Hello. I am a programmer and haven't done anything with hardware since my physics class a few years ago. Needless to say I've forgotten a few things and after a few hours of searching google and troubleshooting I'm unable to fix my problem.(adsbygoogle = window.adsbygoogle || []).push({});

I am using a fuse tap (it allows me to use a fuse as a power source in my car with a wire coming out the end) with a 5 amp fuse in it. I am using a 12 volt battery in my car. I hooked an LED up with resistors in a parallel circuit. The problem is that the LED does not light up when power is being supplied.

I'm assuming I've done a calculation wrong but I am not for sure about this. It is possible that the fuse tap I bought was bad but i doubt it. I have verified that the LED does work with a simple AA battery test so the LED is not dead.

Here are my calculations: R = Resistance, V1 = my battery (12v), V2 = LED FW Supply (3.2V), Current = LED Amps (20mA)

R = (V1 - V2) / Current

R = (12 - 3.2) / 20mA

R = (8.8) / .02 Amps

R = 440 Ohms

Therefore I bought two 220 Ohm resistors to be able to account for this. They are 1/8 Watt. I did a calculation for this part as well but I was very confused about what the watt rating of a resistor even does.

P (in Watts) = V / R

P = 12 / 440

P = .0272 Watts

Being as this watt rating is very low I am assuming that a 1/8 watt resistor will be able to handle this?

Could the problem be that the Fuse of 5 Amps was never in any of the calculations? Did I miss something obvious here? I have attached a link to how my circuit looks like in diagram form. The wiring is 12 Guage Stranded Hookup Wire (type = AWM) and the LED is a two prong LED (positive and negative), both of which are hooked up to my wire as shown. I currently do not have a ground. This is my first electrical wiring I've done so if something obvious is wrong go easy on me :)

Thanks a ton if you have taken time to read all this, and all help is appreciated!

http://www.screencast.com/t/NzE3N2ViMWUt" [Broken]

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# Fuse Tap Circuit Problem (easy?)

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