INFO: Resistance for LED's / Determinating Resistor Values

6th June 2002, 23:42

Glory,

Heb al veel mensen gehoord die niet weten welke weerstand bij welke led hoort.

de formule is echter simpel :

Code:

R=(U-Ud)/I

dus: Weerstand = ( inputvoltage - doorlaatvoltage van de led) / stroomsterkte

inputvoltage; waarschijnlijk 12v of 5v
doorlaatvoltage van de led; hangt af van het soort ledje. Rode leds hebben laten minder door, blauwe laten meer door... neem 2,5 als universeel getal als je het niet weet.
Stroomsterkte; meeste leds verdragen 0,02 Ampère max.
sommige high bright leds tot 0,05 Ampère..
ook hier kun je 0,02 ampère als universeel getal nemen.

U kan dan berekenen bijvoorbeeld:

Een standard ledje op 12 volt aansluiten :

Code:

U = 12 v
Ud=2,5 v
I=0,02 A
R = (12-2,5)/0,02 
R = 475 Ohm

De dichtstbij gelegen waarde is 470 Ohm

hope this clears things up :wtf:

Greetz Anthro

jmke · 6th June 2002, 23:48

any chance in a translated version for our non-dutch speaking folk?

great post

quality over quantity!

6th June 2002, 23:59

oke morgen komt er een vertalingske, nu slapen... Morgen exaam Frans

uke:

TerAngreal · 7th June 2002, 00:05

seen there are still so many people not knowing which resistance should be used for which LED ...

the formula is rather simple actually:

Code:

R=(U-Ud)/I

meaning:

Code:

Resistance = (Mains Voltage - LED Voltage) / LED ampère

Mains Voltage = most likely +5V or +12V
LED Voltage = depends on the led itself. Red LED's pass on less, blue LED's pass on more voltage ... if you're not quite sure, take 2,5 as a universal value
LED Ampère = most LED's can only take 0,02A max !
(exception: some high bright LED's can take up to 0,05A)
here 0,02A might be used as universal value

so - example given:

Code:

U = +12V
Ud = +2,5V
I = 0,02A

==> R = (12-2,5)/0,02 = 475 Ohm

the closest value is 470 Ohm in this case ...

Hope this clears things up :wtf:

---------------------------------------------------------------------------------------

all credits go to Anthroplast

(fair enough ? had nothing to do for about 3 minutes ...)

7th June 2002, 11:33

nice work

8th June 2002, 16:11

can you give wich values resistors have?
between 50 and 1000 ohm or something...

DUR0N · 8th June 2002, 17:47

Quote:

Originally posted by TeuS
can you give wich values resistors have?
between 50 and 1000 ohm or something...

hèhè, those colored strips on the resistor indicate it's resistance...

google tells me this: http://webhome.idirect.com/~jadams/e...stor_codes.htm

and: handy calculator: http://webhome.idirect.com/~jadams/e...esist_calc.htm

[Bonbon] · 9th June 2002, 23:31

MEEEP error

Ter·Angreal posted in the translation:

Code:

R=(U/Ud)-I

and this should be

Code:

R=(U-Ud)/I

as in Anthroplast's dutch post
at least someone is awake @ 23h40

TerAngreal · 10th June 2002, 13:02

point taken & formula corrected

tnx [Bonbon]

you try and translate that text after spending a couple of hours learning physics and chemistry ... eat me

10th June 2002, 16:58

I know, duron

my blue leds need 435 ohm resistors
nearest value: 470

=>NEED THOSE VALUES!

6th June 2002, 23:42	#1
Anthroplast Posts: n/a	Weerstand voor leds Glory, Heb al veel mensen gehoord die niet weten welke weerstand bij welke led hoort. de formule is echter simpel : Code: R=(U-Ud)/I dus: Weerstand = ( inputvoltage - doorlaatvoltage van de led) / stroomsterkte inputvoltage; waarschijnlijk 12v of 5v doorlaatvoltage van de led; hangt af van het soort ledje. Rode leds hebben laten minder door, blauwe laten meer door... neem 2,5 als universeel getal als je het niet weet. Stroomsterkte; meeste leds verdragen 0,02 Ampère max. sommige high bright leds tot 0,05 Ampère.. ook hier kun je 0,02 ampère als universeel getal nemen. U kan dan berekenen bijvoorbeeld: Een standard ledje op 12 volt aansluiten : Code: U = 12 v Ud=2,5 v I=0,02 A R = (12-2,5)/0,02 R = 475 Ohm De dichtstbij gelegen waarde is 470 Ohm hope this clears things up :wtf: Greetz Anthro

6th June 2002, 23:48	#2
jmke Madshrimp Join Date: May 2002 Location: 7090/Belgium Posts: 79,022	any chance in a translated version for our non-dutch speaking folk? great post quality over quantity! __________________

7th June 2002, 00:05	#4
TerAngreal Member Join Date: May 2002 Posts: 1,343	seen there are still so many people not knowing which resistance should be used for which LED ... the formula is rather simple actually: Code: R=(U-Ud)/I meaning: Code: Resistance = (Mains Voltage - LED Voltage) / LED ampère Mains Voltage = most likely +5V or +12V LED Voltage = depends on the led itself. Red LED's pass on less, blue LED's pass on more voltage ... if you're not quite sure, take 2,5 as a universal value LED Ampère = most LED's can only take 0,02A max ! (exception: some high bright LED's can take up to 0,05A) here 0,02A might be used as universal value so - example given: Code: U = +12V Ud = +2,5V I = 0,02A ==> R = (12-2,5)/0,02 = 475 Ohm the closest value is 470 Ohm in this case ... Hope this clears things up :wtf: --------------------------------------------------------------------------------------- all credits go to Anthroplast (fair enough ? had nothing to do for about 3 minutes ...)

9th June 2002, 23:31	#8
[Bonbon] Member Join Date: Jun 2002 Posts: 692	MEEEP error Ter·Angreal posted in the translation: Code: R=(U/Ud)-I and this should be Code: R=(U-Ud)/I as in Anthroplast's dutch post at least someone is awake @ 23h40

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6th June 2002, 23:59	#3
Anthroplast Posts: n/a	oke morgen komt er een vertalingske, nu slapen... Morgen exaam Frans uke:

8th June 2002, 16:11	#6
TeuS Posts: n/a	can you give wich values resistors have? between 50 and 1000 ohm or something...

10th June 2002, 13:02	#9
TerAngreal Member Join Date: May 2002 Posts: 1,343	point taken & formula corrected tnx [Bonbon] you try and translate that text after spending a couple of hours learning physics and chemistry ... eat me

10th June 2002, 16:58	#10
TeuS Posts: n/a	I know, duron my blue leds need 435 ohm resistors nearest value: 470 =>NEED THOSE VALUES!