Teach-In 2011
7($&+ ,1 $ %52$' %$6(' ,1752'8&7,21 72 (/(&7521,&6 0ARTª ª)NTRODUCTIONªTOªSIGNALSªINª ELECTRONICªCIRCUITSªANDªSYSTEMS By Mike and Richard Tooley
/URª4EACH )NªSERIESªISªDESIGNEDªTOªPROVIDEªYOUªWITHªAªBROAD BASEDªINTRODUCTIONªTOªELECTRONICS ª7EªHAVEªª ATTEMPTEDªTOªPROVIDEªCOVERAGEªOFªTHREEªOFªTHEªMOSTªIMPORTANTªELECTRONICSªUNITSªTHATªAREªCURRENTLYªSTUDIEDªINª MANYªSCHOOLSªANDªCOLLEGESªINªTHEª5+ ª4HESEªINCLUDEª%DEXCELª"4%#ª,EVELª ªAWARDS ªASªWELLªASªELECTRONICSªUNITSª OFªTHEªNEWª$IPLOMAªINª%NGINEERINGª ALSOªATª,EVELª ª4HEªSERIESªWILLªALSOªPROVIDEªTHEªMOREªEXPERIENCEDªREADERª WITHªANªOPPORTUNITYªTOª@BRUSHªUP ªONªSPECIlCªTOPICSªWITHªWHICHªHEªORªSHEªMAYªBEªLESSªFAMILIAR ª %ACHªPARTªOFªOURª4EACH )NªSERIESªISªORGANISEDªUNDERªlVEªMAINªHEADINGS ª,EARN ª#HECK ª"UILD ª)NVESTIGATEªANDª !MAZE ª,EARNªWILLªTEACHªYOUªTHEªTHEORY ª#HECKªWILLªHELPªYOUªTOªCHECKªYOURªUNDERSTANDING ªANDª"UILDªWILLªGIVEª YOUªANªOPPORTUNITYªTOªBUILDªANDªTESTªSIMPLEªELECTRONICªCIRCUITS ª)NVESTIGATEªWILLªPROVIDEªYOUªWITHªAªCHALLENGEª WHICHªWILLªALLOWªYOUªTOªFURTHERªEXTENDªYOURªLEARNING ªANDªlNALLY ª!MAZEªWILLªSHOWªYOUªTHEª@WOWªFACTOR ª
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% "%'). THIS NEW 5FBDI *O SERIES BY INTRODUCING THE SIGNALS USED TO CONVEY INFORMATION IN ELECTRONIC CIRCUITS AND THE UNITS THAT WE USE TO MEASURE THE QUANTITIES IN ELECTRONIC CIRCUITS 7E CONCLUDE THIS PART BY LOOKING AT SOME SIMPLE ELECTRONIC CIRCUITS THAT YOU CAN BUILD AND TEST USING #IRCUIT 7IZARD SOFTWARE SEE PAGES AND
3IGNALSªINªELECTRONICªCIRCUITSª ANDªSYSTEMS
4HIS ÚRST PART OF OUR 4EACH )N SERIES WILL PROVIDE YOU WITH AN INTRODUC TION TO THE SIGNALS THAT CONVEY JO GPSNBUJPO IN ELECTRONIC CIRCUITS 7E WILL ALSO INTRODUCE YOU TO SOME OF THE UNITS THAT ARE USED WHEN MEASURING ELECTRICAL QUANTITIES SUCH AS CUR RENT VOLTAGE AND FREQUENCY 9OU WILL LEARN ABOUT THE DIFFERENCE BETWEEN ANALOGUE AND DIGITAL SIGNALS AND HOW
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TO RECOGNISE SIGNALS FROM THE SHAPE OF THEIR WAVEFORMS "EING ABLE TO lREADm AND INTERPRET A CIRCUIT DIAGRAM OR lSCHEMATICm IS AN ESSENTIAL SKILL REQUIRED OF EVERY ELEC TRONIC TECHNICIAN AND ENGINEER -ANY DIFFERENT PARTS AND DEVICES ARE USED IN ELECTRONIC CIRCUITS AND IT IS IMPORTANT THAT YOU SHOULD BE ABLE TO RECOGNISE THEM BOTH FROM THE SYMBOLS THAT WE USE TO REPRESENT THEM IN THEORETICAL CIRCUIT DIAGRAMS AND ALSO FROM THEIR PHYSICAL APPEARANCE
,EARN 3IGNALSªANDªSIGNALªCONVERSION
)N ALL FORMS OF COMMUNICATION SIG NALS ARE USED TO CONVEY INFORMATION 4HE SIGNALS THAT WE USE IN EVERYDAY LIFE CAN TAKE MANY FORMS INCLUDING ÛASHING LIGHTS SHOUTING WAVING OUR HANDS SHAKING OUR HEADS AND OTH
ERS FORMS OF lBODY LANGUAGEm )N FACT LIFE WOULD BE VERY DIFÚCULT WITHOUT SIGNALS q THINK ABOUT DRIVING A CAR OR MOTORBIKE IN HEAVY TRAFÚCØ )N THIS SECTION WE WILL LOOK AT HOW SIGNALS ARE USED IN ELECTRONICS HOW THEY CAN BE CONVERTED FROM ONE FORM TO ANOTHER AND HOW THEY ARE MEASURED )N ELECTRONICS SIGNALS CAN TAKE MANY FORMS INCLUDING CHANGES IN VOLTAGE LEVELS PULSES OF CURRENT AND SEQUENCES OF BINARY CODED DIGITS OR CJUT 3IGNALS THAT VARY CONTINUOUSLY IN LEVEL ARE REFERRED TO AS ANALOGUE SIG NALS WHILE THOSE THAT USE DISCRETE IE ÚXED LEVELS ARE REFERRED TO AS DIGITAL SIGNALS 3OME TYPICAL ANALOGUE AND DIGITAL SIGNALS ARE SHOWN IN &IG .OTICE HOW THE DIGITAL SIGNAL EXISTS ONLY AS A SERIES OF DISCRETE VOLTAGE LEVELS WHILE THE ANALOGUE SIGNAL VARIES CONTINUOUSLY FROM ONE VOLTAGE LEVEL TO ANOTHER
Everyday Practical Electronics, November 2010