# Thread: OpenCockpits: Use of common ground for more than 9 inputs by split...?

1. ## OpenCockpits: Use of common ground for more than 9 inputs by split...?

Hi everybody,

does anybody know, if it is possible with OpenCockpits to use a setting in which you have more than 9 inputs connected to the same ground ?
It does not work by splitting the ground to two and connecting the two wires to two grounds on one inputs card and also it does not work to connect the two "split" grounds to two diferent entries one one Master card.
So I was wondering if it might be possible to either use a trick to fool the master card or to connect it to two different master crads (but I don't know if that might create a short circuit that might harm the cards).
The reason why I need to know is that I would like to use my real transponder but the numbers are encoded by 3 inputs each so that alone will use 12 inputs.

Any ideas are highly appreciated.
Regards,
Florian

2. ## Re: OpenCockpits: Use of common ground for more than 9 inputs by split...?

No you cannot have more then 9 inputs share the same ground, but that should not be a problem:

I understand that you have 4 digits each with 3 inputs so 12 inputs total. Why do you want these 12 inputs to share a common ground? There is no need to...

Solution:
Put 9 inputs (for three digits) in one group of 9 inputs; let these 9 inputs share a common gnd connected to the gnd of that group. Put the other three inputs (of the 4th digit) in another group of 9 inputs; let these 3 inputs share a common gnd connected to the gnd of that group.

Note that these two groups of 9 inputs do not have be at the same Mastercard (but they may of course)
regards,
Nico Kaan.

3. ## Re: OpenCockpits: Use of common ground for more than 9 inputs by split...?

Presumably the device currently has 12 inputs and one common lead. Can you find a way to add a separate common for one group of 3?

4. ## Re: OpenCockpits: Use of common ground for more than 9 inputs by split...?

Originally Posted by deering
Presumably the device currently has 12 inputs and one common lead. Can you find a way to add a separate common for one group of 3?
Then I have to see the device.... But I guess that should be possible. If you can see the common lead, just cut the wire after the 9th input. Or if a pcb is used, detach the three ground pins (for the last three inputs) from the pcb and solder a common wire to these three ground pins...
Nico

5. ## Re: OpenCockpits: Use of common ground for more than 9 inputs by split...?

My question was for Florian.

6. ## Re: OpenCockpits: Use of common ground for more than 9 inputs by split...?

Thanks for the replies.
The transponder is a Gables G-4484, I am afraid that the inputs are all connected (grounded ?) to the case of the transponder, so they are all interconnected and it would probably be hard to find a way out to separate them from each other (sorry for abusing the term "ground", lead might have been more appropriate). Nevertheless, I will try to find if there is a way to separate them, perhaps, as you suggested, to cut a wire and solder a new wire to it to form a second ground.
I had only hoped that there might be a way the fool the cards and to use the original wiring.
I will keep you posted on the rpogress and if anyone has another hint...
Regards,
Florian