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11-25-2011, 10:20 PM
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Join Date: Jul 2010
Location: Orlando, FL
Posts: 1,077
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LED post light dimmer
I have four of these LED post lights on my panel. They use the post for the ground connection.
http://www.aircraftspruce.com/catalo...rlightings.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,
__________________
Chris Smith
Maule M5-180C (Sold)
RV-6 O-360 CS (Sold)
RV-4 O-360 FP (Sold)
Full-time in the other type of RV....
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11-26-2011, 12:52 AM
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Join Date: Jan 2005
Posts: 210
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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.
__________________
Kevin Cameron - Fresno, CA - E79
N493DB RV4 Flying IO-360-A1B, 10:1, Straight-Bore cylinders, Gapless Piston Rings, Hartzell CS Prop,
AFS3400-EE, TruTrac DFII VS, Aera 660, GTX 335, GDL 52R,
XM Radio, SL30, SL40, PMA9000EX, MicroTrac 300 APRS
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11-26-2011, 06:48 AM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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The cheap dimmer Van's sells works just fine for LED's.
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11-26-2011, 09:38 AM
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Join Date: Jul 2010
Location: Orlando, FL
Posts: 1,077
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Quote:
Originally Posted by kcameron
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.
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Here is the instal spec for the dimmer from ACS:
http://www.aircraftspruce.com/catalo...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,
__________________
Chris Smith
Maule M5-180C (Sold)
RV-6 O-360 CS (Sold)
RV-4 O-360 FP (Sold)
Full-time in the other type of RV....
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11-26-2011, 09:51 AM
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Join Date: Jul 2005
Location: Bolingbrook, Illiniois
Posts: 254
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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
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Paul
N694BP reserved
RV-6A Very Slow Build!
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11-26-2011, 10:21 AM
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Join Date: Sep 2005
Location: Dothan, Alabama
Posts: 1,487
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Quote:
Originally Posted by Brantel
The cheap dimmer Van's sells works just fine for LED's.
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Ditto. (added words)
__________________
Alton DeWeese
N526RV RV7A Tip Up, IO360 180 W/Hartzel BA prop.
Flying ~950 hours since Aug 2010
N4IDH
Construction Log
?The secret of getting ahead is getting started. The secret of getting started is breaking your complex overwhelming tasks into small manageable tasks, and then starting on the first one.?
?Mark Twain
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11-26-2011, 12:35 PM
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Join Date: Jan 2005
Posts: 210
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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.
__________________
Kevin Cameron - Fresno, CA - E79
N493DB RV4 Flying IO-360-A1B, 10:1, Straight-Bore cylinders, Gapless Piston Rings, Hartzell CS Prop,
AFS3400-EE, TruTrac DFII VS, Aera 660, GTX 335, GDL 52R,
XM Radio, SL30, SL40, PMA9000EX, MicroTrac 300 APRS
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11-27-2011, 07:14 PM
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Join Date: Jul 2005
Location: Bolingbrook, Illiniois
Posts: 254
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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
__________________
Paul
N694BP reserved
RV-6A Very Slow Build!
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