737-200 overhead build

[ElStino737]

Hello everyone,

I'm Stijn from Belgium. I'm 35 years old. I've been flight simming for a number of years and used to have a crude and simple 737-800 home cockpit a number of years ago. I stopped around the time FSX came out, but always kept one eye on the hobby. Recent developments with arduino's and Teensy's interfacing with real Boeing analog hardware (mostly by Rob Archer) really caught my imagination.
When I recently saw an almost complete 737classic overhead on ebay for a really good price I could 't resist.

I will be building this as a separate project, not a full cockpit at this time. I will be moving house in about a year and I will have a lot more room there. I plan on using Xplane10, FlyJsim 737-200 and Teensy for interface. I'm hoping certain people will jump in here with advice and answers, because i'm sure I'll have plenty of questions along the way.

I'm doing the forward overhead first. I took all the modules out and i'm doing the T first. (It's from 734 I believe, but It came with lots of -200 modules.
Tested the backlighting and it looks great! How are you other builders doing the dimming?
Any way of using the original rheostat? That's 28V AC 400Hz in and 0-28VDC out.

Some pictures for now:

[ElStino737]

Could I use something like this with the original backlighting rheostat?

[Trevor Hale]

Welcome to the group.  If you are going to be using the Teensey anyway, I would setup a PWM channel Output and adjust the PWM Range with a POT. That way your not messing with anything else.

Trev 

[ElStino737]

Ok, that would be simpler. I would also be able to turn them off if power is taken off the busses, so I like the idea.
But what would the PWM signal drive? some kind of transformer?

[Trevor Hale]

Well if it is a 5v output to the lights, depending on the current, you can have the teensey drive them directly.  (Honestly this works waaaay better with LED's) But no reason it wouldn't work for the bulbs just wire them through a BIG THICK Transistor with good heat dissipation.

[ElStino737]

I think the backlighting for the complete overhead will be over 10 amps. The T alone is 2,4 Amps.

[jackpilot]

I Have the FDS front and aft OVH (using lamps for Bklght) and it is fed with heavy  12G wiring from a 1000W PC power supply.
Jack

[ElStino737]

I Have the FDS front and aft OVH (using lamps for Bklght) and it is fed with heavy  12G wiring from a 1000W PC power supply.
Jack

How do you dim it?

[Goodenough]

I'm new to sim building as well and learning lots here from other sim builders on CB. I like your overhead. Nothing like having the real thing. A while back I bought a DC-9-30 cockpit section and restored it to original state. Then sold it to Petr at www.dc-9.eu/
Check it out. I;m sure if you contacted him he could offer some direction in this regard
Perry

[jackpilot]

How do you dim it?

I don't , No real point in my opinion, Perfect intensity at night, off in daylight.
One less source of issues.
I have these but never managed to use it.
http://www.flightdecksolutions.com/components/hardware/

[ElStino737]

I really want full functionality on the dim switch. The more I look into this , the more I think the real aircraft transformer is the way to go. I could power it with an of the shelf 28VDC power supply (wich I need anyway for the Korry's). I could control the transformers output with a 0-5V PWM signal to the transformers control pin from the teensy or a cheap 0-5V Chinese dimmer. The problem is the Amps. Most people seem to use LED's these days, witch draw a lot less amps. The OEM light plates (and all the gauges) together draw a lot of amps. i can't seem to find an off the shelf solution that can dim 0-5Volts and let's say 15A.

[mickc]

I built my dimmers using arduinos and Mosfet Shields, they can run 6 independent channels up 30v @ 20 amps

[ElStino737]

I built my dimmers using arduinos and Mosfet Shields, they can run 6 independent channels up 30v @ 20 amps

I think you just solved my problem! I have to look into it some more, but this looks promising.
Would you be willing to share the sketch for that, so I can understand it better? The programming side is my weak point here.

[kurt-olsson]

Yeah, mosfets are the way to go for backlighting. Can take alot of heat and current. Check this out:
https://youtu.be/sVyi7yWuXxs

[kurt-olsson]

Let me know if you have troubles with teensy interfacing the panels, i have the same OEM panels. 

[ElStino737]

You guy's are using an extra component with the Teensy to make it handle the Korry's. Can you point me in the right direction for that?

[kurt-olsson]

I use a uln2803a driver. That is what i use for my korrys. Paralell the pins and you can drive 2amps through one chip.

Use analog output on teensy.

[mickc]

I think you just solved my problem! I have to look into it some more, but this looks promising.
Would you be willing to share the sketch for that, so I can understand it better? The programming side is my weak point here.

Sketch is attached, this is a simplified version of the ones I run.

This handles the 12v LED panel backlighting, 5v OEM gauge lighting, 12v floodlighting for panels and AFDS and the 3.3v LED backlight for the MFD buttons.
One pot controls all the panel lights except for the flood lights which have their own pots.

My full sketch incorporates 2 channels for the panel lighting and some switching for the emergency panel lighting, but I have omitted it from this example.
The emergency panel lighting is simulated as per the real aircraft, where only some of the MIP panels will light up at a fixed brightness when no AC power is available.
Once AC power is available, the rest of the panels come on, and can be dimmed by the dimmer as normal.  Emergency panel lighting will also turn off if the standby power is turned off manually.

I use a Freetronics N-Drive shield to do the dimming, http://www.freetronics.com.au/collections/shields/products/n-drive-shield#.WHYAE1V96Uk

[ElStino737]

Thank you some much for everyones input already. I will surely be making progress now.
Currently extending the cut wire loom on the overhead T so I can connect it up to the Teensy. Lot's of soldering. It's going to take a while. 

[ElStino737]

I finished the wiring loom on the T. I ended up redoing the whole thing, made more sense to me that way.

I ordered some more teensy's, mosfet and relais card for the backlighting and the starter switches.
My overhead came without starter switches so I ordered these from Archen Simparts, these seem very realistic.

Waiting for orders and nothing much to do the main panel for now I turned to the generator module.
I figured out how the APU EGT gauge works. It +/- takes a 0-25mV signal.
Can anybody point me in the right direction to how do this with the Teensy? I could make a servo operate a potentiometer, but is there a way to create the signal directly from the Teensy?

Anybody knows what makes these AC amp gauges tick? I haven't tried anything yet, but want to ask here before I fry something. Haven't been able to find much info on these. Surely someone here knows.

[ElStino737]

Anybody know a good source for the 5V incandescent lightbulbs. I have several light plates with broken bulbs I need to fix.

[Trevor Hale]

Anybody know a good source for the 5V incandescent lightbulbs. I have several light plates with broken bulbs I need to fix.

Just wait until you see the price of them lol

[ElStino737]

Ha, yea I found the part number for the bulbs on the back of a lightplate. MS90451-6832.
Could be worse I guess. Looks like they are 80Eurocent each.
None of this stuff is cheap if you have to get it new...

[Ridgenj]

I got Chicago Miniature bulbs from online components.com. I am not sure but I thinks I paid  78 USD for 100.
Have good experience with this vendor


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[B747-400]

Hi Stijn,

I'm in the same boat like you ... I need bulbs for my B747-400 panels. I found another source:

http://www.alliedelec.com/wamco-inc-wl-6832as15/70117647/

More or less same pricing!

Does anybody has experience with this shop?

Cheers
Hans