Yougothroughthoseotherresistorandyou'redownhereatgroundzeroandwhatthatdoesthatsetsuptheseinputsfortheseComparatorTzeAndthewaytheComparatorisworkisthere's a positiveinputin a negativeinput.
Sowhat's gonnahappeniswe'regonnahave a currentflowingthroughthisone k resistorthroughthe 100 k resistorandintothiscapacitordownhere, thisonemicrophonecapacitorand a capacitorisgoingtostarttocharge.
Andsothenwhathappensisyouknow, currentcannowflowthroughtheone k resistorthroughthisdischargetoground.
Okay, that's that's notveryexciting.
Butwhat's moreinterestingisthatcurrentcanalsoflowfromthecapacitorthroughthe 100 k resistor.
SobeforewewerechargingthecapacitorinthisdirectionNowwe'redischargingthecapacitorcurrentisflowingfromthecapacitorthroughthe 100 k resistorandthroughthisdischargeintothecapacitorisgoingtostarttodischargeanditwilldischargeforfor a while.
Well, I figuredoutthemystery, sowecalculated 100 and 39 milliseconds, andwe'reseeingaboutdoublethat.
Andtheproblemturnedouttobethesecapacitors.
So, youknow, looking, it's capacitor.
Itsaysone m f d 50 v.
So I wouldassumethatthatmeansit's a oneMicrofaredcapacitor 50 volts.
It's gotthis 10 to 2.
I assumethatthat's ahdatecodeofsomesort.
Maybeit's manufacturedin 2010 the 22ndweekofthat, andthat's allitsaysonit.
So I wouldassumeistheoneMicrofaredcapacitor, uh, turnsoutwhen I hookituptomymeter.
HehadmeasureshadtomicroFarage's, so I don't knowwhat's goingonwiththat I got a wholebucketofthesethingsandtheyallsayone M f D onhim, andtheyallreleasedalltheones I measuredmeasuretoMicroFareed's.
I alwaysassumedthesewereonemicrofair, butapparentlyapparentlynot.
Ifanyoneknowswhythey'remarkedthatway, maybemaybe I'm missingsomethingobvious, but I wouldassumethatone m f d meansoneMicrafired, butapparentlyone m f d meanstomicroparentsgofigure.
Yes, the 263 millisecondsthatthat's muchmorewhatwedoexpect.
Andsoifwetakeoneover 263 milliseconds.
Wegetabout 3.8 s O thattellsusthatshouldbeflashingabout 3.8 timespersecond.
Andthatlittlevisuallyseemsaboutright.
So I thinkwe'realmostdonewiththiscircuit.
Itlookslikeit's working.
I didwanttotalkjustbrieflytheresomepowersupplyrecommendationsinthedatasheets.
And I wanttotalk a littlebitaboutpowersupplywe'vegotThisisjust a cellphonecharger.
ThisisfromApple, whichisactuallyverygoodpowersupplyifyouget a genuineAppleone.
Yeah, there's a bunchoftransistorsinhereswitchinganddoingwhatevertheydioandyouknow, whentheyswitch, there's a differentcurrentrequirement, sothey'repullingmorecurrentortheywanttopullmorecurrentfromthepowersupply, andthey'renotabletopullthatcurrent a CZasquicklyastheywouldliketo.
Andyousay, Well, thewireisjustgonnaIt's a conductor, youknow, justelectronsflowrightthrough.
Noproblem.
Well, almost.
Youknow, in a perfectworld, sure, that's howwirewouldwork.
But, uh, we'rewe'renotin a perfectworld.
Andso, uh, thisthiswirehassomeimpedance.
It's actuallyactingasaninductive.
Sowhenyou'vewoncurrentthroughthewire, youget a magneticfieldthatbuildsuparoundit, andthatmagneticfieldisgonnaresistchangestothecurrentthatflowsthroughthatwire.
Andsowhenwetrytopullmorecurrent, weget a littlebitof, ah, ovenimpedance.
That's resistingthat.
Andso I demonstratethisbygettingallofthiswireoutofhereandhookingupthisshort, shortUSBcablethat I'vethat I'vehookedup, and, uh, plugthatin.
Okay, sowe'veaddedarezeropoint 01 microfaredcapacitorheretopinfive, andwe'vealsogot a 0.1 microfaredcapacitywasjustsittingacrossourpowerpinsand I'm gonnamovethatoverherejustsoit's a littlebitmoreoutoftheway.
Butit's stillconnectedtotheboardacrossthepowerpins, whichwhich I thinkisgoodenough.
There's oneotherthingthatthedatasherecommends, whichispinforwhichwedon't haveanythingconnectedto, and I didn't drawitonthediagramhere, butwhatpinforisisitkindofgivesyouthisotherconnectionheretototheresetofthelatch.
Soitgivesyoukindof a directconnectioninheretojustresetthislatchifyouwantedto.
Itgoesevenfaster, andifweturnitalltheway, it's I don't knowifyoucanseethat I canseeit's basicallyflickeringbecauseit's justgoingsofast, becauserightnow, withthisturnedallthewaydown, wejusthave a one K resistor.
Andsowhenit's charging, it's chargingthroughto K ofresistors, andthatisdischargingthroughone K, andsoyoucouldprobablydothemathandfigureouthowfastit's flashing.
But, uh, I likethatyoucangetitkindofdialedintowhateverspeedwewant.
Ifwewanttogoreallyslowagain, we'reusing a clockfor a computersowemaywaymaywanttogoreallyslowtoseeexactlywhat's goingon.
Wecoulddothat.
Butwemightalsowanttojustmanuallycontroltheclockbypushing a button s sowecangoasslowaswewant.
Andsowe'lllookatthatinthenextvideo.
Thereare a lotofwaystobuild a clockcircuitfor a computer.