Thread: Fmc Led Backlighting Help !
10-19-2008, 04:31 AM #1
Fmc Led Backlighting Help !
hi all need a some advice regarding backlighting for my opencockpits fmc.
Im using the output card from opencockpits which gives 50 volts per output and 500 ma. And i need to run around 20 x 3mm or 5mm leds for backlighting . Can anyone tell me what leds i should buy (as in votages) and resistors plus how i should wire them serial or parallel and how many outputs to use .
Im a novice with this.
10-19-2008, 04:28 PM #2
10-19-2008, 04:48 PM #3
10-19-2008, 04:56 PM #4
maybe jou can have a look at:
but why are you using the output card for backlighting?
why not using 12V from a PC powersupply?
I use bright green leds for my cdu backlighting (see my site, pictures)
the leds I use have a voltage drop of 3.8V so I connect 2 leds in series with a resistor of 220 ohm, you can connect several of these combinations parallel to your powersource.
powersource 12V - (2 x 3.8V drop) = 4.4V
divide that by the led amp (usualy 20mA), this gives you 220 ohm as a resistor.Regards,
(my hobby: http://777simulator.nl)
10-19-2008, 05:34 PM #5
thanks for the reply the reason i was going to use the output card is because i thought if i connect all the backlighting this way i can control the dimming of the light through the software ie sioc.
what do you think?
10-19-2008, 05:43 PM #6
- Join Date
- Jan 2007
- Perth, Western Australia
HERE. Very cheap and plenty of them. And as already mentioned, no need to waste your output card just use a 12v power pack with resistors For a good example of the building process and resistor calculations have a look HERE.
EDIT. I just read your previous reply. Yes the ability to adjust brightness via SIOC is a good one and in fact used by Opencockpits with their backlit EFIS unit. Just be mindful that given the number of LED's you need to backlight a panel, you'll quickly reach the limit of outputs on the card. If you're using it just for the FMC then you're fine.
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