Isit a goodideatobuildanentirecomputerfromscratchonbreadboardslikethis?

Well, mightseemlike a strangequestionforsomeonewho's basicallymadeanentireYouTubechanneloutofdoingpreciselythat.

And I sellkitswithallthepartssoyoucandoityourself.

Soobviously, I'm a prettybigfanofbuildingcomputersonbreadboards, andthebigreason I reallylikeitisthatitforcesyoutothinkthroughhoweverythingworks.

Youknow, theyfeltlikesomethingwasmissingwiththeseprojects, whereyouget a premadecircuitboardandyoujustsawher a bunchofcomponentstoit.

Anddon't getmewrong.

It's greatifyouwanttolearnhowtoSauder, Butonceyouknowthat, I justdon't seehowattaching a bunchofcomponentsto a circuitboardteachesyoumuchaboutelectronics.

Andasyoubuildeachsectiontesting, youknoweachasyougo, there's a verygoodchancethingsaren't goingtoworkperfectlythefirsttime.

Andthat's a goodthing.

Youknow.

Itforcesyoutothinkaboutwhy, andithelpsyoubuild a deeperintuitionforhowitallworks.

Andsothat's what I reallylikeaboutdoingbigprojectslikethisonbreadboards.

Butasidefrombeing a lotmorework, whichwhich I thinkis a goodthing, therearedefinitelysomecaveatstobeawareofwhenbuildingcomplexprojectslikethisonbreadboards.

First, notallbreadboardsarethesame.

There's a bigdifferenceinqualitybetweenthecheap $2 breadboardsyoucangetand a higherquality, youknow, eightor $9 breadboard.

Andit's truetheylookprettysimilar.

Butlet's take a lookinside.

Eachrowonthebreadboardisconnectedwith a metalstripthatgrabsthewiresthatareinserted, andif I digunderthebackinghere, um, I canremovethatmetalpiecesowecouldtake a closerlookatit.

Andhereitis, whatitlookslike, havewetake a closerlook?

Youcanseethewiresairinsertedlikethishereandmakecontactwithmetalhereandin a goodqualitybreadboard.

SothequalitytheBridgeportmatters, youcanruninto a lotofproblemsbuilding a morecomplexprojectlike a computeronthesecheaperbreadboards, becauseyoujustcan't beassuredthatallthewiresaremakinggoodcontact.

Andyoucancheckoutmywebsiteformoreinformationonwhatbreadboards I recommend.

Butokay, evenwiththebestbreadboards, there's still a lotoflimitationstobuilding a complexdesign, like a computeronbreadboards, versus a customprintedcircuitboard.

Oreventhese, youknow, Stoddardprototypingboards.

Andthat's becausethephysicalpropertiesoftheconductorsin a circuit, whetherthat's thetracesontheprintedcircuitboardorthewiresandbreadboardsinsomethinglikethis, youknow, thoseconductorsandeverythinghavephysicalpropertiesthataffectthecircuit.

Soif a if a chipisswitchingcircuitonandoff, andithastodrawmorecurrenttodothat, wedon't wantthevoltageonthatpowerrailtodrop.

Andsoit's actually a goodpracticetoaddsomecapacitorsjustacrossthepowerraillikethis.

Soactually, at a coupleof 0.1 microfaredcapacitorshereacrossthepowerrailstohelpstabilizethefivevoltsthatareonthispowerrailsandreallythebestpracticehereistohaveoneofthesecapacitorsforeverychipthat's oninyourcircuit.

So, forexample, wecouldhave a capacitorheredirectlyfromfivevoltstogroundacrossthispowerrailfourforthischipherelikethis.

Andthatmeansthatifthischiphashasanychangeintheamountofcurrentitneedstodrawfromthefromitspowerrails, it's alwaysgoingtosee a consistentfivevoltsorasclose a czcloseaswecangettothat.

Andthat's I guessoneoftheothermaybedrawbacksofbreadboardsisthatit's, youknow, kindofhardoratleastinconvenient.

