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can i replace the car LED from my clifford car alarm?

Maximus96

Diamond Member
Nov 9, 2000
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i just got a photon 2 microlight and the little thing is so bright, i was wondering if i can replace my clifford LED with a LED similar to the ones used in the microlight...can all LED be used with a 12v battery? and what's the brightest ones? 5600mcd? thanks in advance
 

Harvey

Administrator<br>Elite Member
Administrator
Oct 9, 1999
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Depending on how it is assembled, it may be easier to reduce the current through the LED by replacing a resistor in series with it. If both the LED and the resistor are surface mount devices, you better know what you're doing before you attempt this.

Good luck. :)
 

Maximus96

Diamond Member
Nov 9, 2000
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i don't know what size resistors i would need... how do i find out? only thing i know is that it'll be running off the 12volt car battery...thanks for all the help
 

Harvey

Administrator<br>Elite Member
Administrator
Oct 9, 1999
35,052
29
86
Typical red LED's drop about 2.4 volts. They have different efficiencies (brightness for a given amount of current). You'll probably need 4 - 8 milamps (mA).

Subtracting the 2.4 volts from 12 (the battery) gives 9.6 volts.

9.6 V / .004 A = 2,400 ohms
9.6 V / .008 A = 1,200 ohms

so you want a resistor between 1.2K and 2.4K. Your battery voltage may be higher (up to around 14 volts) so it will be a little brighter than it would at 12 volts, but not much.

One way to figure out what you want is to temporarily tack a 5K - 10K linear pot (variable resistor) in place of the resistor and adjust it for the brightess you want. Then, measure the value you have set, and pick the closest standard value.

Another way would be to get a selection of values, and lightly tack in a couple of pieces of solid wire at the contact points. Cut off resistor leads work well for this. Then you can use clip leads to test different values until you get what you want. Then, just solder that resistor into the circuit. 1/4 watt resistors should be adequate. They're available and cheap. :)
 

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