Smartphone Hack For Adding Magnet Power Dock

Here’s a neat hack for making a magnetic charging mount for a cell phone. We know what you’re thinking, but this is definitely not a traditional contactless charging system. Those use magnets but in a different way. This hack involves putting a couple of magnets onto the case of the cell phone, and a couple more on a charging base. You then wire these magnets into the power inputs of the USB port, and a USB cable onto the base, so putting the phone on the base magnets completes the circuit. The magnets themselves become the charging contacts.

It’s a neat idea, but makes us wonder what this will do to the compass sensor in your phone or your credit cards if they are nearby. With these caveats, it is a neat hack, and could be easily adapted. Want to make a vertical cell phone mount, or a way to attach (and charge) your cell phone to the fridge? This can be easily adapted for that.

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Safely Creating A Li-Ion Pack From Phone Cells

[Glen], at Maker Space Newcastle Upon Tyne, is refreshingly honest. As he puts it, he’s too cheap to buy a proper battery.

He needed a 1AH battery pack to power his quadcopter controller and FPV headset, and since inadequate discharge warnings had led him to damage lithium polymer cells with these devices, he wanted his pack to use lithium-ion cells. His requirements were that the cells be as cheap, lightweight, and small as possible, so to satisfy them he turned to a stack of mobile phone cells. Nokia BL-4U cells could be had for under a pound ($1.46) including delivery, so they certainly satisfied his requirement for cheapness.

It might seem a simple procedure, to put together a battery pack, and in terms of physical wiring it certainly is. But lithium-ion cells are not simply connected together in the way dry cells are, to avoid a significant fire risk they need to have the voltage of each individual cell monitored with a special balanced charger. Thus each cell junction needs to be brought out to another connector to the charger.

[Glen]’s write-up takes the reader through all the requirements of safe lithium-ion pack construction and charging, and is a useful read for any lithium-ion newbies. If nothing else it serves as a useful reminder that mobile phone cells can be surprisingly cheap.

Lithium cells have captured our attention before here at Hackaday. Our recent Hackaday Dictionary piece provides a comprehensive primer, we’ve featured another multi-cell build, and an interesting app note from Maxim for a battery manager chip.

Free Radio On My Phone

If you have owned Android phones, there’s a reasonable chance that as the kind of person who reads Hackaday you will at some time have rooted one of them, and even applied a new community ROM to it. When you booted the phone into its new environment it’s not impossible you would have been surprised to find your phone now sported an FM radio. How had the ROM seemingly delivered a hardware upgrade?

It’s something your cellphone carrier would probably prefer not to talk about, a significant number of phones have the required hardware to receive FM radio, but lack the software to enable it. The carriers would prefer you to pay for their data to stream your entertainment rather than listen to it for free through a broadcaster. If you are someone capable of upgrading a ROM you can fix that, but every other phone owner is left holding a device they own, but seemingly don’t own.

Across North America there is a group campaigning to do something about this situation. Free Radio On My Phone and their Canadian sister organization are lobbying the phone companies and manufacturers to make the FM radio available, and in the USA at least they have scored some successes.

We have covered numerous attempts to use the DMCA to restrict people’s access to the hardware they own, but this story is a little different. There is no question of intellectual property being involved here, it is simply that the carriers would rather their customers didn’t even know that they had bought an FM radio along with their phone. If this bothers you, thanks to Free Radio On My Phone you can now join with others and find a voice on the matter.

It’s interesting to note that many FM radio chips also support a wider bandwidth than the North American and European 88 to 108MHz or thereabouts. In parts of Asia the broadcast band extends significantly lower than this, and the chipset manufacturers make products to support these frequencies. This opens up the interesting possibility that given a suitable app a cellphone could be used to receive other services on these frequencies. Probably more of a bonus for European radio amateurs with their 70MHz allocation than for North American residents.

Via CBC News. Cellphone image: By Rob Brown [Public domain], via Wikimedia Commons.

Upgrading a Nexus 5 eMMC to 64GB

Sometimes we feel confident in our soldering skills (but only sometimes) — and then we see something like this done.

IMG_20160324_205427Someone over on the XDA developers forum managed to upgrade his Nexus 5 from 16gb to 64gb — and not only that, upgraded the eMMC type from 4.5 to 5.0 so it writes and reads much faster.

