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Leds... wire series?

VL Berlina 5speed

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just bought my self some blue Leds and resistors, now im not positive on how to wire them,
if i wire it in series do i just use one resistor at the start of the series or do i put one in between each led?

im putting three leds in to the circuit which are all blue, i was told i need this resistors that the dude gave me but im not sure if he under stood me about putting them all in the same series, he said they were something like 550's, are these ok?
 

VL Berlina 5speed

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just checkd the colours up and its actually 560

colours on the resistor are,
green....blue...brown...gold
...5........6.........0......0.1


buggar, posted in the audio section, if a mod could move it to electrical it would be much appreshated, cheer

cheers 4 moving it ads:thumbsup:
 
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VL Berlina 5speed

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cheers for that FXST01,
just 2 more questions, what is the highest volts u recomend put into a Led
2volts? or higher? (each)

and cable wise dose it matter if i use to big of a guage cable for this, as ive got a spool off some thinker stuff that i use for all my wiring and just unsure if it would supply to much for the LEDs
 

FXST01

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With LEDs you are talking mA to power them, not volts.

You need to know what volts you are using and what mA the leds require to run, then the below link (bottom calculator) will figure out the Ohms need for your resistor.
e.g. 12 volts power, LEDs use 20 mA so the resistor needs to be 600 Ohms. (assuming only using one LED)
e.g. with 4 LEDs running in series, the 12 volts will be divided amongst them so, 3 volts power, LEDs use 20 mA so the resistor needs to be 150 Ohms.

http://www.mcsquared.com/ohmframe.htm

As for thicker wire, you'll only run into problems when using smaller than required wire, as it will heat up too much (thats bad). You'll be fine using thicker wire.
 

VL Berlina 5speed

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well ive came up with many results:b:
but these are the 2 i cant figger out, which one should i use, the 12 volt rating or 13.2? would i take the 13.2 as its higher there for safer, as if i was to use the 12volt setup and the motor was running, it would produce the 13.2 volts and frie the LEDs

1st result

Supply Voltage : 12
Voltage Drop Across LED: 3.2
Desired LED Current : 20mA
How many leds connected: 3

Calculated Limiting Resistor: 120 ohms
Nearest higher rated 10% resistor: 120 ohms

second result

Supply Voltage : 13.2
Voltage Drop Across LED: 3.2
Desired LED Current : 20mA
How many leds connected: 3

Calculated Limiting Resistor: 180 ohms
Nearest higher rated 10% resistor: 180 ohms

do these sound right?
cheers for putting up with my stupidness, its just im not so fond of the LEDs and risister then other stuff
 

vzsv8

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Calculating the resistor

As already said the resistor is only there to limit the current.
A led drops about 2 volts across it. (every colour is different, red leds are 1.7 Volts) So if you are running from 14 volts than the voltage is shared 12 volts across the resistor and 2 volts for the led.
So if we settle for 20mA through the led we use Ohms Law to work out the required resistor (you did listen in Science class, didn't you?).
R=V/I R=12/0.02 (20mA is 0.02A)
R=600Ohms

To run the same led off 5volts, resistor voltage is 5-2=3 Volts.

R=V/I R=3/0.02
R=150 Ohms

Hope this helps, Steve
 

VL Berlina 5speed

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vzsv8 said:
As already said the resistor is only there to limit the current.
A led drops about 2 volts across it. (every colour is different, red leds are 1.7 Volts) So if you are running from 14 volts than the voltage is shared 12 volts across the resistor and 2 volts for the led.
So if we settle for 20mA through the led we use Ohms Law to work out the required resistor (you did listen in Science class, didn't you?).
R=V/I R=12/0.02 (20mA is 0.02A)
R=600Ohms

To run the same led off 5volts, resistor voltage is 5-2=3 Volts.

R=V/I R=3/0.02
R=150 Ohms

Hope this helps, Steve
i wasnt teached s*t in science, electronics was a option but didnt take it up only did a little elctronics a couple yrs ago and i 4got now :eek:

how about i post the details on the LED i have and if you wouldnt mind could u figger it out for me it would be much appritiated

8000mcd Super blue LED
foward voltage- 3.1>3.4
condition- 20mA
i wanting to run three in a series so what resistor is needed?

is this it,
three blue LEDs 3.3 x 3 = 9.9
total suplyd volts 13.2 - 9.9 = 3.3
3.3 / 0.02 = 165
=R165
?????
 

FXST01

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Working off 13.2 volts, with a voltage drop of 3.3 volts across the LED and 20 mA to light up the LED, time 3 in the series, you would need a 180 ohms resistor.

So pop down to Dick Smiths with 5 cents and get a R1056 1/4 watt 180 ohm resistor.

This is how i would do it.
 

VL Berlina 5speed

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cheers to FXST01 and vzsv8 for helping to teach a kid that forgot his science and elctronics from yr 9 schooling,

its all good now and working got some pics posted in my ride section the links here and the pics are like the last post,
http://forums.justcommodores.com.au/showthread.php?t=36358&page=2

cheers 4 the help:thumbsup:
 
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