12 Volt cockpit lighting

[Westozy]

Hi all,

Soon I am going to start the last phase of my simbuild which will be the panel backlighting, wash lighting and also general cockpit lighting. I have a near new 13.2 volt regulated DC power supply and intend to use low wattage auto bulbs. I want to fit dimmers to the MIP panels that work and was wondering if anyone has a circuit diagram on how to build 12v DC dimmers. I have achieved pretty good backlighting on my overhead panel with a few 12v festoon globes but don't know how to make them dimmable. Is this a good way to go or should I be doing it differently? Electrics/electronics are not my field and I would appreciate some good advice.

Cheers in advance, Gwyn

[Tim]

Why not purchase the dash dimmers found in cars? I should think those would work in the sim like they do in a car.

Not sure about new vehicles but I would suspect older vehicles just used a variable resister?

[Tim]

Appears to be many Google hits on "dash light dimmer" or similar.

You may want to consider white LEDs vs incandescent bulbs. LEDs are very low wattage vs 12v bulbs. The incandescent bulbs will get warm to hot also. But, I'm not sure you can dim an LED.

Here is a good site for explaining how to wire LEDs. A current limiting resister is very important.

http://www.theledlight.com/ledcircuits.html

[magicaldr]

But, I'm not sure you can dim an LED.

Pretty sure you can dim LED's, there is a topic on doing so with Phidgets also on the forum I happened to be browsing before reading this one:

http://www.mycockpit.org/forums/showthread.php?p=23797#post23797

May be of use.

[Westozy]

Thanks guys, I am exploring LEDs.

Gwyn

[JBaymore]

Gwyn,

You don't want to use a car panel dimmer. The reason is it is simply a resistor that allows you to shunt some of the power thru it. A resistor disapates energy as HEAT. So you'll be dumping that heat into the enclosure that the dimmer is mounted in.

For LEDs, you actually need a more sophisticated bit of electronics to "dim": them.

No time to write right now..... more in about a week. Teaching an 10 day intensive college class..... close to 24 hours a day ;). Maybe someone else will chime in first on the LED dimmer circuit.



best,

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

[AndyT]

Try this one.
http://www.web-ee.com/Schematics/LED%20Dimmer/LED_Dimmer.htm

[ENKB]

here is a link to a working LED dimmer

http://www.mikesflightdeck.com/led_dimmer.htm


Svein k

[Westozy]

Thanks guys this is great stuff, links like these should be stored on the website somewhere for all to reference. We should build a reference library page, What do you think? Matt, Larry, Trev, Bob?

Cheers guys,
Gwyn

[npbosch]

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?

[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.