvolatile memory technology and it is compatible with the industry standard 80C51 and 80c52 instruction set and pin out. The on chip Flash allows the program memory to be reprogrammed in system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with flash on a monolithic chip, the Atmel’s AT89C52 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.
POWER SUPPLY
The performance of the master box depends on the proper functioning of the power supply unit. The power supply converts not only A.C into D.C, but also provides output voltage of 5V, 1 amp. The essential components of the power supply are Transformer, four diodes which forms bridge rectifier, capacitor which work as a filter and positive voltage regulator IC 7805. It provides 5v to each block of the transmitter.
The performance of the master box depends on the proper functioning of the power supply unit. The power supply converts not only A.C into D.C, but also provides o/p voltage of 5volts, 1 amp. The essential components of the power supply are:
TRANSFORMER
As name suggests it transforms the voltage level from one level to another. Transformer used is the step down transformer to step 230 v to +5v. It provides isolation too from the mains.
RECTIFIER:
The rectifier is used to convert A.C to D.C voltage. The design that we have carried out is of the full wave rectifier, using 1N4001 diodes.
FILTER:
A filter circuit is a device, which removes ac component of rectified output but allows the dc component to reach the load. The filter used is a simple capacitor of 100µf /25v.