Togetthesecapacitorsdirectlyacrossthepowerrailsof a chiplikethis, you'vegottokindofputitacross, andsomeofthesechips, they'rethepowerswerejustkindofinaninconvenientplace.

But I thinkyouknow, forwhatwe'redoing, it's probablygoodenoughjusttohave a couplecapacitorsherethesewillstillhelpstabilizethepowerrailswithoutreallygettinginthewaytoomuch.

Inthatcapacitor, you'remorelikelytohave a lotmorecapacitancein a breadboardcircuitjustbecauseyou'vegot a lotmoremetalinhere, youknow, inthebreadboardandinallthesewires, thenyoumighthaveinothertypesofcircuits.

Now, anotherrelatedphenomenonisinductinCE, andifyou'velearned a littlebitofphysics, youmightknowthatanytimeyouhave a currentflowingthrough a wirelikethis.

There's a magneticfieldthathasgeneratedaroundthatwire.

Course, ifyouhave a lotofwire, uh, especiallywounduplikethis, youcanusethatmagneticfieldtodowork.

Andthat's howthemotorworks.

Andthatactuallyworksinreverseaswell.

Rightnow, I'm usingcurrenttogenerate a magneticfieldthat's pushingagainstthisfixmagnethere.

Butanymotorisalso a generator, andthat's because a changingmagneticfieldaroundthewirewillinduce a voltageinthewire.

Sowhen I spinthis, themagneticfieldfromthepermanentmagnetchangesrelativetothewireandinduces a voltageinthewire.

Sowhatdoesthismeanfor a breadboardcomputer?

Well, youknow, ifyou'vegot a wirewiththecurrentgoingthroughit, you'regonnahave a magneticfieldaroundthatwire.

SoSoifwegofrom a smallercurrentto a largercurrent, we'regonnagofrom a smallermanmagneticfieldto a largermagneticfield.

Remember, ifyouhave a changingmagneticfieldaroundthewirethanthevoltagethat'llinduce a voltageinthewire.

Anditjustsohappensthatthevoltagethat's inducedwillopposethechangeincurrentandsay, you'vegotcapacitance, whichopposes a changeinvoltageandinductinCE, whichopposes a changeincurrent.

That's potentiallyalternatingbetweenzeroandfivevolts a 1,000,000 timespersecond.

Youknow, thatcouldbe a problem.

Well, wecanrun a littleexperiment.

I'vegot a breadboardherewith a bunchofconnections, and I canfeed a signalinononeside, andyoucansee I'm measuringthatsignalaswell.

Ifwelookinthetelescope, youcanseethere's this 100 kilohertzsinewavethatwe'remeasuringgoingin, andsothatgoesinonthisside, andthenitgoesthrough a wholebunchofconnectionsandwecanmeasureitcomingoutoverhere.

I alsohave a resistorheretokindofisolatetheinputandoutputmeasurements.

Andasidefromthatinducedcurrentthatwe'regonnabelookingatthat I mentioned, I don't expectanycurrentflowingthroughthatresistor.

We'restartingtoseeThebluelineisalsodippingby a fewdecibels.

Isthatshowingthatithigherandhigherfrequencies?

We'restartingtolosesomeofoursignalintegrity.

Somethingelseiskindofinterestingifwegobackandjustlookatthewayformshere, rememberthattheattenuationinphaseshiftthatwe'reseeingis a resultofbothcapacitancebetweenconductorshereaswellasinductinCE, whichisactually a magneticfieldthat's generatedaroundtheseconductors.

Soifweactuallychangesortofthephysicalshape, herearepropertiesor, youknow, sortofrelationshipsbetweenthedifferentwires, youcanseejustas I pokeitthisthatthephaseshiftandtheattenuationthatwe'reseeingischanging a bitaswell.

Andyouknow, thisis a 20 megahertz, but I I thinkthat's prettyinterestingtoseethatsheconcededhigherfrequencies.

So, youknow, inreality, becausehighfrequencieslike 150 megahertzaregonnabeverysusceptibletosmallamountsofcapacitanceandsmallamountsofinductinCElikewe'vegotinin a breadboardcircuit.