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  #1  
Old 12-29-2018, 01:38 AM
SPark SPark is offline
 
Join Date: Sep 2018
Location: Sydney Australia
Posts: 7
Default Dimming the G3X

Hi there,

I'm currently building a RV7 with a G3X suite. I would like to manually dim the G3X 460 Display, the G5, GTN625, GTR200 and a few LED Light strips.

If possible I would like all the LRUs on one dimmer and the LED lights on another.

My question is, can I dim the LRUs with a simple Potentiometer or do I need other equipment?
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  #2  
Old 12-29-2018, 06:24 AM
pilot2512 pilot2512 is offline
 
Join Date: Aug 2007
Location: Spring, TX
Posts: 485
Default

the garmin components should be done with a potentiometer, its the LED lights that need a PWM (pulse width modulator) to dim them.
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  #3  
Old 12-29-2018, 06:45 AM
Walt's Avatar
Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 6,014
Default

You might want to consider installing a GAD27 controller, very versatile box for light control, it also does some cool other functions like controlling trim/flap/ldg light wig wag.
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Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1900+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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  #4  
Old 12-29-2018, 12:16 PM
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g3xpert g3xpert is offline
 
Join Date: Sep 2010
Location: Olathe, KS
Posts: 3,014
Default

As Walt mentioned the GAD 27 is a great unit if you are building an aircraft with the G3X Touch. It is a smart dimming controller which has multiple PWM and voltage reference outputs to connect to your different avionics. Using the GAD 27 you can individually balance each circuit and use one, two, or three pots to control these circuits.

In addition, the GAD 27 has a flap controller, extra discrete inputs, wig-wag controller, and trim mixing (to allow you to easily wire your stick grips for trim control)

All of the Garmin LRUs listed above except for the G5 have the lighting bus. The G5 is primarily controlled by the photocell, but also has a manual backlight mode. The G5 was designed this way to bring independence to your backup instrument.

Thanks,
Levi
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  #5  
Old 12-29-2018, 01:19 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,987
Default

Quote:
Originally Posted by g3xpert View Post
As Walt mentioned the GAD 27 is a great unit if you are building an aircraft with the G3X Touch. It is a smart dimming controller which has multiple PWM and voltage reference outputs to connect to your different avionics. Using the GAD 27 you can individually balance each circuit and use one, two, or three pots to control these circuits.

In addition, the GAD 27 has a flap controller, extra discrete inputs, wig-wag controller, and trim mixing (to allow you to easily wire your stick grips for trim control)

All of the Garmin LRUs listed above except for the G5 have the lighting bus. The G5 is primarily controlled by the photocell, but also has a manual backlight mode. The G5 was designed this way to bring independence to your backup instrument.

Thanks,
Levi
Just wanted to confirm that the G3X dimmer input is looking for variable voltage from the potentiometer.

Larry
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  #6  
Old 12-29-2018, 01:32 PM
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Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
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Quote:
Originally Posted by lr172 View Post
Just wanted to confirm that the G3X dimmer input is looking for variable voltage from the potentiometer.

Larry
Yes that's correct.
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Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1900+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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  #7  
Old 12-29-2018, 09:43 PM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by Walt View Post
Yes that's correct.
Thanks Walt.
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  #8  
Old 04-12-2021, 10:53 PM
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mfleming mfleming is offline
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 674
Default So I thought I would ask the question here...

instead of starting a new thread.

Garmin says there can be no more than 10mA per pin on the GAD 27.
Garmin also doesn't publish the milliamp ratting for all of their displays. I did find the GDU-4XX are 1mA per unit for the lighting bus but could not find the milliamp rating for anything else.

Seeing that I have 7 units with lighting buses and want all of them on one dimmer...I don't want to exceed the max 10mA draw on one pin and screw up the GAD 27.

Any insights??
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Joseph, OR
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RV-7 Slider #74572
Started 11/2016
Empennage completed 11/2016 (sans fiberglass)
Ailerons and flaps completed 3/2017.
Wings completed 12/2017
Started on QB fuselage 01/2018
Sliding canopy mostly completed 10/2020
Wiring completed
Avionics harness build in progress
Donated for 2021 and so should you
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  #9  
Old 04-12-2021, 11:11 PM
rapid_ascent rapid_ascent is offline
 
Join Date: Mar 2008
Location: Dublin, CA
Posts: 1,455
Default

Michael,

I think you can actually use multiple outputs that are controlled via a single input pot. That allows you to split up the units to different outputs. To be honest I haven't looked at this a ton. I think in general though the DC outputs normally only provide a reference voltage and very little drive current is required. You can also use the PWM outputs for cases where more current is actually required. I think those outputs can drive 500mA.
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  #10  
Old 04-12-2021, 11:44 PM
mfleming's Avatar
mfleming mfleming is offline
 
Join Date: Sep 2016
Location: Joseph, Oregon
Posts: 674
Default

Quote:
Originally Posted by rapid_ascent View Post
Michael,

I think you can actually use multiple outputs that are controlled via a single input pot. That allows you to split up the units to different outputs. To be honest I haven't looked at this a ton. I think in general though the DC outputs normally only provide a reference voltage and very little drive current is required. You can also use the PWM outputs for cases where more current is actually required. I think those outputs can drive 500mA.
According to the G3X tech I talked to today, I can split up the displays to more pins but that means more dimmer controls. Iíd really like to just have on dimmer control for the displays. Youíre correct that the PWM outputs can be used for powering LED strip lighting.

You are also correct that itís just sensing voltage running through the dimmer switches but they canít have more than 10mA run through an individual pin, or to put it another way, through a single dimmer switch.

My dilemma is how to find or calculate the individual displays milliamp draw.
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Michael Fleming
Joseph, OR
sagriver at icloud dot com

RV-7 Slider #74572
Started 11/2016
Empennage completed 11/2016 (sans fiberglass)
Ailerons and flaps completed 3/2017.
Wings completed 12/2017
Started on QB fuselage 01/2018
Sliding canopy mostly completed 10/2020
Wiring completed
Avionics harness build in progress
Donated for 2021 and so should you
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