G3X Lighting Bus Dimmer

MK77 · #1 10-21-2013, 05:17 PM

Hi All, Anybody know if the Garmin G3X lighting bus input has issues with PWM dimmers? I've heard some EFIS displays don't like the PWM as it causes flickering.

Matt

Bill.Peyton · #2 10-21-2013, 07:29 PM

I had a problem with the flicker and ended up just using a potentiometer.

MK77 · #3 10-21-2013, 07:51 PM

Good to know, thanks for the info Bill!

BillL · #4 10-21-2013, 08:04 PM

Ask The Stein guys, they put one in my panel, but I don't know its' principle of operation.

If I find it, I'll post. BTW- 60 hz refresh on computer screens gives me vertigo in about 3 minutes. 75 or greater and I can not see it. If the PWM frequency is high enough you won't see flicker anyway.

Bill.Peyton · #5 10-21-2013, 08:05 PM

Good point...not all PWM dimmers operate the same

g3xpert · #6 10-22-2013, 11:47 AM

Hello Matt,

The low-frequency PWM output from most dimmer units is designed to drive a string of light bulbs, which don't care too much about input frequency. Unfortunately this doesn't always play well with modern digital avionics, no matter who the manufacturer is. In my airplane I installed a LC-50 dimming unit, which has both PWM and analog voltage outputs. The PWM outputs go to my LED cockpit lights and the analog outputs go to the lighting bus inputs on my various avionics. For this purpose you can use any dimmer that has an analog output, or even a simple potentiometer - remember that this signal doesn't actually have to supply any power, it's just supplying a voltage reference to a computer's input pin!

good luck,
- Matt

MarkChristopher · #7 10-23-2013, 06:45 AM

Matt, I have the same setup with the LC-50. I have 5 Garmin devices that I need to dim. Is it possible to combine all those into a single LC-50 input (AO1 for example) or will it end up drawing too much current?
Thanks,
Mark

g3xpert · #8 10-23-2013, 07:11 AM

Quote:

Originally Posted by MarkChristopher

Matt, I have the same setup with the LC-50. I have 5 Garmin devices that I need to dim. Is it possible to combine all those into a single LC-50 input (AO1 for example) or will it end up drawing too much current?

Mark,

Your setup is essentially the same as I have on my airplane, where it works great. As I said above, the lighting bus inputs on modern avionics draw only a tiny amount of current, since the lighting bus voltage is not directly driving the display backlight. For further detailed information I would recommend checking with the manufacturer of the LC-50 unit.

- Matt