makingthings electronics

BASICELECTRONICSMediaTheory&Practice

BASICELECTRONICSDavidWilliams&MichaelShiloh

2003MakingThingsLLC


OVERVIEWSession1

Electricityiskindoflikewater

TheComponentsInside

TheBinaryMiracleSession2

Switchescandoallthat?

Arrangethemjustright,andyouhaveacomputer

Thecomputerdoeswhatyousaymillionsoftimesasecond

Reconnectingtotherealworld


ELECTRICITYISLIKEWATER


LEVELSOFUNDERSTANDINGHowmuchdoyouneedtoknow?

Toownacaryoudonotneedtounderstandthedetailsofinternalcombustionengines,butthedetailsleakout:gasoline,oil,batteries

Todoelectronicsyoudon'tneedadegreeinmaterialsscienceorsolidstatephysics,butthedetailssometimesleakout:voltage,current,OhmsLaw,etc.

Thissessionandthenextarewhatwethinkyou'llneedtoknowtobegintohaveanintuitivegraspoverthefieldofelectronics.


ELECTRICITYThinkofelectricityflowinglikewaterinapipeTheanalogytowaterisnotperfect,butithelps.Electronsarepresentandquitemoveableineveryconductor.

Electricityistheorderedflowofelectronsinaconductor.


VOLTAGEANDCURRENTVoltageislikewaterpressure

MeasuredinVolts,VCurrentislikewatervolume

MeasuredinAmps,A1/1000thofanAmpisamilliampmA

PowerisVoltagexCurrentMeasuredinWatts,W1/1000thofaWattisamilliwattmW


RESISTANCEAlmosteverythingthatconductselectricityhasaresistance.Itdoesntconductitperfectly.

ResistanceismeasuredinOhms()1000=1k1,000,000=1M


OHMSLAWRelatesVoltageandCurrentinasimplecircuit

V=IRVolts=Current(I)xResistance(R)

(thismeansI=V/RandR=V/I)


CIRCUITSWATERANDELECTRICITY

Electricity,likewater,flowsonlywhenit

can.

Acircuitneedsacompletepath,andasourceof

energy


CIRCUITDIAGRAMSICircuitDiagrams(alsocalledSchematics)areacompacteasywaytorepresentcircuits.

Onlytheessentialdetailsarerepresented.

LiketheLondonUndergrounddrawnforhumanuse


CIRCUITDIAGRAMSIIMorerealisticdiagram

Vcc&GndConnectionsManypathsChip(LM555)Resistors,CapacitorsNonliterallineconnectionsOptionalparts


PRINTEDCIRCUITBOARDSWhenwiringupcircuitswithwiresistoomuchwork

Eachtrace(thinstripofcopper)replacesonewire


DEMONSTRATIONCIRCUITSObjectives

ShowasimplecircuitMeasurevoltages&current

MaterialsBatteryandLampMultimeter


COMPONENTS

Thecomponentsthatmakeupacircuit


CONDUCTORSConnectionsareveryimportant

Manythingsareconductivecarchassis/saltywater

Strandedvs.SolidCoreSolidcoreismuchmorelikelytobreakwhenflexed

AWG(AmericanWireGauge)StandardAWG16LargerPowerConnectionsAWG18PowerConnectionsAWG22GoodInterconnectionSizeAWG30Veryfinebreakseasily


CELLS&BATTERIESChemicalReactionscreatingelectricityLeadacid(carbatteryapprox2V)Alkaline(regularcellsapprox1.5V)LithiumIon(latestrechargeableapprox3.6V)FuelCells(newtechnology)SolarCells(lightconvertedintoelectricity)Fruit!(lemonswithcopperandzincelectrodes)Canputtheminseries(endtoend)toincreasevoltageCanputtheminparallel(sidebyside)toincrease

current


POWERSUPPLIESConnectto110VACtoprovideelectricityinadifferentform.

Beverycarefulwith110V!Itcankillyou.Anythingover50Visdangerous.


SWITCHESANDPUSHBUTTONSConnectanddisconnectcircuits


RESISTORSAsthenamesuggeststendtopresentapartialbarriertoelectricityflow

Recall,ResistanceismeasuredinOhms()1000=1k1,000,000=1MAlsoneedtonoteratedpower(e.g.1/8W,5W)


POTENTIOMETERSVariableResistors

Havearesistancethatvariesaccordingtothemechanicalpositionofoneofitswiper.


LIGHTEMITTINGDIODES(LEDs)Tinylightsourcescomeinavarietyofcolors

Requireverysmallcurrentbutwilltakeallyouofferalwaysusearesistor!Valuesbetween300and1Kareuseful.


