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Panel dimmer or not? (Garmin)

iamtheari

Well Known Member
I am planning to use the G3X Touch in my RV-14. The devices actually visible on the panel will be a 460 (PFD) and a 465 (MFD), a G5, a GMC 507 autopilot control panel, and a GTN 650 navigator. Power will be supplied by a VP-X Pro. I just got the fuselage kit today, so of course I have spent the past month planning out the panel wiring harness.

My understanding is that the screens I will be sitting in front of all have an auto-dimming feature based on ambient light and that wiring up a manual dimmer circuit is optional.

For those who have similar equipment, do you have a panel dimmer? If so, do you feel it was worthwhile? If not, do you wish that you had one?
 
I am in the same place and my question/research has shown that they are all self dimming and no external dimmer is needed. I hope I have not got the wrong info and would love to hear confirmation on this.
 
I am wiring up the dimmer. My research on Van's seems to show that there are times the sensor my not sense the light properly (such as low sun angle) that may cause more light on the screen but not necessarily the sensor and it might be to dim. Nice to be able to reach over and adjust it where you like it. Just another data point.

Jay
 
I install dimmers for the big screens and GTN units on every panel upgrade I do because that is what I personally prefer, when flying at night I like my panel stuff at minimum brightness levels and going into a menu to do that is not a priority, just easier to twist a knob and adjust to your liking.
 
I wired the dimmers but still use the auto dimming feature on the 460's, G5 and GTN 650. They all work fine but I do find the G5 reacts slower than the others. It takes several keystrokes in the menus to change over to the manual dimmers. I wired mine through the GAD 27.
 
Virtually all Garmin panel-mount units feature photocell-controlled lighting that can be profiled. In practice, it works very well. One thing to remember, however. The Garmin panel-mounted audio panels need a dimmer input for the backlighting, so if you have one you should install at least one dimmer. You could also provide a fixed voltage input to it and switch a resistor into the circuit with the nav light switch for a dim position.
 
Thanks for the tips. A thought I had is that the only time being able to see what's on the panel would become a true safety of flight issue is when the natural horizon is not visible. For me that means IMC or night. (Mountain day VFR could qualify as well but I'm not a mountain pilot...yet.) At night, the photocells will almost certainly figure out it's dark. That leaves IMC.

Has anyone had issues with the photocells while flying in the clouds or other IMC?

Another factor: Do the certified equivalents of these Garmin products require dimmer knobs in a conforming installation?
 
Not so for the GMA245:

Photocell dimming circuitry automatically adjusts the brightness of the annunciators.
Backlighting is controlled by the aircraft lighting bus inputs if the lighting bus is connected.
If the lighting bus is not connected, backlighting is controlled by the photocell.
 
I install dimmers for the big screens and GTN units on every panel upgrade I do

Walt, if not too much to ask, can you provide link to the dimmer unit you use?

Can any of the Garmin equipment be configured to be a dimmer "master", i.e. to provide voltage output from the photocell for the other units and non-Garmin equipment?
 
Walt, if not too much to ask, can you provide link to the dimmer unit you use?

Can any of the Garmin equipment be configured to be a dimmer "master", i.e. to provide voltage output from the photocell for the other units and non-Garmin equipment?

I just use 10K pots, simple and reliable, one for the G3X and one for the 650. I believe the GAD27 can be used as a dimmer master to control other stuff.
 
Not so for the GMA245:

Photocell dimming circuitry automatically adjusts the brightness of the annunciators.
Backlighting is controlled by the aircraft lighting bus inputs if the lighting bus is connected.
If the lighting bus is not connected, backlighting is controlled by the photocell.
They changed that, then, which is good. The earlier audio panels had no photocell backlighting control available.
 
It's not a big enough nuisance to make me change it, but if did have an opportunity, I would put a panel dimmer on my Garmin 430W. I do have the photocell ramp, offset and minimum values tuned. Night flying levels need to be remarkably dim.
The nuisance time for me is sunrise which I fly quite often. Just before the sun breaches the horizon, but the sky is considerably lighter, the garmin is too dark. That period lasts maybe 15 minutes max. I guess I might be able to play with the offset or ramp settings some more but it would be nice to just twist a knob.

EDIT Like Walt, I do have a couple of home made dimmers in the cabin. They are for LED floods that illuminate toggle switches and separately a handful of Nulites. On each I used a 50K pot, a 5K resistor and an LM317T voltage regulator. All built and glued to the pot. Gives a 10 to 1 turn down ratio. I think I have seen example schematics of this simple circuit on EAA or elsewhere. The LM317T package usually has it too.
 
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Dimmer

I just did my Panel with Dynon and Garmin GPS. And I'm using the Advanced Control Module which is similar to VPX. Quick Panel by Advanced. But I also have lighted rocker switches. At first I had the rocker switch lights wired to the dimmer from the ACM (VP-X). It dimmed the rockers too far, too dim, almost off. It dimmed the Dynon screens appropriately. There is no software setting to set the dim level different between screens and the rocker lights. So I have a dimmer for other lighting. Now the screens can dim the way they want to and I can manual dim the rocker switches and any other internal lighting I decide to add. I may add a ceiling light, or floor lights and they will come off the dimmer switch.

Yes do the dimmer.
 
Dimmers

Well. I almost had my panel ready to install until this thread popped up. Hmmm. Thinking if I should add dimmers now. G900X. I think I have a couple potentiometers laying around somewhere.
 
I have a full Garmin panel. I chose to use the GAD 27 with 3 input pots (10k as Walt described). The GAD 27 has 6 dimming circuits (customizable) controlled from the 3 inputs - 3 with voltage control for screens inputs (G3X and GTN 650 in my case) and 3 with pulse width modulation for LED circuits. I use Pot 1 for screen, Pot 2 for switches (LED lights) and buttons (such as GMA 245 audio panel), and Pot 3 for a glareshield-mounted LED strip for both panel lighting (red) and cabin lighting (white).

As others have said, sometimes the photocell just doesn't get it right (dusk and dawn in particular, and during setup before taxi in the dark). Also, the custom profiles can be set to allow an "off" setting allowing me to turn off all panel switch lighting and the glareshield strip during night cruise.
 
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