Real boeing annunciator and pokeys

[Ethanoost]

Hi
I am experimenting with a pokeys 57e card. Thinking of wiring up my entire overhead using them. They seem very versatile.
I have a question though
Will I be able to wire the 28v annunciator bulbs found in real boeing Korry type switch lamps and FDS panels to a pokey card? Will I need a relay or something? These light are power hungry?

Thanks for the help
Ethan

[fly_ebos]

1 Korry at 24v is about 0,5A. Way too powerfull for a Pokeys.
Safest way is a phidget 0/16/16, but you will need a lot of them and they dont come cheap either.

Thomas

[727737Nut]

Stay away from the overpriced Phidgets.  Driving the real Korry's is easy!  Use the PoExtBus relay card.  You can have 80! 28V outputs   Or even cheaper, use a resistor and NPN transitor as a homemade switch.   Way cheaper then the phidgets
Rob

[Trevor Hale]

LOL  Rob has the most experience with this.  Listen to him...

[727737Nut]

1 Korry at 24v is about 0,5A. Way too powerfull for a Pokeys.
Safest way is a phidget 0/16/16, but you will need a lot of them and they dont come cheap either.

Thomas

Not sure what Korry's you tested but all mine in my 737 pull 60 to 80mA each not 500mA like you say. I have the 318's  Do the math, if they pulled 500mA each that would be over 70amps! on a light test in a real 737!   

[KyleH]

I concur with Rob.
The Korry's I have (for 767) the bulbs (#387) draw 40mA each x2 in is 80mA (0.08A) per Korry.

I'd measure again and be sure your reading the correct scale.

[Ethanoost]

Thank you everyone for your valuable advice.
I have paid a lot of money for the real Korrys and panels. The last thing I want to do is modify them. I like to keep it as real as it can be.
I will research the extension card Rob talks about connected to my pokeys card.  They are cheap. But I notice they only have 16 ports, not the 80 rob talks about. How does that work?
Regards
Ethan

[Trevor Hale]

I think rob was referring to a maximum number of 80.  5 Cards of 16.

Trev

[KyleH]

I'm not sure what the annunciators for the 737 are like, but I was able to modify my Korry annunciators with a single white LED without modifying any of the exterior of the unit. When it's on you don't notice the difference between the LED and the incandescent bulbs because of the diffuser in them. I'll see if I can dig up some pics.
Now for the Korry switches in my overhead, they use the bulbs as they would be extremely difficult to modify with a 20mA LED and not destroy the switch. So all those are driven with relays.

[727737Nut]

This is the item you need, one pokeys card can drive 10 of them on the poextbus which gives you 80 outputs.    Not that expensive and easy easy easy to interface withh all the sims out there.   

http://www.poscope.com/PoExtBusRE

[Ethanoost]

Thank you Rob.
I'm looking into that
Ethan

[Buster99]

Hello Ethan,

Another option might be to use different lightbulbs instead of hassling with LED conversions.
Instead of the GE387 28 Volt 40mA bulbs you could opt for other bulbs e.g. 6 Volt 1,2Watt (40mA Correction: should be 166mA) bulbs with a MF6s/8 fitting.
In Europe those are sold for roughly 80 Eurocents a piece.
Bulbs are also available in 12 Volt type (and 28 Volt) with a similar Wattage

This solution is something I want to try myself using a 5 volt power supply via regular connection to an interface card. I do not yet know whether operating the 6 Volt bulbs on 5 Volt will yield enough light, I will have to test that first.

Hope this helps.

Best Regards,
Marc

[KyleH]

A 1.2W bulb at 6V is 200mA!

6V at 40mA would be a 240mW bulb.
Please double check all your ratings before trying this. I don't know any microcontroller that can handle that kind of current directly. Even at 5V a 1.2W bulb that is rated for 6V will try and draw 166mA.

Rule of Thumb everyone needs to take away: If it is a 'digital output' do not connect an incandescent bulb directly. Incandescent need a relay or a circuit that will allow higher currents to be driven. 
Digital outputs can drive LED's safely as long as the series resistor is chosen correctly. 

[Buster99]

Hello Kyle,

Thank you kindly for that addition.
I was unaware of that, thought it would be possible. Your remark does make sense, glad I did not set myself up to fry a card!

Best regards,
Marc

[sstusek]

I flew over this topic superficial. Anyway I think I got the idea of the problem, to light up a korry.
This PoExtBus 8 relays board is one possible solutions but as stated above, sort of expensive.

You could try ULN2003A chip (a high voltage and high current Darlington array)? That is what I used for my Airbus Korry`s. With IOcard output sygnal and suitable external power source, 24v or 28v (max 50v), ULN2003A can light up to and 500mA. If your korrys pull 80mA you can connect up to six korrys to one ULN2003A.
You get 100pcs for $10-$15 on ebay, that is less than $0.1 per korry, to light it up, and a lot of soldering

Here is my simlpe diagram for ULN2003 connection. I use OpenCockpits boards! I hope it is more or less understandable.

http://www.ti.com/lit/ds/symlink/uln2003a.pdf

Regards,
Simon

[Ethanoost]

Hi Simon
I like what I'm seeing. I will research that idea. Can I contact you if I need help?
So the card outputs from a pokeys card can be directly connected to the chip inputs. The chip then forms a switch to ground which can handle 0.5A at 28v. Correct?
Thank you for that advice.
Ethan

[KyleH]

That looks like a good idea.
Maybe I'll try that on my next board layout instead of relays.
The one thing I couldn't find in the datasheet is power ratings. I wonder how warm it would get if all the lights on its output are on for a period of time.
I see that the outputs can be paralleled, so you could theoretically get an amp output if needed.

[Danilo]

Of course the outputs (and inputs) of ULN2003A can be paralleled to enlarge current capability.
Furthermore, ground connected to pin 9 will turn on ALL outputs, which can be used for testing of lights without using any software command.

Happy soldering!
Danilo