LEDs vs incandescent bulbs

[Ethanoost]

Hi
I am building a 737 overhead. So far I have several real 737 panels with Korry type annunciators. Each Korry has 2 28v 387 incandescent light bulbs. These bulbs are a bit power hungry. I counted that I have 98 real Boeing korrys. That means almost 200 bulbs.
The problem I have is interfacing these annunciators. I am using pokeys cards for all the inputs and displays. And pokeys or most other cards (except phidgets) can't cope with high voltage high current lights. I will need more than 5 phidgets cards to run these bulbs.
The options I have is
1: keep the 387 bulbs and use 5 phidgets cards to run them
2: replace the bulbs with led lights and use Wendy s led expansion board to drive them with a pokeys.
3: use relays
4: any other options???

Has anyone has the same problem? How did you interface these parts?
The led replacement light are very expensive. I will need 200 of them.

Any advice will be appreciated
Ethan

[Trevor Hale]

In Honesty..  Buy 2 Phidgets LED64 Cards, and swap the Light bulbs for normal 3mm LED's.   
then your done.

[Ethanoost]

Hi Trevor
How do you swop them? Normal 3mm LEDs won't fit. You need a midget flange base type of led that slots into the space into the annunciator. They cost several dollars each. I need 200 of them.
I'm not sure I understand How to swop them around.
Ethan

[Trevor Hale]

Well, remember nobody can see the back of the Kory.  Just use a little hot melt glue and the led, then solder your wires directly to the led.  Many of us do not use the lamps they come with.
I would have to see the back of what you are talking about, but you can always drill the hole bigger to fit the LED, or make a new backer for the Kory.  its not going to function anymore with the push to test function though if that is what you are trying to get at. But that is something you need to see if the cost is worth or not.

Trev

[Karl737]

I modified my bulbs to leds by soldering the leds into the bulb bases and, as such, they fit straight into the Korrys, 6 packs etc as per a normal bulb. It's a bit fiddly, but doable.

This is what I did:

1) First a simple jig - Grab a piece of square tube (SHS), say 40 mm square x 80 mm long, and drill a hole in it that the bulb will fit into, but not big enough to let the lip of the bulb  through.


2) With the base of the bulb sitting up in the jig and placed on the drill press, use a 1mm or so diameter drill and drill out the solder in the center of the base of the bulb.

3) Now reverse the drill bit and place it back in the chuck, shank end down. Using the drill press literally as a press, push the shank of the drill bit down through the hole in the base you had just drilled: It will then push on the glass, and press it out off the base of the bulb.

4) Clean off some of the glue inside the base - this will give a clean spot to solder one of the legs (in my case, it was the cathode - depends on what interface card you are going to use) of the LED to.

5) Cut whichever leg of the 3 mm led that is going to be soldered to the inside of the base to about 5mm long. Leave the other full length for now.

6) Tin the inside of the bulb base where the short leg is going to be soldered

7) Place a small crank in the short leg - this is to centre the led in the base when it's soldered in - and tin the leg.

8. Place the LED in the base, the long leg going though the hole you drilled earlier.

9) Solder the short leg to the inside of the base - This is the fiddly bit. I set my bulb bases up in a very small vice and clamped by the ridge at the base of the bulb so  the vice did not act  as too much of a heat-sink during soldering.

10) Bend the long leg of the led over where it pops through the hole in the base, trim to leave a little right angle about 1 or 2 mm long and place a blob of solder here. This acts as the centre contact just like the bulb had originally.

It actually doesn't take as long as you think. Obviously you do it in bulk steps, like pressing out the glass in 50 bulbs then moving on to the next step...

Anyway, that's what I did. Hope the post is of help...

Cheers,
Karl

[727737Nut]

98 Korry's = 7.82 Amps give or take a few mA during 'light test'  Doesnt seem to power hungry to me      Bulbman.com sells these bulbs cheap.  My advice just like in your other post on same subject, keep it simple, keep it original, buy the relay cards or NPN transistors.

Rob