I’m building an Arduino Mega 2560-based Throttle Quadrant to interface with my Flight Simulator system running FSX. The unit will have 6 potentiometers, 6 toggle switches [on-on and (on) -off-(on)], and 5 annunciators.
Each annunciator will have two LED’s for illumination, and they will be either both on or both off, and their state is to be determined by the output of a single digital pin.
Here is the LED I plan to use alongside an annunciator housing with two such inserted. I have previously used such LED’s singly with Arduino digital pin 5V outputs, in series with a 220 ohm resistor. I have no other information about these LED’s:
I would prefer not to use an external 5 V SMPS.
Now I’m unsure of the best way to wire this up, but I see 3 options:
(1) Connect two LED’s in parallel to each digital pin output. In this case I might need to attach a 220 ohm resistor in series to each LED. I’m uncertain as to whether I might be drawing too much current from the pin in this case.
(2) Connect two LED’s in series to each pin, maybe without a series resistor? Will this work?
(3) Or to be safe, duplicate each digital output, and operate only one LED per pin, with 220 ohm in series. The tradeoff is that I would need twice the number of output pins (10 instead of 5), with a corresponding increase in the wiring mess.
I invite your comments on these options I am considering.