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GRT Horizon 10.1 dimmer

D Weisgerber

Well Known Member
I have a GRT Horizon 10.1 in my RV8, I just realized that the screen doesn't dim automatically. I read the user manual several times and went through the settings and can't figure out how to make it work, I can manually dim the screen but I would like it to work automatically.
 
My old Sport and current Sport EX didn't/don't dim automatically. Not sure GRT stuff does that...:eek:
 
You "could" auto-dim the screen... The GRT screens which feature analog inputs can use an external dimmer on one of those analog inputs. One "could" fashion a photo-resistor light sensor to accomplish this task automatically. The real down-side is that auto-dimming usually has a fair bit of software tied to it to smooth the input from a photo sensor. By using a photosensor you would see the screen brightness jumping all over the place - likely far more distressing than having to twist the EFIS knob to change brightness.

If you only have one screen, consider yourself lucky. I have three of them (Mini-X, HX, Sport EX) and have to dim all of them manually. Sure, some wise fellow is going to say I should be sharing dimmer settings across the inter-display link. That would be great IF the units shared the same dimmer settings. Unfortunately the cold-cathode fluorescent backlight in the HX produces less light at any dimmer setting than the LED backlights found in the Sport EX and Mini-X so the newer displays have to be set two full brightness settings below that of the HX. I've been after GRT to build in a display dimming offset so that I could get all the displays dimming uniformly using the inter-display link. No-go so far...
 
I have a single adjustable LM317 used as an external dimmer, with separate lines to each efis. I put a fairly sizeable resistor in the line to the brighter display, chose value by trial and error to match brightness to the other. When dimmed they don’t track perfectly but close enough.
 
I have a single adjustable LM317 used as an external dimmer, with separate lines to each efis. I put a fairly sizeable resistor in the line to the brighter display, chose value by trial and error to match brightness to the other. When dimmed they don’t track perfectly but close enough.

That's a terrific idea, Bob. Even better if all the EFIS devices have analog inputs. Darn it, only my HX has an analog input.
 
Thanks for the replies, I think I'll install a LM317 for a dimmer. My 10.1 Horizon does have a photo cell in the front of the bezel. I E-mailed GRT, they informed me that the software doesn't support auto dimming yet.
 
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