ࡱ> .0-5@ K bjbj22 "(XX98  }}}       $ R9 }["}}}9 SN  }L } ` : ,  v&4 d 0 Z|Z Z 8}} }}}}}9 9 y Electronics Light Emitting Diodes Name  Light emitting diodes (LEDs) are extremely useful and reliable lights. They are very easy to use and are available in a range of colours and shapes. But in order to use them correctly in a circuit they need a series resistor, to protect them against large currents. Large currents cause them to get hot and burn out. The value of the resistor used depends on the type of Led used, the current it can safely handle and the voltage of the power supply. The value of the resistor is calculated using Ohms Law like this: Examples to calculate: Red LED If 25mA, Vf 2.5V Yellow LED If 30mA, Vf 2.1V Blue LED If 30mA, Vf 4.5V Yellow Ultra bright If 50mA, Vf 1.8V Preferred values Resistors are only available in set ranges such as E12, E24 series etc. The most commonly used is the E12 series, which has the following values only: 10 12 15 18 22 27 33 39 47 56 68 82 The values are these values and the decades above these values eg. 18, 180, 1.8K, 18K, 180K, 1.8M. There is an upper limit: no resistors above 10M are made. When selecting a resistor it is good practice to always select the next highest value. Below are some example values, what preferred values would you use for them? 248K 225 ohms 540K 48K 110 ohms 1.6M 4.6M 320R  FILENAME 2d Prep LEDs and Preferred values page 8 #$)*+ W Z         > ? H I J K ιιιιΧrhdhC|hC|CJOJQJ&jhC|CJOJQJUmH sH *$h3~CJOJQJmHnHsH u*hC|CJOJQJmH sH #jhC|CJOJQJUmH sH hOJQJh\h\5OJQJh\OJQJjhveoCJUmHnHuhveohveo5CJaJhveohveo5 h\>**,3 4 K L e g q ####Y##Y##Y###########Y + d 9!  & Fd  p# gdveo J    H I J K #Y#Y#Y#Y + d&1h:pveo/ =!"-#$%n ~L[:+E$PNG  IHDR4GsRGBPLTE """)))UUUMMMBBB999|PP֭3f333f3333f3ffffff3f̙3ff333f333333333f33333333f33f3ff3f3f3f3333f33̙33333f333333f3333f3ffffff3f33ff3f3f3f3fff3ffffffffff3ffff̙fff3fffff3fff333f3f3ff3ff33f̙̙3̙ff̙̙̙3f̙3f̙333f3̙333f3ffffff3f̙̙3f̙3f3f333f3333f3fff̙fff3f̙3f3f̙fffffffff!___www˲𠠤X"N pHYsjjzIDATx^]6|ٵ7”T%񌈫ʿ|?}] P;?l W +_ ^uh?sU@8f4 |PC&xU/bBf2 1Q?ڽ0:=n 5=ѴF/n4}`nLÍyxSN 7⍦O8=;эOTV6`<ޤͭ-hr98Դ[[ɮ.1ݭ-X`dέ-X-WQ/O܂5VUîV,1t2V<d0|2agmˊnAití-x`ĆR!?@0+~hw{eKnZ]b3]h?ge 4,p-TgX K-T~JVm+م`DxD0<<,tϙM (^ĀU@+Hw*Պ%BfX% [64  B l8FX lze"py1 K3a0<@9LZ] SU6)"ל{P_4k{3U!9@y ȋE-cvԻh5p7S ɖQ}4A4D@y7ѨLCҥZTq7Rh6`aWV_߉"V5 v:={Q_6{نc\FLV{WiL(pNB"C<"䚹|p9yXcp"_X>{8v ׿3p% p 7C^=9: J`hk(1QY e%)¼+K(1 ®.aN!]]ByHvEv st 0/xC0pk/g¶iA8E` 6w~KLj3U$hf2<* Mn:f:EEvo̦)g~?8@#Lӫ`NCO]U0Lvε|zT;h:ݣ'8KaKMr3<%*##]"UVgaxpI: n :%ṕJ6cñ-!;#O9<9;;|; ؁m<9;;|; ؁m<9;;|; ؁m<9;;|; ؁mlF{W0F~oAq~-xT93T&< "~4" T>Q5t Snc~o\(||` dT=mf:)Х TE[$5&Ik 'm^Ao@o6e$u> R]L*/Y5'Z@ܞ VK`bnnam']<]קvN VKgfÀ g{.ѥcg{L53u]e@/Ÿ혒OQU$)Y4=FF@&#&n. ݡ1EiC (G\b3M̢A/a QΚO=Z,0X:1]8!(h*W9FkcN(Q6[AM[*d*Vz "Qu}YAbB]TPw:9cIzd-޾d YdS@u&,Bx@( TpX-~qCWy&'RHn:=sUdŝѐp  y>lT쵛YHZ,q,{-LK+Ah)lޞfe.p <,!Yej/F^u/ fQroxq!Um3TȚPuNm/c(T|:eID?-sp5pi~GOdS ׽pcX5Bg)rm]pJg lz'I#{b1"-3Gۂ: [x"& @dtA>AGo.,Sn,AUXbڒ恗`E0zn_wX ^e!|Ul@`;>G^\I08T( 57Hg@@o>F),D+A ( PSc$*nQVݓ B4e#]1='" @!B/@g47=#r$bPL[Pu$% SȟS#@P4X\l EEpZM@"=쁣5=@so>M%<"C0F=@q @uSlLv@Ye;=`|lF<"Y=[h18b&gݺ?RIENDB`@@@ NormalCJ_HaJmH sH tH Z@Z Heading 1$<@&5CJ KH OJQJ\^JaJ J@J Heading 2$@&5>*OJQJ\^JDAD Default Paragraph FontViV  Table Normal :V 44 la (k(No List 4@4 Header  !4 @4 Footer  !H@H A#& Balloon TextCJOJQJ^JaJK zK*,34KLegqHIL000000 00 00 00 000000000000000<;000 888;K  K  J K -;l,b$ ~L[:+E$(@t(  <  # A B S  ?*Kb&fT]_{}?IL?IL::#)*+?AGILL DCSDCSDCS C J LeighChristopher LeighNИ,2kИ,@hh^h`.@hh^h`.2kNA#&veo}8|C|3~9+\L@ K`@UnknownGz Times New Roman5Symbol3& z Arial5& zaTahoma"1hwfzz P P $4d+7QH?\#Electronics  Light Emitting DiodesDCS C J Leigh  Oh+'0  , H T ` lx$Electronics Light Emitting DiodeslecDCSCSCSNormaln C J Leighs 9J Microsoft Word 10.0@0@c`@>*Q@>4P՜.+,0 hp  Dean Close School  A $Electronics Light Emitting Diodes Title  !"#$&'()*+,/Root Entry F (11TableWordDocument"(SummaryInformation(DocumentSummaryInformation8%CompObjj  FMicrosoft Word Document MSWordDocWord.Document.89q