Indian Institute of Technology Hyderabad CONTACTLESS TACHOMETE R Group members: Moruboyina Alekhya Kodi Padmasree D.Hima Varsha

INTRODUCTION  Definition:  An electrical instrument used to measure the speed of a rotating object with out any physical contact.  In general these tachometers can measure through a distance of 1m  Components  Wheel coloured as required  Micro controller(at89c52)  IR sensor  Motor  Battery  LCD screen  Conducting wires

WORKING PRINCIPLE  The main thing in tachometer is counting,which is done by microcontroller.  MICRO CONTROLLER: Micro controller is a type of CPU which is used on the circuits and contains RAM input and output  PARTS OF MICROCONTROLLER

PROXIMITY SENSOR  A sensor which detects some things near by with out any physical contact is called proximity sensor  IR sensor is nothing but an diode in which the diode produces a small current when the light falls on it  These currents are very small to detect so we use operation amplifier to detect the small voltage changes.  Transistor amplifies the current.

Principle of counting

CIRCUIT DIAGRAM

PROGRAM FOR MICROCONTROLLER TO COUNT THE PULSE  First the program is written to set up the counter and stater to be at zero as soon as we start  EA = 1; // be used in in the tachometer  ET0 = 1; //set the Timer/counter 0  TR0 = 1; //Enable Timer/counter 0 to count  TMOD = 0X25; //counter 0 in mode 1 (16 bit counter),  //timer 1 in mode 2 (auto reload from TH1)  TH1 = 0; //start counter from 0  ET1 = 1; //enable timer 1  TR1 = 1; //Enable Timer/counter 1 to count  PT0 = 1; //Setup the priorities of timer 1 and timer 0, a 0 gives a  PT1 = 0; //higher priority.  Storing the counting number and calculating it per min.

EXPLANATION OF CIRCUIT  LCD is connected through some resistors to the ports of the micro controllers.  The LED’s and LCD’s are always connected through the resistor. They are very sensitive to the high voltages(at max 5 volts).  The wire connection P1, which is connected to the output of the sensor, is connected to the pin 3.4 of the microcontroller, this pin has a dual function which is to count incoming pulses and increment a 8, 13, or 16 bit register according to the configuration of the timer T0.

 The idea behind most digital counting device, frequency meters and tachometers, is a micro-controller, used to count the pulses coming from a sensor or any other electronic device. In the case of this tachometer, the counted pulses will come from proximity sensor, which will detect any reflective element passing in front of it, and thus, will give an output pulse for each and every rotation of the shaft.  Those pulses will be fed to the microcontroller and counted. to understand the microcontroller counts pulses and deduce the frequency of those pulses.

ADVANTAGES OF CONTACTLESS TACHOMETER(over traditional)  The current design is an Embedded application which is used to calculate the speed of the motor without the need of tachometer. In this application IR frequencies are used to calculate the speed of the motor.  It gives better performance and reliability.  Light in weight as compared to the conventional tachometer.  Compact in size.  It is portable so we can carry it to large rotating machine to note the r.p.m

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