When moving the gear lever up and down, the gear indicator lights are changing as well. For most light aircraft, there are three green gear down and locked indicators, and one red gear in transition indicator. Although the flightsim screen will also show them, I found it handy to have real lights next to the gear handle as well.
From the sim, you can check the light sequence and timing, and with a small circuit driven from the gear lever switch, you can make the four lights behave in the same manner.
Gear up/down lights sequence
Gear lights circuit:
The above circuit shows the gear lights driving circuit and the connection to the gear lever switch. In shown position, the gear switch output is low. This should correspond to gear up position. The three upper LEDs and the red LED are dark.
When the gear switch is flipped to gear down position, the
upper one-shot gets triggered, and produces a positive pulse of
about 4.7seconds at the Q output. (determined by R*C of
the upper one shot timing components) This pulse drives the lower
transistor and the red LED will light for 4.7 seconds. At the
When the gear lever is again pushed in the gear up position, the switch output goes low, and the green lights go out. At the same time, the lower one-shot is triggered, and its Q output sends a high pulse of 4.7seconds to the red LED driver transistor.
You can change the gear transition time by changing the 470k resistor value or the 10uF capacitor value of upper and lower one shots: Upper determines up à down time, lower determines the downà up time.
(For info on the ICs, see the Elevator Trim section)
Gear light indicator components and wiring setup: