737 overhead panel interface problem

[Jahanzeb]

That's it exactly. Now grab yourself a few hundred of the IN4001 on ebay and you're all set. Watch the polarity though of the diodes : the little stripe in the diode symbol is the white stripe on the diode itself.

The diodes didn't work. I watched out for polarity. It worked partly. I used 3 diodes on the keys kcd as they cannot pre pressed together. Surprising it worked. But after switching it off and on about 5 to 6 times it stopped working. I spent hours trying to figure it out. But I couldn't. Even made the whole matrix on a piece of paper and and schematic diagram. So I've gone back to working with relays.
So I ordered about 20 6v relays. 5pin. Along with 1000um capacitors. Ran into anther problem. I understand that capacitors have polarity too. So I connected the circuit. Positive 6v external supply connected to the shorter leg of the capacitor and the electromagnetic switch connected to the keyboard. The switch works fine. The Problem is, it stays on. Doesn't close. Sometimes it does, sometimes it doesn't. And to top it off, one switch is working perfectly. I have the Same connection for the second and third switch, but they stay on. If I decrease the voltage, the switch doesn't flip at all.
Im guessing I'm using a wrong capacitor or something. Can someone help me with this? My frustration has peaked.

[Jahanzeb]

Hi.

On a total different note, I am also building my own overhead. So I have drawn all overhead-panels in an illustrator-file, ready to print.
So if you like you can print the file (or parts of it). I printed it on white sticker and so I wrapped each panel around a piece of plexiglas/Foamalux.
Is a cheap way of making your own owerhead that looks - somewhat - like the real thing.
If you want to give it a go you can see how I have done on my blog (See the signature)

EDIT: So I can't upload the Illustrator .ai-file to the site. But an older pdf-version is on the blog.

that is a brilliant idea. I read it somewhere else too but the author said he printed two stickers. One normal and one inverted on a sticky paper. So I dropped the idea because I didn't understand why he needed an inverted one. I eventually do want to install panel lights. So wont the whole sticker become translucent? How can I light up specific area of the overhead panel? For example the white lines connecting the cross feed and fuel pumps?
How easy is it to drill holes in plexiglass? Doesn't it crack or something?

checked your blog. Looks absolutely stunning. Hard to believe its a printout. Il be following it more closely. What IO cards are you using? Are the guages functional? You need a servo for that right?

[Jahanzeb]

for anyone reading this, and having similar problems, the capacitors and relays worked. i ran into quite a few problems, but eventually everything pulled together. i now have working momentary toggle switches for the overhead panel connected to a a keyboard PCB. il try to upload the schematics if anyones interested.