well, i got the LEDs to work on the window switches... now it's time for the dash lights. i took apart my dash and it seems that the bulbs are of the filament type (12V/4W). i tried plugging in the LED into the key ring light thing, but i think i fried it. is there any way to get LEDs (which are about 3-5V to go with 12V?

 

i think that you need to put a resistor on either side of the led to bring down the current

V=IR so 12V=(~20mA for led? it should say the specs on the box)*R so R = 600ohms

i havent tried this so... proceed with own risk

 

I second that with one detail - you calculate R = 9/I where I is LED's working current and you're right, for general purpouse LED 20ma is normal and 9 is actually 12V minus LED's voltage(usually 3-4V). It gives approx. 470 Ohm.

Mike.

 

hmm now that i think of it thats the resistor value the led specified on the package! i bought mine at frys they are a bit expensive but they are the smaller t-1 kind.

 

FINALLY i have been trying to figure out what ohms i would need for the resistor... ugh...

excellent

 

Acutally this is the formula...

Ohm = (Mains Voltage - LED Voltage) / LED Amperes, so;
Ohm = (12 Volts - 1.5 Volts) / 0.015 A


I have a 5v leds I bought from rad shack. I put 220ohm resistors in since that was the closest I could find.

12v - 5v then divide that by the LED amps which I forgot now what they were, but when i figured it it came out to 220 or near that. So I hooked them up and wala!! It works!

 

Buy them and just plug them in!!
I ordered mine online at www.radioshack.com

Below from radio shack, their email help is very good!
Some of the LEDs below are 12V
------------------------------------------------------------
Hello!

Thank you for your email.

We apologize for the delay in responding. We have experienced an increased
number of incoming email to our servers.

We carry lots of super-bright and ultra-bright LEDs. We have listed them
for you below.

Red
900-6114
900-6115
900-7168
900-6119
900-8695
900-8700

Blue
900-7859
900-7860
900-7861
900-8005
900-6101
900-7170
900-6102

If you have any further questions, please feel free to write us again.

To better assist you with future questions, please respond to this original
email with the REPLY option, or COPY and PASTE the original email into your
reply (especially America Online Users). Failure to do so, may cause a
delay in responding.

Thank you,

Beth
RadioShack Product Support
http://www.radioshack.com
http://www.radioshack.com/Coupons/Coupons.asp

 

do you know which ones?

 

i bought 2 of these from www.hosfelt.com

6000 mcd 5mm Ultra Bright BLUE LED
Operates on 2.5 - 3 VDC @ 20mA.
6000 mcd typical luminosity T1-3/4 (5mm) Blue. 466nm, 29.5° viewing angle

 

Would you know which one is the ultra bright blue LED? Thank you!

 

i have yet to see 12V leds being sold at radioshack...

i've only seen 3 or 6V ones...

 

Me too...

 

I will say this one more time:

Radio Shack does NOT SELL 12V BLUE LEDs. They SELL AT THE HIGHEST 5V in there online page or at the store. This is only on there blue color.