Ask HN: Interesting things to do with old smartphones?

I usually keep my previous phone whenever I get a new one so I have a backup in case I break/lose my main one and it takes a little while to get a replacement.

Other than that, I was going to use an old iPhone or Android phone as a wall-mounted touch panel for my Hue lights or to run media apps to cast to one or more Chromecasts around the house. The original plan was to put the phone in a 3-gang box in the wall with some foam or other material to hold it in place. Then I attempted to use my dremel to rout out an opening in a blank plastic wall plate so the phone was held in place but the screen was accessible.

Unfortunately my dremel skills aren't good enough to the point where I could get one looking good enough that I'd want it on the wall. I guess I should just have one 3d printed but I've slept on it after the initial disappointment.

Additionally, I wouldn't be able to mount the power supply in the wall if I want it to be safe/up to code so I would need to run the wire down behind the wall and have it exit out of a notch in the receptacle wall plate below it near the floor with the wall wart plugged in. Still not very attractive so there are definitely shortcomings with this concept.

In the end, it's just been easier to use our existing phones since they're always close at hand and my ambition comes and goes with projects like this. It's a real shame that there don't seem to be any ready-to-buy, relatively universal wall mounts for charging and using smartphones or tablets this way. I've seen some but they're usually specific to one model of phone or tablet and they tend to be pretty expensive and ugly.

Install BotBrew and use it as FTP/Web/File Server.

Use it as a Chromecast controller.

Maybe build a cool robo/drone/tool using Arduino and use your phone to control it.

Maybe, as a paperweight too? Even a non-functional phone would work here! :D

You can also use it to build a telepresence robot leveraging the android os. Here is the one my friends and I built for a tech event. http://akhilspassion.blogspot.co.id/2014/10/worlds-cheapest-... Let me know if you want the code / design.

With something like this: https://www.adafruit.com/product/2264

You can easily connect a lot of things to your mobile and automate them. The phone already has a lot of sensors so I would think more along the line of "which motors can I connect my phone to?". You could build a robot for example...

If we could flash some educational stuff on them and pass them to some poor children to learn from (and monitor their scores) - it would make a cool project. I would like to work on this next year (hopefully).

This 'Show HN' decided to make old smartphones into an inexpensive car/fleet tracking solution:

[1] https://news.ycombinator.com/item?id=12240542

[2] http://gping.io/

Use for home improvement. Can hang in the wall to show current weather, motivational quotes, old photos etc in a beautiful UI.

dedicated google cardboard viewer!

Security cameras.

Work on adding support to Linux mainline for them, so people can eventually run distros other than Android.

You can install an app like Torque and use it with a car dongle for monitor your car

use it as a music player device in your car maybe ? Most smartphones work well past their intended usage time. Its better to repurpose it for specific uses like playing music or for maps.

Trap shooting.

(I know, it's probably bad for the environment...)