A Close Look At USB Power

May 22, 2021 by Tom Nardi 29 Comments

It’s not a stretch to say that most devices these days have settled on USB as their power source of choice. While we imagine you’ll still be running into the occasional wall wart and barrel jack for the foreseeable future, at least we’re getting closer to a unified charging and power delivery technology. But are all USB chargers and cables created equal?

The answer, of course, is no. But the anecdotal information we all have about dud USB gear is just that, which is why [Igor Brkić] wanted to take a more scientific approach. Inspired by the lighting bolt icon the Raspberry Pi will flash on screen when the voltage drops too low, he set out to make a proper examination of various USB chargers and cables to see which ones aren’t carrying their weight.

In the first half of his investigation, [Igor] tests four fairly typical USB chargers with his TENMA 72-13200 electronic load. Two of them were name brand, and the other just cheap clones. He was surprised to find that all of the power supplies not only met their rated specifications, but in most cases, over-performed by a fair amount. For example the Lenovo branded charger that was rated for only 1 A was still putting out a solid 5 V at 1.7 A. Of course there’s no telling what would happen if you ran them that high for hours or days at a time, but it does speak to their short-term burst capability at least.

He then moved onto the USB cables, were things started to fall apart. The three generic cables saw significant voltage drops even at currents as low as 0.1 A, though the name brand cable with 20 AWG power wires did fare a bit better. But by .5 A they were all significantly below 5 V, and at 1 A, forget about it. Pulling anything more than that through these cables is a non-starter, and in general, you’ll need to put at least 5.2 V in if you want to actually run a USB device on the other side.

Admittedly this might not be groundbreaking research, but we appreciate [Igor] taking a scientific approach and tabulating all the information. If you’re still getting low voltage warnings on the Pi after swapping out your cheapo cables, then maybe the problem is actually elsewhere.

Hackaday Podcast 077: Secret Life Of SD Cards, Mining Minecraft’s Secret Seed, BadPower Is Bad, And Sailing A Sea Of Neon

July 24, 2020 by Mike Szczys 3 Comments

Hackaday editors Mike Szczys and Elliot Williams are deep in the hacks this week. What if making your own display matrix meant a microcontroller board for every pixel? That’s the gist of this incredible neon display. There’s a lot of dark art poured into the slivers of microSD cards and this week saw multiple hacks digging into the hidden test pads of these devices. You’ve heard of Folding@Home, but what about Minecraft@Home, the effort to find world seeds from screenshots. And when USB chargers have exposed and rewritable firmware, what could possibly go wrong?

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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Micro Wind Turbine For Hikers

March 18, 2017 by Adam Fabio 77 Comments

[Nils Ferber] is a product designer from Germany. His portfolio includes everything from kitchen appliances to backpacks. One project, though, has generated a bit of attention. It’s a micro wind turbine aimed at long distance hikers.

Even on the trail, electronics have become a necessity. From GPS units to satellite phones, to ebook readers. Carrying extra batteries means more pack weight, so many hikers utilize solar panels. The problem is that when the sun is up, hikers are on the move – not very conducive to deploying a solar array. The Wind, however, blows all through the night.

[Nils] used carbon fiber tube, ripstop nylon, and techniques more often found in kite building to create his device. The turbine starts as a small cylindrical pack. Deploying it takes only a few minutes of opening panels and rigging guy wires. Once deployed, the turbine is ready to go.

While this is just a prototype, [Nils] claims it generates 5 Watts at a wind speed of 18 km/h, which can be used to charge internal batteries, or sent directly to any USB device. That seems a bit low for such a stiff wind, but again, this is just a prototype. Could you do better? Tell us in the comments! If you’re looking for a DIY wind generator on a slightly larger scale, you could just build one from bike parts.

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Slimline USB Charger For Tiny Ham Radios

September 5, 2015 by Dan Maloney 12 Comments

The recent trend to smaller and smaller handy talkie (HT) transceivers is approaching the limits of the human interface. Sure, engineers could probably continue shrinking the Baofeng and Wouxun HTs further, but pretty soon they’ll just be too small to operate. And it’s getting to the point where the accessories, particularly the battery charging trays, are getting bulkier than the radios. With that in mind, [Mads Hobye] decided to slim down his backpacking loadout by designing a slimline USB charger for his Baofeng HT.

