Business card draws [ch00f]’s logo


[ch00f] is at it again, expanding the horizons of the art of PCB business cards. This one draws his logo on any computer over a USB port.

The physical design of the card is heavily inspired by [Frank Zhao]’s card; both use an ATtiny85 and the V-USB package to handle the USB protocol and communications. Instead of typing words into a text editor like [Frank]’s, [ch00f]’s card draws the ch00ftech logo in MS Paint or other image editor.

There was a problem with simply emulating the mouse to draw a logo on the screen, though; because different computers have different mouse settings for acceleration, the ch00ftech logo was nearly always distorted. [ch00f] fixed that by emulating an absolute input device, basically turning his business card into a single-function pen tablet.

The logo was traced by hand and put into a few arrays in the firmware. Surprisingly, the logo didn’t take up much space – only 4k of the tiny85’s flash is used. There’s a lot more space for a more complicated drawing, but for now the simple ch00ftech logo (video after the break) will do.

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[ch00ftech] Visits a Shenzhen Market

On a business trip, [ch00ftech] visited a Shenzhen electronics market and documented the trip. Some of the attractions included multiple Apple stores of questionable authenticity, stores selling PC components with no manuals, drivers, or packaging, and a variety of LEDs and lasers.

[ch00ftech] showed off the loot from the trip, including breadboards, perf boards, LED matrices, and an RFID reader all for very low prices. There’s also the Class 4 laser pointer that cost about $120 and has a power output of “between 500 mW and 8000 mW.” Given the 500 mW power restriction on lasers sold in the US, it’s fair to say that this thing should be handled with care. Hopefully the included safety classes actually block the specific wavelength of the laser.

The staff in these stores were very knowledgeable and knew part numbers and inventories by memory. One of the biggest surprises was just how low the prices were.  While Radio Shack has started to carry some more parts for hackers, it seems that nothing stateside can compare these Chinese electronics markets.

Pneumatic Pen Gun is Fit for James Bond

The James Bond franchise is well-known for many things, but perhaps most important to us hackers are the gadgets. Bond always had an awesome gadget that somehow was exactly the thing he needed to get out of a jam. [hw97karbine’s] latest project would fit right into an old Bond flick. He’s managed to build a single-shot pellet gun that looks like a pen.

[hw97karbine] started out by cutting the body from a tube of carbon fiber. He used a hacksaw to do the cutting, and then cleaned up the edges on a lathe. A barrel was cut from a piece of brass tubing with a smaller diameter. These two tubes will eventually sit one inside of the other. A custom front end cap was machined from brass. One end is ribbed and glued into the carbon fiber tube. The barrel is also glued to this end of the front cap, though it’s glued to the inside of the cap. The other end of the cap has 1/8″ BSP threads cut into it in order to allow for attachments.

A rear end cap is machined from Delrin. This piece also has a Delrin piston placed inside. The piston has a small piece of rubber used as a gasket. This piston valve is what allows the gun to operate. The rear cap gets glued into place and attached to a Schrader valve, removed from an automotive tire valve stem.

To pressurize the system, a bicycle pump is attached to the Schrader valve. This pushes the piston up against the barrel, preventing any of the air from escaping. The piston doesn’t make a perfect seal, so air leaks around it and pressurizes the carbon fiber tube. The Schrader valve prevents the air from leaking out of the pen body. A special machined button was threaded onto the Schrader valve. When the button is pressed, the air escapes; the sudden pressure imbalance causes the piston to shoot backwards, opening up a path for the air to escape through the barrel. This escaping air launches the projectile. The whole process is explained better with an animation.

Now, the question left in our mind: is this the same pressure imbalance concept that was used in that vacuum pressure bazooka we saw a couple years back?

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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.

1337-sp34k Keyboard

What started off as a quick prank-hack to re-map a colleague’s keyboard turned into a deep dive in understanding how keyboards work. [ch00f] and his other work place colleagues are in a habit of pulling pranks on each other. When [ch00f]’s buddy, who is an avid gamer and montage parody 1337-sp34k (leet speak) fan, went off on a holiday, [ch00f] set about re-mapping his friend’s keyboard to make it spit out words his friend uses a lot – “SWAG” “YOLO” and “420”. But remapping in software is too simple, his hack is a hardware remapping!

