LED guru's Question
Thread Starter
Racer
Joined: Jan 2003
Posts: 428
Likes: 0
From: Eagle River AK
St. Jude Donor '10, '13
LED guru's Question
I have a HU mount for my head unit with the LED lettering above - right now it is hooked up to my dimmer control but it is still to bright for night driving. If I turn down the display to make the HU mount dim enough the gauges are to dark - so my question is what can I do to dim the HU mounts LEDS either manually or with a resistor? What am I looking for as far as resistor size ?. Other suggestions would be appreciated.
Thanks,
Steve
Thanks,
Steve
Le Mans Master
Joined: May 2006
Posts: 5,987
Likes: 18
From: DuBois PA
St. Jude Donor '11-'12-'13-'14-'15
Assuming they are wired in seires, the easiest way would be to solder a resistor into the power lead for the LEDs, a variable resistor would allow you to fine tune the light output to match the rest of your lighting.
Something like this at Radio Shack;
http://www.radioshack.com/product/in...entPage=family
Something like this at Radio Shack;
http://www.radioshack.com/product/in...entPage=family
Last edited by tstar; Jul 6, 2008 at 06:48 AM.
Burning Brakes
Joined: Jul 2004
Posts: 1,172
Likes: 71
From: MA
You can try a resister but don't go below the threshold voltage needed to light the LEDs. The one that I just installed in my gauge pod requires 10V to light (it is a 12V LED). A 12V led typically draws 25ma of current. So you can calculate the size resister by using E=IR. A 12V LED has a built in resister valued at approximately 4800 ohms (calculated using E=IR with E=12V and I=25ma) so you have to factor that in to the equation.
I installed a 1/2 Watt 1000 ohm resister in my circuit and it didn't seem to dim the LED because the upper threshold voltage of the LED was 13.5V (charging system can put out 14.7V) and i didn't seem to dim the LED.
Now I am not an electrical engineer (mechanical by training) and a LED id a diode. If anyone is an EE please step in and comment.
I installed a 1/2 Watt 1000 ohm resister in my circuit and it didn't seem to dim the LED because the upper threshold voltage of the LED was 13.5V (charging system can put out 14.7V) and i didn't seem to dim the LED.
Now I am not an electrical engineer (mechanical by training) and a LED id a diode. If anyone is an EE please step in and comment.
