DIY LED brake lights. Need help.

TitanRev

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TitanRev

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Much neat now...nice....I'm very fond of neat DIY job..It makes those half pass six acc shop guys look like newbie when they see our work...
 

shiroitenshi

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shiroitenshi

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ohms law. Better use the lm7805 linear regulator. just like the lm7809 suggested in smarttag thread.

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shiroitenshi

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shiroitenshi

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i just found out about them in the smartag thread.. i bought them and tried.. they really work! much better than using resistors because can stick a heatsink on them...

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goohtj

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goohtj

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ohms law. Better use the lm7805 linear regulator. just like the lm7809 suggested in smarttag thread.

Sent from my GT-I9100G using Tapatalk 2
Bro, lm7805 is 5v, how you connect? 2 x leds in serie or 1 x led + resistor per set?
 

goohtj

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goohtj

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use a lm7809 to produce 9v n connect 3 x 3v leds in series per bank.
led voltage = 3v so 3 x 3led = 9v so no resistor required.

say 12 leds required for your brake light.
you need 4 banks. each bank draws ~25ma current = 100ma.
lm7809 is 1,000ma ~1,500ma loading. or can easily connect up to 40 banks or 120 leds

input voltage = 11v ~ 35v, power consumption = 2watts (14v x 100ma + some powerloss)

advantage of this DIY.
Cheap (RM3) only.
same led brightness when car is started (14v) or not (12v).

option 2. simpless DIY.
connect 5 leds in series per bank. 5 x 3v led= 15v no resistor required.
brightness is lower.
 

stupidcar

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stupidcar

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use a lm7809 to produce 9v n connect 3 x 3v leds in series per bank.
led voltage = 3v so 3 x 3led = 9v so no resistor required.

say 12 leds required for your brake light.
you need 4 banks. each bank draws ~25ma current = 100ma.
lm7809 is 1,000ma ~1,500ma loading. or can easily connect up to 40 banks or 120 leds

input voltage = 11v ~ 35v, power consumption = 2watts (14v x 100ma + some powerloss)

advantage of this DIY.
Cheap (RM3) only.
same led brightness when car is started (14v) or not (12v).

option 2. simpless DIY.
connect 5 leds in series per bank. 5 x 3v led= 15v no resistor required.
brightness is lower.
bro, i am asking the smarttag one.
 

vr2turbo

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vr2turbo

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use a lm7809 to produce 9v n connect 3 x 3v leds in series per bank.
led voltage = 3v so 3 x 3led = 9v so no resistor required.

say 12 leds required for your brake light.
you need 4 banks. each bank draws ~25ma current = 100ma.
lm7809 is 1,000ma ~1,500ma loading. or can easily connect up to 40 banks or 120 leds

input voltage = 11v ~ 35v, power consumption = 2watts (14v x 100ma + some powerloss)

advantage of this DIY.
Cheap (RM3) only.
same led brightness when car is started (14v) or not (12v).

option 2. simpless DIY.
connect 5 leds in series per bank. 5 x 3v led= 15v no resistor required.
brightness is lower.
Did not know you sifu in this....:driver:
 

goohtj

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goohtj

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Did not know you sifu in this....:driver:
Bro, me only major in Electronic n Computer..

Btw, where 2 source for good super bright led? tried pasar rd - not ideal.
 

stupidcar

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stupidcar

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Bro, me only major in Electronic n Computer..

Btw, where 2 source for good super bright led? tried pasar rd - not ideal.
Bro, eBay. It is cheap. So far so good.
Just be careful before u chose the buyer, see if their ratings are better than 99.8% or not.
If it's less than that, then see the past 6 months, how many complains they got.
 

levin818

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levin818

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It is not a good idea to drive the LED using this method. A proper way should be controlling the current but not the voltage. Reason why is because LED has a very steep V-I curve. A slight changes in voltages will cause a huge changes in current. If the LED has a low side in forward voltage due to manufacturing batch, then it may end up blowing these LED in a short period of time.
 

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