Interfacing real 727 eng gauges

[Mike.Powell]

Here's the complete schematic for the tachometer adapter. The conversion process happens inside the PIC. The 555 chip is used as a voltage inverter to make a nominal -5 volts (actually closer to -4) so the final tachometer signal swings below as well as above 0 volt.



Rob's working on a circuit board. Once he pulls that together, we should see some nice pix of a working A/C tach under the control of an OpenCockpits servo card.

[Mike.Powell]

Rob and I have been bouncing printed circuit board layout ideas back and forth. Here's where we are now. This is a triple RC servo control pulse to real A/C tachometer adapter. I don't think we'll build this particular version. Converting one of the adapters to an EGT adapter might be more useful.

[737NUT]

This has been a very fun and educational project for me and can not say enough thanks to Mike for all his help!!! I am looking forward to the next challenge in my quest to use as much real stuff as possible. To me, this has become almost more fun then flying, almost! This is my first time using PCB software and PIC controllers and my next goal is learning to program the PIC's. I plan on using Mike's synchro driver pcb project as well to drive the EPR gauges. Whats neat about this project is that we proved that the gauges could be driven by 2 different methods and actually 3 if eliminated the servo card interface. Fun stuff!!

[RadarBob]

Nice work Guys - Knew you would get there in the end!

Cheers,

Rob

[Melnato]

Mike/Rob...I am REALLY intrugued by the work you have done with these gauges...I just wish I understood what you were doing

Is any real gauge "interfaceable"? I'd love to do an RMI, Artificial Horizon and Altimeter (737 style what else)...
Are the above 3 gauges easy/hard/impossible?????

Any feedback appreciated.

Cheers,

Nat

[737NUT]

Mike/Rob...I am REALLY intrugued by the work you have done with these gauges...I just wish I understood what you were doing

Is any real gauge "interfaceable"? I'd love to do an RMI, Artificial Horizon and Altimeter (737 style what else)...
Are the above 3 gauges easy/hard/impossible?????

Any feedback appreciated.

Cheers,

Nat

Absolutely! I just did a real 737 VSI, it was easy! See my post. An altimeter is next then the RMI and ADI. Look for more updates. With SIOC and OC cards and Mike's books, ideas and help it's all possible. Im no engineer, just a hobbiest electronics guy.

[Melnato]

Thanks Rob!

Keep us posted on the altimeter and RMI...

I have NO..ZERO... SIOC experience...should I bother?

Nat

[737NUT]

Thanks Rob!

Keep us posted on the altimeter and RMI...

I have NO..ZERO... SIOC experience...should I bother?

Nat

There are enough examples and code out there for anybody to learn and get started in. I self taught myself by looking at other codes and expierementing with codes of my own. Not overly difficult, just takes us non-programmers longer to do.

[737NUT]

Just a quick update on the project status. I placed an order for all the electrical components so as soon as they arrive i will assemble a test set-up and hook to sim. Will report back soon!

[737NUT]

SUCCESS!!!!!!!!!
Got all the parts in today so breadboarded up a temp cicuit with the PIC from Mike and hooked to my OC servo card. Firgured out the slope and intercept angles,quick program in SIOC and PRESTO! The real gauge matched the sim perfectly!! YEA! So cool seeing the needle and digital read-out working with the sim. Amazing what you can do with such a small IC chip. and a few cheap components! Thanks to Mike Powell and David Allen for all the help. Will post a video once i find a loaner camera.