Smartphones don't just replace your camera and MP3 player – they can do things that you would never have done before, from flying a drone to reporting earthquakes.
Free on Android
Did you know you had a motion-activated CCTV security camera and alarm in your pocket? Your smartphone or tablet already has everything needed to build one, all it needs is the software to make it work. Salient-Eye does exactly that, using the device's camera as a motion detector, the screen as a viewfinder, the speaker as an alarm, and its wireless connectivity to upload photos and send alerts via SMS or email.
Set-up is simple, if a little oblique. All you need to do is install the app, set up a PIN for disarming the alarm, and add the destination addresses for email and SMS alerts if you want to use them. You then activate the app, position the camera so it can see the area you want it to cover, and leave it to arm itself a few seconds later. Positioning it just right may take a little practice, for example if you have pets roaming around you may need to angle the camera a little higher to avoid false alarms.
When it detects movement within the camera's field of view, the app takes a photo roughly every second, and if the alarm is enabled it sounds an alert too. The photos are stored on the phone and also uploaded to a Web service – you get a message telling you where to find them. The developers say your photos are stored online for at most a month, and they can be deleted earlier if requested.
There are caveats – you cannot adjust the activation range, and you will get false alarms. We found it activating when a lamp on a time-switch turned off, for example. It is best if the device is on charge too, to avoid running the battery flat. But it really does work, activating on movement and uploading the resulting photos, so if you have a spare Android device or want to protect yourself overnight, this could be a good route to take.
Free on Android, iPhone, Windows Phone
Most modern smartphones and tablets are equipped with all sorts of sensors, including accelerometers to detect inclination and movement. As well as switching the screen from portrait to landscape, these help with gaming and navigation, but smart programmers have put them to a bunch of other uses too, including turning the device into a vibration meter or seismograph.
For a basic yet very competent version, try iSeismometer. It uses those accelerometers to create the classic pens-twitching-over-moving-paper look, familiar from those earthquake horror films. Tap the table or move the phone – or experience an earth tremor – and the pens reflect that.
If you have an Android device and fancy something rather more sophisticated, check out Earthquake Network. You don't get the twitching pens, but when your device is charging and has its screen off this free app joins a worldwide network of location-enabled seismometers, reporting tremors that your phone senses.
The app also lets you view where others – both smartphone users and major seismological survey organisations – have reported quakes, and can optionally send you quake-alerts too. The startling aspect of this is just how many there are, but most are in remote areas or at sea, so they go largely unnoticed.
Written by an Italian statistician, Earthquake Network is also a research project and a learning tool. You can layer the tectonic plates and geological fault lines on the map, view where the risk of an earthquake is highest, and if you register as a user – registration is not essential to use the app – you can enter a monthly competition to predict where the next big earthquake will strike.
Free to £1.49 on Android, iPhone, Windows Phone
Accelerometers can equally well be used to turn the device into a spirit level or clinometer. There are apps on pretty much every mobile platform to graphically simulate a spirit level – indeed, if you are an iPhone user, it is now a standard feature of iOS7. You will find it on the second page of the iPhone's built-in Compass app; it can work horizontally or vertically, and usefully the display goes green when the surface is level.
There are still plenty of alternative apps though, and one of the most clever of them takes it a stage further. Simply called Clinometer, it starts out as a two-dimensional bubble level, useful for checking an edge or surface, but once you lift it past about 40 degrees it switches to become a clinometer, so you can measure angles of slope or tilt.
The versions of Clinometer for different platforms do vary a bit. For example, the Android and iPhone apps include a 1V:H unit mode for engineers, and the Android app has a rooftop mode too. There is also a camera mode – included as standard in the £1.49 iPhone app, or as a 69p add-on for the Android app – which lets you measure angles via the phone camera. You can then use this plus some trigonometry to calculate the height of a building, say. Another feature standard in the iPhone app but extra on Android allows you to measure relative angles to determine, for example, the angle at which two beams or surfaces meet.