ForourotherthreefreeeBooks,Goto:1-100TransistorCircuitsGoto:101-200TransistorCircuitsGoto:50-555CircuitsSeeTALKINGELECTRONICSWEBSITEemailColinMitchell:talking@tpg.com.auINTRODUCTIONThisisthethirdpartofourCircuitse-bookseries.Itcontainsafurther100circuits.ThistimewehaveconcentratedoncircuitscontainingoneormoreIC's.It'samazingwhatyoucandowithtransistorsbutwhenIntegratedCircuitscamealong,thewholefieldofelectronicsexploded.IC'scanhandlebothanalogueaswellasdigitalsignalsbutbeforetheirarrival,nearlyallcircuitswereanalogueorverysimple"digital"switchingcircuits.Let'sexplainwhatwemean.Thewordanalogueisawaveformorsignalthatischanging(increasinganddecreasing)ataconstantornonconstantrate.Examplesarevoice,music,tones,soundsandfrequencies.Equipmentsuchasradios,TV'sandamplifiersprocessanaloguesignals.Thendigitalcamealong.Digitalissimilartoaswitchturningsomethingonandoff.Theadvantageofdigitalistwo-fold.Firstlyitisaveryreliableandaccuratewaytosendasignal.ThesignaliseitherHIGHorLOW(ONorOFF).Itcannotbehalf-onoronequarter-off.Andsecondly,acircuitthatisON,consumestheleastamountofenergyinthecontrollingdevice.Inotherwords,atransistorthatisfullyturnedONanddrivingamotor,dissipatestheleastamountofheat.IfitisslightlyturnedONornearlyfullyturnedON,itgetsveryhot.Andobviouslyatransistorthatisnotturnedonatallwillconsumenoenergy.AtransistorthatturnsONfullyandOFFfullyiscalledaSWITCH.Whentwotransistorsarecross-coupledintheformofaflipflop,anypulsesenteringthecircuitcauseittoflipandflopandtheoutputgoesHIGHoneverysecondpulse.Thismeansthecircuithalvestheinputpulsesandisthebasisofcountingordividing.Itisalsothebasisofa"MemoryCell"aswillwillholdapieceofinformation.DigitalcircuitsalsointroducetheconceptoftwoinputscreatingaHIGHoutputwhenbothareHIGHandvariationsofthis.Thisiscalled"logic"andintroducestermssuchas"Booleanalgebra"(Booleanlogic)and"gates."IntegratedCircuitsstartedwithafewtransistorsineach"chip"andincreasedtominiormicrocomputersinasinglechip.ThesechipsarecalledMicrocontrollersandasinglechipwithaf...
