Ottawa Fiero Club Forum

Does anyone know if it is possible to just use 600ohm resistors, and Ultra Bright LED's on the Fiero Electrical System.  I don't know how the amp's from the battery will effect it.

Any help would be great.

I don't want to try this because those little LEDs are like $4 a shot.!!

Chris what are you trying to connect i have used 600ohm R   on heated back glass kit to reduce resistance it work well  are trying to hook up computer neon lits ??

one word of caution the do get hot need to protect them like installing them in a metal casing that vented

method i would take is use a adapter use for CD player in sort in hot wire it rather the plugging it to you lighter socket

if you need help let me now

What I am going to be doing is hooking up LED's to the Main Wiring.  This is the for Back window mod I am thinking of.   The LEDS are rated for 3.6V @ 20mA so I need to get the electricity on the wiring right.  600ohm Resistors do it for a standard computer system...but I don't know about the CAR system with the AMPs being so high!

v = I(amps)/R(resistance)

the amount of amps the car has is of no relevance, you need the amperage consomption of the LED.

then plugg in your values in this formula:
R(resitance) = Voltage / I (amps)

Cheers!
Eric

Actually it's

V= I x R

but the resistance formula is right.

I knew the equation...Just didn't know exactly if the AMPs from the battery would mess up my LEDs.   Basically my LEDs are

V =3.6V
I = 20mA
R = ??

12- 3.6 = 8.4
8.4V = 0.02 x R
R = 420ohms...

I just wanted to see though if the amount of amperage the battery had made a difference.  I wasn't willing to risk blowing some expecive LED's over it..

Thanks Guys.

12-3.6???? you need to find a 3V rail, if there are any? what is the max operating voltage?

Did anyone put a voltmeter to the power supply when the car was running.  Usually a car doesn’t run at 12 volts, it runs around 14 volts.  You could also use a zener diode to regulate the voltage if you wanted to be on the safe side but it really isn’t necessary.  But the real shit would be to hook up the circuit in a group of parallel series circuits (I haven’t worked it out so I don’t know if it’s possible).  This way there is less wasted energy (as heat) and you draw less power (not a big deal for this application but it does make a difference on a large scale).  The last thing you want to do is blow a group of 40 $4 diodes.  Also keep in mind that there is usually a .7 voltage drop across a typical LED (check yours, they may be different).

good point, but not a bigg worry, most l.e.d. have a voltage tolerence of +-3V