TechCrunch Disrupt: Charging A Phone With Its Own Transmitter

TechCrunch Disrupt is on this week, and that means we get to see which members of tech media don’t understand basic physics. So far, it’s writers from Engadget, The Mirror, Business Insider, TechCrunch, and four judges on the TC Disrupt stage. What is the consequence of not understanding the implications of the conservation of energy? Glowing support for a cell phone that can charge itself.

The offending Disrupt startup is Nikola Labs, and they’re gearing up to launch a Kickstarter for a very special iPhone 6 case. This case uses small, energy-harvesting antennas to gather RF energy from the cellphone tucked away in this case. This energy is then sent to a rectifier where it is converted into something the Apple Lightning connector can sip power from. According to Nikola Labs, this RF harvesting antenna takes energy from the transmissions of the iPhone 6 entombed in this case, converts it to about 5 Volts, and uses that to charge the iPhone battery.

I know that seems difficult to understand, so here’s a simple analogy: you have a flashlight with a battery and a solar cell. The solar cell recharges the battery. If this were a Nikola Labs flashlight, you would recharge it by shining the flashlight onto the solar cell.

That is the simplest explanation of what the Nikola Labs cellphone case does, and illuminates the limitations of what it can do. If the ‘energy harvesting circuit’ collects power from the device it is recharging, it will reduce the transmission power of whatever is transmitting. With the cellphone case, you’re spending transmission power (plus efficiency losses) to recharge the battery. That means poorer reception and fewer bars. In the solar-recharging flashlight analogy, the flashlight would either be dimmer, or you could only use it part of the time.

It’s also why Nikola Labs claims their case will only recover 30% of the battery life of an iPhone 6; the battery isn’t solely dedicated to a transmitter – there’s a display and a CPU to account for in the power budget.

To Nikola Labs’ credit, this is at least a novel application of the RF energy harvesting trope that has been making its way around Kickstarter and tech blogs for a few years. Nearly every other RF harvesting idea that has been pitched in recent memory decouples the transmitter (or ‘generator’, I guess) with the product or receiver. The square cube law is an evil mistress, and if you’re wondering why these devices don’t work, [ch00f], a guy with an actual engineering degree, has a great writeup of one of these products over on Drop Kicker.

The Nikola Labs cellphone case bucks this trend by looking at the shortcomings of these devices; an RF rechargeable Bluetooth tag won’t work if you place it a foot away from a WiFi router, but it just might if you tape it to the antenna. This is the idea behind Nikola Labs’ invention: harvest energy from a few millimeters away from the cell phone’s antenna. According to Nikola Labs, their engineer, [Chi-Chih Chen] has a patent in the works for this. This patent application has not been published yet.

In theory, the Nikola Labs cellphone case will actually recharge your battery, but at a price: you’d be wasting your transmission power on recharging the battery. It’s a false economy that you’ll be able to fund on Kickstarter next month for $100 USD. If you’re only looking for more battery life, walk into any gas station, buy a $10 USB power bank/battery, and have enough portable power to recharge your iPhone battery to 100%. That’s not a sexy solution, it doesn’t reference [Nikola Tesla], and it’s not snake oil that tech media is lapping up like dogs. Pity.

Stuff Wireless Charging Into a Nook’s Crannies

Qi receiver for NookMany technologies that come about for one type of product make us want to extend it to other things. For instance, we’d like the ability to remotely unlock our front door when it’s raining or our hands are full. Once [MS3FGX] experienced Qi wireless charging with his Nexus 5, he wanted the ability to wirelessly charge all the things. The first gadget on the list was his Nook Simple Touch eReader, which he successfully retrofit with a Qi receiver.

Space is at a premium inside of most modern technology. As it turns out, there is a burgeoning market for shoving inductive charging receivers into things. [MS3FGX] decided to try a Qi receiver meant for a Samsung S3, and it actually fits very well behind the battery. He glued it down and then cut a channel in the battery tray for the wires.

[MS3FGX] went full hack with this one and wired it to the Nook’s USB port on the inside. He would have preferred a thinner wire, but used some from a 40-pin IDE cable with little trouble. After the operation was complete, he put it on the Qi pad and it started charging right away. To his delight, the battery increased 20% after an hour. And yes, he can still charge the Nook the traditional way without any issues.

If you want to add wireless charging to any phone cheaply and easily, we’ve got you covered.

