PeriUSBoost: A DIY USB Battery Pack

If you travel often, use your mobile devices a lot, or run questionable ROMs on your phone, you likely have an external USB battery pack. These handy devices let you give a phone, tablet, or USB powered air humidifier (yes, those exist) some extra juice.

[Pedro]’s PeriUSBoost is a DIY phone charging solution. It’s a switching regulator that can boost battery voltages up to the 5 volt USB standard. This is accomplished using the LTC3426, a DC/DC converter with a built in switching element. The IC is a tiny SOT-23 package, and requires a few external passives work.

One interesting detail of USB charging is the resistor configuration on the USB data lines. These tell the device how much current can be drawn from the charger. For this device, the resistors are chosen to set the charge current to 0.5 A.

While a 0.5 A charge current isn’t exactly fast, it does allow for charging off AA batteries. [Pedro]’s testing resulted in a fully charged phone off of two AA batteries, but they did get a bit toasty while powering the device. It might not be the best device to stick in your pocket, but it gets the job done.

Using the Wrong Screw: A Painful Lesson in iPhone Repair

If you’ve ever had to repair an iPhone for a friend, you’ll know they have a ridiculous number of screws. Most companies standardize screws in their products, but since Apple doesn’t expect you to fix a phone yourself… they may have let this one slide.

You see, each of these screws is different.iPhone screws The red ones are 1.7mm long, the yellow one, 1.3mm, and the orange one, 1.2mm.

Guess what happens if you install either red or yellow screws into the orange spot, since your eyesight isn’t good enough to notice a 0.1mm difference? The screw will cut into the PCB and break several 50 micron traces, as shown in the picture above, causing a blue screen error on the phone.

Fun stuff.

[Sam Schmidt] is the owner of a repair outfit called iRepairNational, and he and his team spent a day trying to figure out the problem – it’s not exactly easy to spot. They’ve managed to repair it by cutting thin strips  of copper foil (the width of a human hair) and floating it into place using the surface tension of the flux they were using for soldering. On average it takes them around 2 hours to do the repair, though they’ve done a few in just under an hour.

Since discovering and sharing the problem, they’ve had customers around the world sending in phones for repair – often at the fault of someone else trying to repair something completely different in the phone, and then using the wrong screw as they put it all back together.

Estimating BB Gun Muzzle Velocity with a Voice Recorder and a Curtain


[Luke Wren] just wrote in to tell us about his new science blog called Wren’s Tech — it’s only a few days old, but he’s already got some pretty cool science experiments written up! Like how to estimate the muzzle velocity of a BB gun using just a voice recorder, and a curtain!

There are many different ways you could do this. One of the easiest is using a high-speed camera with a known grid or pattern as the background — like how Mythbusters does it. Unfortunately, high-speed cameras are usually out of reach for most hobbyists. [Luke] explains a rather cool system you can build with some electronics, whereby you have two thin wires a known distance apart — run current through both and use a circuit that can detect the interrupt as your projectile breaks the wires — or, you can use a voice recorder. Continue reading “Estimating BB Gun Muzzle Velocity with a Voice Recorder and a Curtain”

Pwning Timberman with Electronically Simulated Touchscreen Presses


What do you do if you suck at a smartphone game? Buy some in-game upgrades to pretend like you’re good? Screw that! [Valentin] did what any self-respecting hacker would: developed an automated system to play for him.

Granted, when you see the demo video embedded below you’ll realize there isn’t much strategy involved in this game. But that setup to simulate the touchscreen presses is pretty neat. We’re used to seeing mechanical touchscreen hacks but this one is electronic, using a couple of pads of copper foil tape and some relays to make it happen. Here’s the one caveat: you still need to be touching something with your hand. This just uses the relays to switch the connection between the pads and your body.

We’ve looked around for this before. Does anyone have a cheap, simple, and effective hack to fully automate presses on a modern touchscreen? Can we use a potato or something? Tell us below, but send it in to the tips line too!

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Embedding Wireless Charging into Your Laptop

Wireless charger in chromebook

Looking for a project to do [Jason Clark] thought it might be fun to integrate a spare wireless Qi charger into his HP Chromebook 14.

He started by cracking open the Qi charger — it’s held together by adhesive and four phillips screws hiding under the feet pads — all in all, not that difficult to do. Once the plastic is off, the circuit and coil are actually quite small making it an ideal choice for hacking into various things. We’ve seen them stuffed into Nook’s, a heart, salvaged for a phone hack…

Anyway, the next step was opening up the Chromebook. The Qi charger requires 5V at 2A to work, which luckily, is the USB 3.0 spec — of which he has two ports in the Chromebook. He identified the 5V supply on the board and soldered in the wires directly —  Let there be power!

While the coil and board are fairly small, there’s not that much space underneath the Chromebook’s skin, so [Jason] lengthened the coil wires and located it separately, just below the keyboard. He closed everything up, crossed his fingers and turned the power on. Success!

It’d be cool to do something similar with an RFID reader — then you could have your laptop locked unless you have your RFID ring with you!

The Rotary Cell Phone


It’s happened. It’s finally happened. In a move that has hipsters donning their good flannel and breaking out that case of Genesee they were saving for a special occasion, the rotary cell phone is now a reality.

[Jaromir] created this astonishingly retro future device as an entry for the NXP LPC810 challenge, a contest to do the most with an ARM Cortex M0+ microcontroller in an 8-pin package. Having only six I/O pins for controlling a GSM module, display a few buttons, and the fancy rotary dial meant [Jaromir] needed to expand his I/O some way. He chose a shift register to handle the buttons and display in a somewhat impressive demonstration of using a shift register as both an input and output expander at the same time.

From the videos [Jaromir] uploaded, the rotary cell phone isn’t ready for Think Geek to do a production run quite yet. He needs to enter the PIN for the SIM card, AT commands for the GSM module, and is, of course, a horrible method of user input for the younglings who have only seen rotary phones in old movies. That being said, it’s a rotary cell phone running on an 8-pin microcontroller. What more do you want?

Videos of this awesome this truly awesome phone in action below. If you’d like to build your own – and why wouldn’t you – all the files are available on [Jaromir]’s git

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Call A Cell Phone, Find A Tent

relay Finding your tent at a music festival is a tricky endeavor – not only are there miles and miles of tents exactly like yours, you most likely have a few beers or other substances in you that affect your sense of space and/or time.  [James] came up with a great solution to finding your tent by illuminating it with Christmas lights and a cell phone.

The basic idea of [James]’ build is having Christmas light flicker whenever he calls a phone. One feature in nearly every phone that can be exploited to accomplish this task is the backlight turning on when a call is received. Add a phototransistor, a little bit of circuitry, and some Christmas lights, and you have a fully functioning tent finder.

[James]’ circuit is a simple relay driving the Christmas lights, triggered by a phone right on top of the phototransistor. It’s a simple circuit that can be built on a piece of veroboard, and with a few pieces of plastic forming the enclosure, provides a reasonably bulletproof device that will survive the rigors of a music festival. As a bonus, there’s no need to modify the phone to trigger a remote circuit. Video of the device in action below.

Continue reading “Call A Cell Phone, Find A Tent”