Max97Thump

V=IR
I'm doing Ohm's law and some circuits in my physics class and I figure I'll apply some of this knowledge to an LED project or two...

I need to know how much current, in amps, is going thru the fusebox to do the math and get the resistance and such right, anybody know?

Any other tips for wiring/soldering/mounting LEDs?

Thanks.

friendhasmax

it's easy....LED's usually have a voltage drop across them when current flows through them..so they usually drop about 2.5 volts...so ur electrical system supplies around 13.8 volts......so what u do is subtract the 2.5 volt drop across the LED from the 13.8 volts of the electrical system, and ur left with a voltage of 11.3 volts....now you use ohm's law R=V/I....I in this case is usually the max amperage a LED can handle (usually 20mA) in this case, ohm's law uses Amps and not milli amps, so u use .02A instead in the formula...so u need to find the resistor needed to limit the current that goes to the LED... R=V/I you do the math R=11.3/.02 and you get 565 ohms for the needed resistor value...u can play around with the voltage of the electrical sysem, say you have 12.8 volts instead of 13.8...ur resistor value would change to 515 ohms....if ur LED drops 3 volts in this case u would have a resistor value of 490 ohms....catch my drift?

Max97Thump

Yep...That helped a lot, thanks. I was trying to plug in the current coming from the battery instead of the current going to the LED. What mcd rating should I pick up for interior stuff and maybe...taillights?

Now I just need to learn how to solder.

friendhasmax

www.superbrightleds.com is the place to get bright *** LEDs...i get all of mine from them

soldering is mad easy...but its hard to teach online

Max97Thump

My friend just said he knew and would teach me so I got that covered.

what about viewing angle and mcd rating? 1200, 5000, 8000? I think maybe 8k would be good for taillights and 1200 good for interior applications?

friendhasmax

8000 is very very very bright, 2000 - 5000 should be good for the interior

sk24iam

What's up. I'm doing that stuff in physics also. Where on long island are you? What school?

friendhasmax

if either of u two guys need any help with the electricity and circuits part of physics or magnetism, holla at me cause im in queens, and i go to school for electrical engineering...i could help ya if need be

Max97Thump

Nice, I'm going to school for mechanical engineering - First year.

What is your AIM sn?

I'm in the Hicksville/Plainview/Bethpage area. I go to Fairfield University in CT. What about you?

friendhasmax

my aim: Daillengineer

i go to City College (CCNY)...im finished with physics (including modern physics) if u ever have questions...feel free to hit me up on AIM