Hackaday Links: January 5, 2014


While we can’t condone the actual use of this device, [Husam]’s portable WiFi jammer is actually pretty cool. It uses a Raspberry Pi and an Aircrack-ng compatible dongle to spam the airwaves with deauth packets. The entire device is packaged in a neat box with an Arduino-controlled LCD and RGB LEDs. Check out an imgur gallery here.

You can pick up a wireless phone charger real cheap from any of the usual internet outlets, but try finding one that’s also a phone stand. [Malcolm] created his own. He used a Qi charger from DealExtreme and attached it to a 3D printed phone stand.

A while back, [John] noticed an old tube radio in an antique store. No, he didn’t replace the guts with a Raspberry Pi and an SD card full of MP3s. He just brought it back to working condition. After fixing the wiring (no ground cord on these old things), repairing the speaker cone, putting some new twine on the tuner and replacing the caps, [John] has himself a new old radio. Here’s a video of the complete refurbishment.

Here’s a Sega Master System (pretty much a Game Gear) running on an STM32 dev board. Also included are some ROMs for some classic games – Sonic the Hedgehog, Castle of Illusion, and The Lion King. If you have this STM Discovery board you can grab the emulator right here.

[Spencer] wanted a longer battery life in his iPhone, so he did what any engineering student would do: he put another battery in parallel.

Breadboarding something with an AVR or MAX232? Print out some of these stickers and make sure you get the pinouts right. Thanks, [Marius].

Custom Wireless Headphone Charging Station


We’ve come to expect quite a lot of convenience from our technology, to the point where repeatedly plugging in a device for recharging can seem tedious. Hackaday regular [Valentin Ameres] decided to ditch the plugs and built his own wireless headphone charger. We’ve seen [Valentin’s] work before, and one thing’s for certain: this guy loves his laser cutter. And he should, considering it’s churned out key components for a gorgeous Arc Reactor replica and his Airsoft Turret. [Valentin] fired it up yet again to carve the charging stand out of acrylic, then used a small torch and the edge of a table to bend the stand into shape.

He sourced the needed coils online and soldered the receiving coil to a spare miniUSB plug. These components are glued onto a laser-cut acrylic attachment, which fits against the side of the headphone and is held in place by plugging directly into the earpiece’s miniUSB jack. The headphones rest on the laser-cut charging stand, which has an extrusion of acrylic on one side that holds the emitter coil in position against the receiver coil. [Valentin] also added a simple momentary switch at the top of the stand to activate both the emitter coil and a status LED when pressed by the headphones.

Stick around for a video of the build below, and check out some other headphone hacks, like adding a Bluetooth upgrade or making a custom pair out of construction earmuffs.

Continue reading “Custom Wireless Headphone Charging Station”

Adding wireless charging to any phone

The wireless charging options available on flagship phones is a great feature, but most of us aren’t rocking the latest and greatest cellphone. [Daniel] came up with a great mod that adds wireless charging to just about every cellphone ever, at a very low price and a few bits and bobs ordered off eBay.

[Daniel] used a Palm Touchstone inductive charger – available for a few bucks on eBay – along with an inductive charging circuit from a Palm Pixi. This charging circuit was designed to complement the Touchstone charger, and is simple enough to wire up; all [Dan] needed to do was put the coil and charging circuit near the charge, and it output 5 Volts to charge any phone.

To get the power from the charging circuit into his phone’s battery, [Daniel] simply wired the output of the coil’s circuit to the USB in on the phone. The space inside his S2 was pretty tight but he was able to come up with two ways to install the charging circuit, for use with either the stock back cover or a third-party case.

For anyone with a soldering iron, it’s a quick bit of work to add wireless charging to any phone. We’re loving [Dan]’s solution, as the Palm gear he used is so readily available on eBay and junk drawers the world over.

Inductive charging going mainstream

The recent announcement of Psyclone’s TouchCharge kit has us moderately excited. Though inductive charging has been used in electric toothbrushes for ages, we have yet to see it infiltrate the rest of our lives. The kit is a bit pricey at the moment, but it is a step in the right direction. Unfortunately, you have to have an adapter for your specific product and their selection is pretty limited right now. Why not make your own to power your devices?  Warning: it is written from the perspective of [Arnold Schwarzanegger].

Update: Is the TouchCharge kit inductive? It appears to require contacts to touch the base.