||In order to see the meters, switches and controls during
night flying, all cockpits have cabin lighting systems. Many cockpits have back-lit
switches and controls, to clearly identify each function.
In my simple and modular cockpit, the controls and switches are not backlit, but I have added a general lighting system that lights-up the controls from a place just below the scenery visual system.
For simple low power lighting with adjustable light intensity, I have used white and yellow (amber) color LED strips, driven by two separate LED drivers, each with dimming capability.
The LED driver schematic is shown below. The Pichler white and yellow LED
strips each consist of 18 sections, where each section has 3 LEDs and a
balancing resistor. All 18 sections are connected in parallel. The LED
driver is build around Richtek RT8470, which is a hysteretic switch mode
step-down converter, capable of delivering max 1A of current. The LED strip
voltage is around 11V, and input voltage needs to be around 15V. Current for
the amber LEDs was set at 300mA total, and for white at 400mA total.
The RT8470 ADJ input can be driven with a DC voltage ranging between 0.25V (zero current) and 1.3V (max current). The dimming function It actually chops the LED current at a rate of 300Hz, chopping duty-cycle determined by the ADJ DC voltage.
The two potentiometers can be used to separately adjust the white and
amber LEDs. For night flying, I adjust the color to amber.