Ken Balch, yes - that is correct. Using the GAD 27 makes it possible to control separate circuits with a common dimmer. With the GAD 27, each pot provides a reference voltage back to the GAD 27. The 27 then has 2 lighting control circuits off each - one is a "conventional DC voltage of 0-12 volts and the other is a PWM (pulse width modulation) for controlling LEDs. Each has a separate programmed profile. DC circuits are used by the G3X and GTN for lighting control inputs. For LEDs, the GAD 27 is wired on the ground side. So the "panel lights" circuit comes from one switch, then the red glare shield LED, and to the GAD 27 controlled circuit (ground). The "cabin lights" circuit comes from its switch, then the white glare shield LED, and to the same GAD 27 controlled circuit (ground) - so one dimmer, 2 circuits. The method also allows a baggage LED light to be powered off the same switch (cabin) but grounded through a separate switch in the baggage area and not dimmed.
Also,regarding the screens, I have the G3X and GTN 650 on the same circuit and found it easy to balance intensities. Adjusting the brightness is done in the setup (GTNs have an internal profile). Rather than setting it in the air, I did it on the ground in a darkened hangar.
RV-14A Builder - kit #136, XP-400 Aero Sport Power
N314KC - First flight Mar 8, 2017, 24th in the air, >450 hrs
Sport Pilot (weight-shift control) - Airborne XT912
Dues paid 12/2018
Last edited by KeithB : 02-07-2019 at 07:58 AM.