While the details on the actual conversion are a bit vague, we did manage to dig up another video of someone replacing an eMMC chip from a Samsung Note 2.

It most certainly is possible… but would you look at the size of that chip!

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DIY Thermal Imaging Smartphone

We wish we had [Karri Palovuori] for a professor! As an exciting project to get incoming freshmen stoked on electrical engineering, he designed a DIY thermal-imaging smartphone that they can build themselves. It’s all built to fit into a sleek wooden case that gives the project its name: KAPULA is Finnish for “a block of wood”.

It’s just incredible how far one can push easily-available modules these days. [Karri] mounts a FLIR Lepton thermal camera, an LPC1768 Cortex M3 ARM micro, a GSM phone module, and a whole bunch of other cool stuff on a DIY-friendly two-sided board. The design uses 10 mil (0.25mm) trace and space, which is totally achievable with home etching methods. Copper wire bits fill up the vias. Did we mention he’s making the students do all this themselves? How awesome is that?

[Karri] expects that the students will tweak the software side of things. With additional onboard goodies like an accelerometer, microphone, speaker, SIM card, and USB, it’s not likely that they’ll get bored with the platform. He has a stretch hope that someone will take the hardware and modify it. That’s ambitious for sure, but it’s so cool that someone could.

We’ve seen some sophisticated DIY cellphones before, but this one rises above by being easily DIYable and including awesome extra features. Order parts now, and start etching. You could be sending thermal-photo tweets inside of just a few days.

Build Your Own GSM Base Station For Fun And Profit

Over the last few years, news that police, military, and intelligence organizations use portable cellular phone surveillance devices – colloquially known as the ‘Stingray’ – has gotten out, despite their best efforts to keep a lid on the practice. There are legitimate privacy and legal concerns, but there’s also some fun tech in mobile cell-phone stations.

Off-the-shelf Stingray devices cost somewhere between $16,000 and $125,000, far too rich for a poor hacker’s pocketbook. Of course, what the government can do for $100,000, anyone else can do for five hundred. Here’s how you build your own Stingray using off the shelf hardware.

[Simone] has been playing around with a brand new BladeRF x40, a USB 3.0 software defined radio that operates in full duplex. It costs $420. This, combined with two rubber duck antennas, a Raspberry Pi 3, and a USB power bank is all the hardware you need. Software is a little trickier, but [Simone] has all the instructions.

Of course, if you want to look at the less legitimate applications of this hardware, [Simone]’s build is only good at receiving/tapping/intercepting unencrypted GSM signals. It’s great if you want to set up a few base stations at Burning Man and hand out SIM cards like ecstasy, but GSM has encryption. You won’t be able to decrypt every GSM signal this system can see without a little bit of work.

Luckily, GSM is horribly, horribly broken. At CCCamp in 2007, [Steve Schear] and [David Hulton] started building a rainbow table of the A5 cyphers that is used on a GSM network between the handset and tower. GSM cracking is open source, and there are flaws in GPRS, the method GSM networks use to relay data transmissions to handsets. In case you haven’t noticed, GSM is completely broken.

Thanks [Justin] for the tip.

Smartphone and IR Line Laser Measure Distance

Measuring the distance using lasers is a mainstay of self-driving vehicles and ambitious robotics projects. The fine folks at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) decided to tackle the problem in an innovative way. [Jason H. Gao] and [Li-Shiuan Peh] used an infra-red (IR) line laser and the camera on a smartphone. Their prototype cost only $49 since they used a smartphone that was on hand. The article reports good results using the device outdoors in direct sunlight which is often a challenge for inexpensive lidars.

The line laser creates a horizontal line that is reflected back to the camera on the phone. The vertical position of the laser on the camera image lets the phone calculate the distance by parallax. To bring out a faint laser reflection, the algorithm compares four images – two with the laser on and two with it off – and subtracts the background. Using a smartphone for this is ideal since it automatically adjusts for light level and can easily be upgraded to a newer phone with a better camera later.

This should be a cheap and easily replicable setup. If you make one of these, let us know. If you need something more refined, check out this post on interfacing the Neato vacuum cleaner’s XV-11a lidar with the Raspberry Pi.

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