12 Volt cockpit lighting

[Michael Carter]

You will eventually burn up a pot if you run it long enough with enough voltage or current.

You can rarely use a pot as a rheostat. They are not exactly the same animal.

[Westozy]

Hello to all,

Till now I use a light rope for my overheadpanel. Works nice, but takes a lot of space , so I will experiment with high intensity white leds.

A normal led will need around 120-150 ohm as a resistor. (there are alculators available for this).
As I increase the resistor value, less current will go through the led and it will dim.

Suppose that 300 ohm gives a nice minimal brightness.
Then I use a 120 resistor in serie with a 180 ohm variabel reisstor (potentiometer). So I can turn a knob and change the resistor value between 120 and 300 ohm.

What is wrong with that setup? I wil experiment with this. Is there a reason that the above links show more complicated solutions?

Looking forward to seeing your results Norbert!

Gwyn

[JBaymore]

What is wrong with that setup? I wil experiment with this. Is there a reason that the above links show more complicated solutions?

norbert,

See my comment above about resistors and heat. You'll need a amperage (or wattage) rating of the variable resistor (potentiometer) that can dissipate the total current for all of the loads (LEDs) that you will have on the circuit.

All of that current is always flowing in the circuit....either through all the LEDs OR through the pot or through a combination of both, depending on the brightness setting you are running. The LEDS are pretty efficient at converting the energy to light and generating little heat ... the pot is only able to dissapate the energy as HEAT.

So if you can stand having a certain amount of heat being generated in the enclosure...... it will work. BUT.... make sure that the airflow around the pot is moving the heat off the pot... or it'll eventually burn up / out.

When the LEDs are fully dimmed... you are running a little mini toaster in your panel.

best,

................john

[brissydave]

leds...are bad you kids...mmmmkay?
too white...hard to get the correct fingernail pinky glow even with filters.

incandescent 12volt indicator globes run from one or two atx supplies give the most beautiful backlight possible. i get 350 watt brand new atx supplies for 35 bucks au.

i used about a dozen or something to do my overhead. they are set back a couple of inches the further back the better....it really is the closest thing to the fds ibl stuff. the placement is not critical at all. i have messed with christmas lights...leds....garden lights...you name it. 12 volt 21 amp for overhead...12 volt 5 amp for mip....on the heat side of things....suprisingly there is very little. i left my overhead lights on all night accidentally (flying pissed again) and in the morning the panels were all cool. i have considered putting a few pc fans in the overhead box running off the same supply....but it doesnt seem to need it. i wouldnt have a clue about power usage. maybe they are bad....maybe my seven pc's are bad too!

i havent installed a dimmer yet....but really want to get it done.

[npbosch]

John, thanks for the advice. I got your explanation and will not further investigate that way.