What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

LED post light dimmer

ccsmith51

ccsmith51

Well Known Member
I have four of these LED post lights on my panel. They use the post for the ground connection.

http://www.aircraftspruce.com/catalog/elpages/wheleninteriorlightings.php

I am looking for a dimmer. All the ones that I have found require both the LED pos and neg leads to be connected to the dimmer. They show four connections for the dinner. Power plus and ground, and LED pos and neg.

Two questions:

Can I uses one of these dimmers with the LED neg connected to ground?
If not where can I find a dimmer that will work in my configuration?

Thanks,
 
What kind of dimmer?

I've never seen one like that. I hate to doubt what you said but, given the variety of lights, it seems unlikely that a someone would design a dimmer that needs to break the ground circuit.
 
kcameron said:
I've never seen one like that. I hate to doubt what you said but, given the variety of lights, it seems unlikely that a someone would design a dimmer that needs to break the ground circuit.
Click to expand...

Here is the instal spec for the dimmer from ACS:

http://www.aircraftspruce.com/catalog/pdf/PWM_DimmersLED.pdf

Am I reading it wrong, where it shows two return lines from the LED? Tis also appears to be the nit that Van' offers.

Thanks,
 
Not uncommon

Many LED drive circuits have the LED on the high side of the system meaning between the positive rail and the controlling transistor. In this type of system you CANNOT ground the LED. The only way you could use this circuit with the post leds would be to isolate the post from ground with a fiber washer on both sides of the mounting point and run another wire with a ring lug that contacts the post nut in back and DOES NOT TOUCH THE AIRFRAME anywhere. Digikey and other electronics shops should have fiber insulating washers that are used for various transistor mounting and things like that.
Hope this helps,
Paul
 
I guess you're right. It does require access to the ground circuit of the lights. In my, not-so-humble, electrical engineer opinion, that's pretty lame. I don't like the idea of having to insulate the post light bodies leaving electrically hot pieces of metal protruding into your cockpit. Also, some avionics provide inputs to allow you to the backlight level.

I've been very happy with this one since I installed it 3 years ago:
http://www.periheliondesign.com/egpavr.htm. Besides instrument lights, I've also got the output wired into backlight power inputs of my transponder and audio panel.
 
Might be able to use it yet

Hi Chris,
in looking at the specs it appears it is a low side switch that pulls the low side of the LED to ground. If you add one PNP transistor and a couple small resistors you could change it into a high side drive unit. The parts could be bought at Radio Shack or what ever electronics part place you like for less than $5. If you are interested in how to do this shoot me a PM and I'll send you the information.
Hope this helps,
Paul
 
You must log in or register to reply here.
Back
Top