Lacking an external charging jack but sporting a 3.7 volt battery pack with exposed charging terminals on the rear, [Mads] cleverly capitalized on the belt clip to apply spring tension to a laser-cut acrylic plate. A pair of bolts makes contact with the charging terminals on the battery pack, and the attached USB cable allows him to connect to an off-the-shelf 3.7 volt LiPo USB charger, easy to come by in multicopter circles. YMMV – the Baofeng UV-5R dual-band HT sitting on my desk has a 7.4 volt battery pack, so I’d have to make some adjustments. But you have to applaud the simplicity of the build and its packability relative to the OEM charging setup.

This isn’t the first time we’ve seen [Mads] on Hackaday. He and the FabLab RUC crew were recently featured with their open-source robotic arm.

Crack Open A USB Car Charger To Make It A Variable DC-DC Converter

August 13, 2015 by Nava Whiteford 23 Comments

[Boolean90] hacked a cheap USB car charger into a variable power supply. His proof of concept is to use this as a variable-speed motor controller. The best part is that nothing is being abused, the regulator inside is still running within manufacturer’s spec.

While we’ve seen similar hacks before, [Boolean90]s video is pretty cool and provides a nice insight into the components used in these cheap devices. Rather than a linear regulator, which would dissipate too much heat the device uses a common jelybean MC34063A (PDF) switching DC-DC converter which costs about 10 cents on eBay (about two dollars for twenty, shipped). Here it’s used to step the car batteries 12 volts down to 5, but can also be used in step-up and inverting configurations.

Like all switching buck converters the MC34063A uses a PWM (pulse width modulated) signal to drive an inductor and capacitor, which effectively form an LC filter. By controlling the pulse width, the output voltage can be regulated. [Afrotechmods] has a great tutorial on the basic principle. The regulation is controlled by feedback resistors. [Boolean90] simply added a variable resistor to allow the output voltage to be controlled.

Neat hack [Boolean90]! Continue reading “Crack Open A USB Car Charger To Make It A Variable DC-DC Converter” →

Insane 33 Port USB Charger

July 8, 2015 by Anool Mahidharia 67 Comments

Like it or not, Hackers gonna hack. And when your hackerspace has someone who looks like Doc Brown from Back to the Future, the builds can get a bit weird, like this Hack42 FestivalCharger.

The Hack42 hackerspace in Arnhem, The Netherlands had collected a large number of TP-Link 5V USB chargers – but all of them had the North American NEMA plug (flat, 2 pin) which wouldn’t fit the Schuko sockets prevalent in The Netherlands. [Simon “MacSimski” Claessen] decided to whip out his giant soldering iron and use it to solder two long pieces of welding filler metal rods to 33 of the chargers, effectively wiring them up in parallel. He did apply his obvious skill and experience to good use. For one, the diameter of the filler metal rods he used were just about the right size to fit in the ~~Shucko~~ Schuko socket. And the gap between the two turned out to be the right distance too, thus creating a sort of ~~Schucko~~ Schuko plug. All that was needed to power up all the chargers was to connect a socket extension to the FestivalCharger. The unit was built to allow crowds of festival-goers to charge their phones and battery-powered gadgets simultaneously. To make sure the visitors didn’t get electrocuted, he used a piece of PVC pipe to cover up the exposed pins and keep it all safe.

Thanks to Hack42 member [Dennis van Zuijlekom] for sending in this tip.

Keystroke Sniffer Hides As A Wall Wart, Is Scary

January 14, 2015 by Bryan Cockfield 79 Comments

For those of us who worry about the security of our wireless devices, every now and then something comes along that scares even the already-paranoid. The latest is a device from [Samy] that is able to log the keystrokes from Microsoft keyboards by sniffing and decrypting the RF signals used in the keyboard’s wireless protocol. Oh, and the entire device is camouflaged as a USB wall wart-style power adapter.

The device is made possible by an Arduino or Teensy hooked up to an NRF24L01+ 2.4GHz RF chip that does the sniffing. Once the firmware for the Arduino is loaded, the two chips plus a USB charging circuit (for charging USB devices and maintaining the camouflage) are stuffed with a lithium battery into a plastic shell from a larger USB charger. The options for retrieving the sniffed data are either an SPI Serial Flash chip or a GSM module for sending the data automatically via SMS.

The scary thing here isn’t so much that this device exists, but that encryption for Microsoft keyboards was less than stellar and provides little more than a false sense of security. This also serves as a wake-up call that the things we don’t even give a passing glance at might be exactly where a less-honorable person might look to exploit whatever information they can get their hands on. Continue past the break for a video of this device in action, and be sure to check out the project in more detail, including source code and schematics, on [Samy]’s webpage.

Thanks to [Juddy] for the tip!

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