I'm a real nu-bee at this but I thought I would post it here. I have a nu-tone intercom system in my house that I do not use and would like to use the wiring system to wall mount a fire 7 tablet to the wall. What and how, step downs, would I need to wire it to the tablet. I have a C7 Hubitat hub. Also what software is popular other than dashboard to configure the tablet. I'm not an electrician so would need basic instructions on wiring this project. If this is not the appropriate forum please advise if another forum would better fit my situation.
It might be possible to use the existing wiring for power.
What's the model number of your intercom system?
As for what to run on the tablet, I'm partial to this community app:
Something like this should get you 5VDC from your 16VAC supply.
Converter and test/adjust.
Add a connector.
I highly recommend Hubivue.. I've been beta testing for a few weeks now, and it s really a strong contender, with a developer focused on its success. Very responsive and open to feedback .
Thank you so much for the recommendations. As mentioned I'm not an electrician so was wondering if you could help on wiring the converter. I have submitted a photo of the wiring of the back of one of the intercoms,
Thank you so much for the recommendation, where would I go to obtain this software and is it available for IOS and android?
Google is your friend, yes on IOS and Android.
Hmm, how many tablets were you hoping to install?
You might run into issues with the amount of power you need for multiple tablets.
Can you take some pics of the wires coming in/out of the boxes please.
I'm looking to do two tablets. I'm not sure what you mean out of the box, I submitted a picture of the wiring to the intercom. I have submitted a picture of the wiring of the amplifier and the boxes attached to it.
Let me know what additional information you need.
More pictures. 
You have 2 x AC transformers feeding into that clump of wires so first question is: Why?
Is there a doorbell integrated into the system?
You can try disconnecting the right (as you're facing it) transformer and see what quits working. 
By "box" I meant electrical junction box. But it looks like the wires are just coming out of a hole in the wall?
If you're planning on removing the intercom anyway, might as well do it now and take some more pics of what's left.
And lastly, I'd check what's going on with these wires.
Not to mention the metal cover on metal box strain relief technique. 
