What did I do wrong???

[ThrustTugKeith]

I bought some 12 volt LEDS to hopefully use in lighting in both boats. They are pretty large, but when I hooked them up to 12 volts, they explode. :eek: I'm what you call " Electrically Retarded" :rolleyes: ...any ideas on what I did wrong?
Please submit all answers on a TOTALLY basic theory (you've been warned).

Scott (still picking glass outta my arm) :censored:

[Rex R]

two things spring to mind, 1) over voltage or 2) hooked em up backwards.

[patmat2350]

Dear Scott who won't read our voluminous prior postings on LEDs:

"LEDs are not light bulbs!"

They must have resistor in series with each one to limit the current... otherwise, they are like little short circuits and go "poof".

BTW, there's no such thing as a 12v LED in the way that a light bulb is rated at 12v- it means something else.

More later.

[patmat2350]

OK, start at post 10 at:
http://www.rcgroups.com/forums/showthread.php?p=6476115

[frieslander]

12 volt????? More like 1.2 volt I bet.

[ThrustTugKeith]

<<Dear Scott who won't read our voluminous prior postings on LEDs:>>

Thanks, Pat, I wont ask again. Didnt know the threads were there. In the future, try to treat the handicapped better. We all arent Electrical Engineers like yourself. Ill use regular bulbs, the hell with it. Sorry to be a bother.

[patmat2350]

I will only beat you about the head and kick out your crutches if you give up!

But... if you can find some place that sells resistors, get some with values between 600 and 1000 (1k) ohms, 1/2 watt rating- these will let you run most any LED (with ANY voltage rating) directly off 12v. Just wire the resistor in line with the LED, to either side of it (+ or - side). THEN you can connect it like a light bulb. If it doesn't turn on, just reverse the wiring, no harm done.

If running on a lower voltage, a lower value resistor is called for. The calculator referenced on the other pages will tell you which.

Mean ol' Pat

p.s.: And PLEASE, I'm a mechanical engineer... I only resort to electrons when clock springs and steam won't do the job!

[LONGBIKE]

Regular bulbs looks more reallistic anyway. LED's are whay to brite for the small scale!

[jimmyflappers]

diodes (LEDs) will be a lot less juicier, no idea what boat or batteries you have, so I don't know if it's even relevent to you, just thought I'd throw that in the mix.

If you are worried about battery life use a coulple of your diodes (but make sure you put a resistor in series with each one).. *edit* a 1k resistor should do you fine)

If battery life isn't much of an issue use small bulbs

if "resistors" and "series" mean nothing to you PM me and I'll explain outside of this topic

Jimmy

[patmat2350]

Ah, but with the right resistor, you can make an LED as dim as you like!

They have other issues though-
- "White" LEDs are bluish, not yellowish like incandescents. In the other post, it was mentioned that an orange coating (like fake stained glass paint) can take the blue tinge out.
- Standard LEDs are very directional, like a flashlight. Good for mounting in a spot light, lousy for nav lights and such which want "all around" light. Some have had luck with frosting and flat-spotting the end, not me though. The new Christmas lamp LEDs (see other thread) do a much better job if they'll fit your application.

Plusses:
- If set up right, they'll last forever, no need to make "servicable" installations.
- Very low current drain compared to incandescents.

Pat M

[Prins Willem]

17 odd years ago when I built my 36" tug I bought yellow 5 volt LEDs from Radio Shack for deck lights. The package had a ballast resistor recommendation right on the back. I then used Miniatronics grain of rice incandescent bulbs for the towing lights. The color and intensity made the towing lights distinguishable from the deck lights.

This reminds me. I have to rewire the lights in this tug. Thanks for making my to do list longer. :D

[MILLERTIME]

Look here, BOOKMART IT.
LED calculator
http://led.linear1.org/1led.wiz


Don M.

[more coffee]

just for my own knowledge
if say 2 leds are in parrell, one resister or 2, what about series parrell , or just series.