DEMONSTRATIONLEDsObjectives

ShowhowtouseanLEDShowhowitonlyworksonewayroundShowhowyouneedaresistorShowhowdifferentresistorsgivedifferentbrightnesses,potentiometers

MaterialsSolderingiron/solder/wireLEDResistor/Potentiometer


CAPACITORSAsthenamesuggeststendtostoreelectricitylikeaminibattery

MeasuredinFarads(F)0.000001F=1F0.000000001=1pF

Alsoneedtonoteratedvoltage

Charging

Charged

Discharging


DEMONSTRATIONCAPACITORSObjectives

Toshowcharginganddischargingcapacitors

ShowchargewithLED/resistorShowdischargewithLED/resistor

MaterialsCapacitor(largevalue)2xResistor/LEDcomboSolderingIron,Solder


DIODESFamilyofcomponentswhichonlyletelectricityflowoneway

Manydifferentkindseachwithdifferentcharacteristics

Maincharacteristictonoteispower(W)


DEMONSTRATIONDIODESObjectives

ToshowdiodesblockingcurrentMaterials

PowersupplyDiode12VLampSolder/SolderingIron


SOLENOIDSElectromagnets

Currentispassedthroughthecoilandamagneticfieldiscreated

Usedtoreleaselatches,lockpartsinplace,etc.


MOTORSFamilyofcomponentsthatusesequencedelectricityandmagnetismtomakemovement

Voltage,Current,Torque&RPMoftenspecified


RELAYSElectromechanicalSwitchesApplyacurrenttothecoilandtheconnectedswitchesareconnectedanddisconnected.

Carsuserelaystoswitch12V,500A!

SiliconRelaysalsoavailablewithnomovingparts


DEMONSTRATIONSOLENOIDS/MOTORS/RELAYS

ObjectivesToshowsolenoids,motorsandrelaysrunning

MaterialsSolenoid/Motor/RelayPowerSupply


VOLTAGEDIVIDERSISimpleandvitalpartofelectronics.Usedthroughout

electronics.Vitalintheconnectionofsensorstocomputers.

Takearesistorandconnectittoapowersource.

Thevoltageononesideis5V,andontheotheris0V

Whatwoulditbeinthemiddleoftheresistor?


VOLTAGEDIVIDERSIICansetthisup:

Taketworesistorsofequalvalueinseriesandconnectthemtoapowersource.

Wecanguessthatthevoltageatpis2.5Vifra=rb.Eachresistordoeshalfthework.


VOLTAGEDIVIDERSIIIAndtoextendthisfurther:

Whatiftheresistorsarenotthesame?

Wecanguessthatthevoltageatpwillbegreaterthan2.5Vifralessvoltagedrop


VOLTAGEDIVIDERSIVNowwehavesomethinguseful

Whatifwesubstituteoneoftheresistorsforaresistivesensorofsomekind?

Wecanguessthatthevoltageatpwillbedependentonthequalitysensed.


VOLTAGEDIVIDERSVVariableResistorscanworklikethistoo

Withthiscircuit,wecansensetherotationalpositionofashaftoralinearposition

Thevoltageatpwillbedependentonthepositionofthewiper.


DEMONSTRATIONVOLTAGEDIVIDERS

ObjectivesTomirrortheforegoingvoltagedividerdiscussionwithvoltagedividerexamples

MaterialsMultimeterSolderingIronandSolderResistorsResistiveSensors(Bend/Light)


TRANSISTORSIDevelopedtoswitchandamplify

Comeinalargenumberofdifferentvarieties,shapesandsizes


TRANSISTORSIIMOSFETsaretransistorsthatmakeverygoodswitches

Averysmallsignalonthegatecanswitchverylargeloadsonandoffthousandsoftimesasecond.


DEMONSTRATIONTRANSISTORSObjectives

ToshowtheoperationofatransistorMaterials

MultimeterSolderingIronandSolderMotor/HalogenBigMOSFETMOSFETdatasheet


BINARY

Thegatewaytodigitalelectronics


THEDECIMALNUMBERSYSTEMAttheriskofstatingtheobvious

Wecountbygoingthroughourlistofnumbersymbolsuntilwerunout

0,1,2,3,4,5,6,7,8,9,

Whenwerunout,wemarkthatfactwithadigitinanothercolumnandstartagain

8,9,10,11,12,13,14,15,

Whenwerunoutagain,weuseanothercolumn

98,99,100,101,102,103,


THEBINARYNUMBERSYSTEMBinaryisidentical,exceptweonlyhave0and1

Wecountbygoingthroughourlistofnumbersymbolsuntilwerunout

0,1,

Whenwerunout,wemarkthatfactwithadigitinanothercolumnandstartagain

0,1,10,

Whenwerunoutagain,weuseanothercolumn

10,11,100,101,110,111,


JUSTLIKEAREALNUMBERINGSYSTEM

Youcanconverttodecimal,sinceyouknowhowbigeachcolumnis32,16,8,4,2,1

11002=1x8+1x4+0x2+0x1=1210

Youcanaddandsubtractbinarynumbers(andallotherarithmeticaloperations)

0010 1000+ 011001101000 0010

Eachcolumniscalledabit.Eightbitsarecalledabyte.


THEBIGSTEPSowhatssocoolaboutanumberingsystemthatonlyhas2digits?

Eachdigitcanbeunambiguouslyrepresentedbyavoltageonawire.

Andyoucandowhateveryouwantwithit.


83Whatis8310or010100112?


MATERIALS


MaterialsPowerSupply1.5VCellWireSolderSolderingIronLEDsResistors(1K&500)PotentiometerDiodes(highishcurrent)BendSensor

PhotocellBendsensorMOSFET&DatasheetMotorsHalogens

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