TCCoA Forums banner

1 - 9 of 9 Posts

·
CEO, WT Club
Joined
·
2,648 Posts
Discussion Starter #1
Here is the problem:

The SATC uses 2, size 37 bulbs. Their specs are as follows.
1.26w
90mA
14V

When you switch to blue led replacement bulbs, the dimming mechanism (different intensities for headlights on or off) reverses due to differences in draw.

The LED bulbs are as follows.
.3w
15mA
12V?

Now my question is: what size resistor do I need to run in-line with the LED's in order to have the circuit match that of the regular 37 bulbs? How do I figure this?

-Joel
 

·
Registered
Joined
·
1,544 Posts
....
When you switch to blue led replacement bulbs, the dimming mechanism (different intensities for headlights on or off) reverses due to differences in draw.
Are you saying that the LEDs go on and/or off instead of dimming when you switch the headlights on? Or that the rotary switch doesn't work like it used to?

As long as LEDs have .5v forward biased to them they'll be on. The current level through them is what changes the brightness. Should be the same as a regular bulb unless there's a way to put them in reverse polarity? Do your replacements already have current limiting resistors in them?
 

·
CEO, WT Club
Joined
·
2,648 Posts
Discussion Starter #5
Did you get the specs for the led bulb off the package? Whats the forward voltage? How much voltage does it consume?
I got those specs from the ebay auction that I was going to buy from. I don't know the forward voltage or the ammount consumed.

Are you saying that the LEDs go on and/or off instead of dimming when you switch the headlights on? Or that the rotary switch doesn't work like it used to?

As long as LEDs have .5v forward biased to them they'll be on. The current level through them is what changes the brightness. Should be the same as a regular bulb unless there's a way to put them in reverse polarity? Do your replacements already have current limiting resistors in them?
The SATC temp display, when the headlights are off, is a brighter color. This is so it shows up in the day time. When the headlights are on, they dimmer, for night time. When the LED's are installed... this "reverses". Bright when lights are on, dim when lights are off. I believe they do have current limiting resistors.

Here is the auction with the information I am using. Do I need to ask him for more information? What else do I need?

http://cgi.ebay.com/ebaymotors/4-x-Blue-LED-Light-Bulbs-Instrument-18-37-74-286-2721_W0QQcmdZViewItemQQcategoryZ33713QQihZ025QQitemZ380043197271QQrdZ1QQsspagenameZWDVW

-Joel
 

·
Registered
Joined
·
429 Posts
That doesn't make sense.... I can see the resistor inside from the pic in link, but what else is next to it? I can't tell, it's black. I assume you have them already. Can you tell what it is or post a clear close up pic? The dimmer switch just adds resistence to the curcuit. Same is true with leds. The more resistence the dimmer adds, the led or array of leds get dimmer. No matter if its voltage or current.
 

·
CEO, WT Club
Joined
·
2,648 Posts
Discussion Starter #7
I don't already have them, I am trying to find a solution before I buy.

This has NOTHING to do with the roller dimmer switch. This is about the difference of the headlights ON or OFF. When headlights are on, the NUMBER DISPLAY ON THE SATC is dimmer than when the headlights are off. This is because of the LED's taking a different current. The LED's don't react differently, they just cause the problem.

Solution #1 Wire both the LED's and original bulbs into the socket. Put the LED's in the face of the SATC, leave the bulbs out back (nothing) This will give more resistance, and SHOULD work... I am going to order tonight and hopefully get this figured out soon.

-Joel
 
1 - 9 of 9 Posts
Top