MICROCNTROLLRS MECH ENGR
MICROCNTROLLRS MECH ENGR EMCH 367
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This 7 page Class Notes was uploaded by Garry Goyette on Monday October 26, 2015. The Class Notes belongs to EMCH 367 at University of South Carolina - Columbia taught by Staff in Fall. Since its upload, it has received 23 views. For similar materials see /class/229638/emch-367-university-of-south-carolina-columbia in Mechanical Engineering at University of South Carolina - Columbia.
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Date Created: 10/26/15
Functional Module Report EmitterDetector Alexander Kloth Edited by Brian Wiggins USER MANUAL FOR EMITTER DETECTOR FUNCTIONAL MODULE emitterdetectordoc l 3 12005 Functional Module Report EmitterDetector Alexander Kloth Edited by Brian Wiggins TABLE OF CONTENTS 1 INTRODUCTION 3 2 THEORY AND PREDICTIONS 4 3 FUNCTIONAL MODULE DESCRIPTION 5 4 WIRING INSTRUCTIONS 6 5 APPARATUS 7 6 TESTING SEQUENCE 7 7 REFERENCES 7 emitterdetectordoc 2 3 12005 Functional Module Report EmitterDetector Alexander Kloth Edited by Brian Wiggins 1 INTRODUCTION Transistors for all intents and purposes are voltage or current switches When the base on the linear transistor receives a signal it allows a current to run from the collector to the emitter This is a step up from mechanical switches Another sort of physical response is in the form of sensing Sensors detect changes in a userindependent physical stimulus humidity and temperature are a few examples These devicesiand necessarily their stimuliiinclude optoelectronic sensors pressure sensors and temperature sensors and humidity sensors Here we deal with an optoelectronic sensor The optoelectronic sensor that we use in the lab is a non amplified emitterdetector The emitterdetector releases an infrared signal across the device s gap This signal is received on the other side of the gap and then induces a current The purpose of this manual is to explain the operation of the emitterdetector In addition we will describe the conditions under which the device s function varies Figure 1 shows the optoelectronic emitterdetector circuit O Cl m r O Figure 1 Optoelectronic emitterdetector circuit emitterdetectordoc 3 3 12005 Functional Module Report EmitterDetector Alexander Kloth Edited by Brian Wiggins 2 THEORY AND PREDICTIONS The emitterdetector works in the same way that a transistor allows a collector emitter current to ow once a base current is induced It allows a current to ow across the detector once the detector picks up the infrared signal from the emitter The emitter for all practical purposes is a diode A signal comes in from the input voltage passes across the emitter and then to the ground The signal cannot ow backwards The voltage drop across the emitter is responsible for the release of infrared light to the detector When the gap between the emitter and the detector is unobstructed current ows across the detector when the gap is obstructed no current ows The detector for all practical purposes functions in the same way as the collectoremitter on the linear transistor Once the detector receives a certain amount of infrared light from the emitter a certain amount of current ows to the ground This current varies with the amount of light received A number of scenarios can explain this variance First if the slots on the emitterdetector are not lined up this does not allow the maximum number of infrared photons to pass across the gap Second if the gaps are too far apart but lined up the number of photons received by the detector slowly decreases when it travels through the gap This is mainly due to the fact that light is scattered according to an inverse square law which states that the number of photons in a square foot vary inversely as the square of the distance from the source Thirdly a decrease in the current across the emitter would result in fewer released photons which would again decrease the current across the detector Regardless of the cause for variation the signal across the detector varies linearly there are no other characteristics of the circuit that would affect the current In an aligned emitterdetectordoc 4 3 12005 Functional Module Report EmitterDetector Alexander Kloth Edited by Brian Wiggins emitterdetector at a fixed distance the amount of current should vary linearly with the current across the emitter Notice that in this circuit there is a second diode a lightemitting diode LED This LED is not a fundamental part of the circuit It is simply to show that the emitter detector is working The LED uses the voltage drop across it to generate a certain amount of light Experimentation shows that this voltage drop is always 18 volts For an allowed voltage down to 18 volts the voltage after the diode is always the pre existing voltage minus l8 volts Below 18 volts 18 volts is always allowed across the diode and the nal voltage is zero This variance of voltages is mainly a function of the ballast resistor after the diode 3 FUNCTIONAL MODULE DESCRIPTION Figure 2 contains a picture of the emitter detector functional module The major electronic components in the following functional module are the resistors the emitter light emitting diode the detector diode the input terminal and the ground terminal The input terminal receives 5V and the ground terminal receive 0V The functional module consists of one circuit in which the circuit is broken when an item is placed in between the emitter and detector emitterdetectordoc 5 3 l 2005 Functional Module Repon EmitterD ete ctor xander Kloth Ale Editedby Brian Wiggins Resistors Figure 2 Picture of Emitter Detector Functional Module 4 WIRING INSTRUCTIONS Table 1 Wiring of the Emitter Detector Detector to ground 0 volts emitterdate ctor doc 6 312005 Functional Module Report EmitterDetector Alexander Kloth Edited by Brian Wiggins 5 APPARATUS Table 1 Apparatus Needed for Testing or source 6 TESTING SEQUENCE Connect the ground alligator clip to a wire and place the wire in the ground terminal of the voltage source Connect the 5 V alligator clip to a wire and place this wire in the 5V terminal Take note that the LED display is lit up This means that the detector is receiVing an infrared signal from the emitter Place a sheet of notebook paper between the emitter and detector and look at the LED Notice that the LED is not lit up This is because the detector is not receiVing any signal from the emitter thus there is no voltage across the LED 7 REFERENCES GIURGIUTIU VICTOR Notes Concerning Mechanical Engineering 367 Fundamentals of Microcontrollers emitterdetectordoc 7 3 12005