MGL Avionics User Forum

Wanting to wire a input to my ibox for flipping the com 1 freq. Considering the button in the stick is ran off a ground. How would I wire this? Just want to make sure it is right. Also am I able to use the ibox power output vs for powering the uma tach sensor along with the rdac an sp-9 ?

Yes you can use the power from the iBOX output. Please en sure that that goes via a fuse (2A). Any overload here can damage the iBOX if you do not have a fuse in line.

Apply 12V from any source to your desired iBOX analog input via a momentary closure contact then assign your desired function in the Digital inputs setup menu (also make sure you select "active high" so it switches when you make the contact).

rainier wrote: ↑Mon Oct 19, 2020 7:52 am Yes you can use the power from the iBOX output. Please en sure that that goes via a fuse (2A). Any overload here can damage the iBOX if you do not have a fuse in line.

Apply 12V from any source to your desired iBOX analog input via a momentary closure contact then assign your desired function in the Digital inputs setup menu (also make sure you select "active high" so it switches when you make the contact).

So how would this work with my button switches being ran off a ground. Would I have to wire a relay to convert to the 12v, then feed the 12v off relay to the ibox?
Sorry I work well with wire diagrams

Many ways to kill a cat...

The easiest is a switch to 12V as the iBOX effectively contains a pull down resistor (as part of a voltage divider) on its input.

However what you can do very easily is connect say a 4K7 resistor (Value not hugely critical - anything from 2K2 to 10K should work) from the iBOX input to 12V. Your switch would go from that input to ground. All you now need to do is select the input as "active low" in the setup.

The resistor will keep the input at around 10V or so (depending on what value you end up with) and when you close the switch it goes to zero.

So it would be like this. And I would just pull the 12v off the input power for ibox ?


https://photos.app.goo.gl/K4d26KQsYzfX5SME9

Yes

Got it thanks appreciate the help

rainier wrote: ↑Mon Oct 19, 2020 2:49 pm However what you can do very easily is connect say a 4K7 resistor (Value not hugely critical - anything from 2K2 to 10K should work) from the iBOX input to 12V. Your switch would go from that input to ground. All you now need to do is select the input as "active low" in the setup.

The resistor will keep the input at around 10V or so (depending on what value you end up with) and when you close the switch it goes to zero.

I am using a Flight Data Systems GD-40 CO detector The "RLY" terminal on the GD-40 is provided for driving an EFIS. However, the manual specifically says not to connect this terminal to 12-28V. With the resistor, the terminal gets 10V but I am afraid that will still be too much. How can I proceed in this situation?

Loman wrote: ↑Fri Jan 08, 2021 4:55 pm

rainier wrote: ↑Mon Oct 19, 2020 2:49 pm However what you can do very easily is connect say a 4K7 resistor (Value not hugely critical - anything from 2K2 to 10K should work) from the iBOX input to 12V. Your switch would go from that input to ground. All you now need to do is select the input as "active low" in the setup.

The resistor will keep the input at around 10V or so (depending on what value you end up with) and when you close the switch it goes to zero.

I am using a Flight Data Systems GD-40 CO detector The "RLY" terminal on the GD-40 is provided for driving an EFIS. However, the manual specifically says not to connect this terminal to 12-28V. With the resistor, the terminal gets 10V but I am afraid that will still be too much. How can I proceed in this situation?

It's a switch to ground (using a relay). It does not have any practical voltage limits in this case - what the manual wants to say is "don't connect this directly to 12-28V" - as obviously if the relay switches on in this case it will try and short your supply to ground. Things will go "poof !".
In your case there is a resistor in series with the switch that limits the current to next to nothing and there is no issue.

Just checking over my work (over a year later ) and I find I need to clarify just one thing from this old post:

I followed the hand drawn diagram linked by Matt above. Rainier also says "Your switch would go from that input to ground. All you now need to do is select the input as "active low" in the setup".

Both of these suggest strongly that the corresponding G pin for that input is ignored but that makes me uneasy because an amateur like me would think that the two pins ("A1" and "G" ) together form that 'input' and the iBox is sensing the voltage across the pair.

Can I be reassured that both input and switch-to-ground output are wired to the same Input pin and the corresponding G pin is ignored?

It would great to know for sure before I get to the point of pushing buttons to see if it works.