The keyboard in question used mechanical keys mounted on a keyboard sized PCB. Further, it was single sided, with jumper links used in place of front side tracks. This made hacking easier. The plan was to use keys not commonly used – Scroll Lock, Print Screen, and Pause/Break – and get them to print out the words instead. The signal tracks from these three keys were cut away and replaced with outputs from a microcontroller. The original connections were also routed to the microcontroller, and a toggle switch used to select between the remapped and original versions. This was eventually not implemented due to a lack of space to install the toggle switch. [ch00f] decided to just replace the keyboard if his friend complained about the hack. A bit of work on the ATMega PCB and firmware, and he was able to get the selected keys to type out SWAG, YOLO and 420.

And this is where a whole can of worms opened up. [ch00f] delves in to an explanation on the various issues at hand – keyboard scanning/multiplexing, how body-diodes in switching FET’s affected the scanning, ghosting and the use of blocking diodes. Towards the end, he just had the word SWAG activated by pressing the Pause/Break key. But he does get to the bottom of why the keyboard was behaving odd after he had wired in his hack, which makes for some interesting reading. Don’t miss the video of the hack in action after the break.

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Towards More Interesting Instant Cameras

When [Ch00f] was getting jeans rung up at Nordstroms, he noticed how fast thermal receipt printers can put an image on a piece of paper. This observation isn’t unique to the circles [Ch00f] frequents – there are a few small receipt paper printers out there that connect to the Internet, iPhones, and a whole bunch of other Kickstarter-friendly keyword devices.

Nevertheless, a device that can make a hard copy of an image quickly and cheaply isn’t something you just stop thinking about. After rolling the concept around in his head for a few years, [Ch00f] finally came up with the perfect build – a camera.

The hardware for the build is based around an STM32F4 Discovery board. It’s a bit overpowered for this sort of application, and this is one of [Ch00f]’s first adventures in ARM-land. The rest of the hardware consists of a thermal receipt printer and a JPEG camera, the latter of which replaced a cellphone CMOS camera module that was lost in a move.

A custom camera requires a custom enclosure, and for this [Ch00f] made something remarkable. The entire enclosure is CNC milled out of a beautiful piece of figured walnut. The end result looks far too good for a prototype, but it does polish up nicely with a bit of linseed oil.

Now [Ch00f] has an instant camera that takes the idea of a Polaroid and turns it into something that produces a print for tenths of a cent. There’s a time-lapse function – just a zip tie on the shutter button – filters with the help of highlighters, and the ability to record movies in flipbook format.

It’s a great project, and also something that will make for a great crowdfunding campaign. [Ch00f] has already started work on this. He already has a sleek, modern-looking website that requires far too much scrolling than should be necessary – the first step to a winning Kickstarter. [Ch00f] also learned a lot about ARMs, DMA, dithering, gamma correction, and the JPEG format, but that’s not going to get anyone to open up their wallet. You know what will? A slick video. You’ll find that below.

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Hackaday Links: October 19, 2014

Introducing the Hayes Smartmodem 1200. The era of the single station microcomputer…. is over. The Hayes Smartmodem offers advanced features like auto answer and auto dial. Now if we could only find an ‘RS-232 Computer.’

Have a 3D printer and an old router? How about controlling your printer with Octoprint? For some cases, it might be better than using a Raspberry Pi and OctoPi, but you won’t get a camera for streaming pics of your builds to the web.

Last year, [CNLohr] built a microscope slide Minecraft thing and in the process created the smallest Minecraft server ever. The record has now been bested with the Intel Edison. There’s a bit of work to install Java, but the performance is pretty good for one player. Bonus: Minecraft is a single threaded app, so you have another core for garbage collection.

Remember the Scribble pen, that showed just how gullible people are and how crappy tech journalism is? They’re back with a beta program. A mere $15 guarantees you a scribble pen for their beta program. I wouldn’t give these guys $15 of someone else’s money, but lucky for us [ch00f] bit the bullet. He’ll be updating everyone on the status of his fifteen dollars, I’m sure.

Hey, guess what will eventually be in the Hackaday store? Keycaps for your mechanical keyboard. Yes, we actually figured out a way to do this that makes sense and won’t lose money. Pick your favorite, or suggest new ones in the comments: