[Justin]’s friend [Steve] injured his spine a while ago, and after asking what would make [Steve]’s life simpler, the answer was easy. [Steve] missed reading books. Sure, e-readers exist, but you still need to turn the page. Now [Steve] can do that with his voice thanks to some microcontrollers, Bluetooth modules, and a voice recognition module.
A voice-activated page turner wasn’t the first attempt at giving [Steve] the ability to turn a page on a Kindle. The first prototype was a big blue button that sent a keyboard code for ‘right arrow’ over Bluetooth, turning a book one page at a time. This worked well until multiple pages turned, and with no back button it was a major nuisance.
After playing with the voice recognition in an Amazon Echo, [Steve] and [Justin] wondered if the same voice recognition technology could be applied to page turns on a Kindle. With a voice recognition Arduino shield from SparkFun it was easy to detect a ‘page down’ command. A Bluetooth module sends HID commands to a Kindle, allowing [Steve] to read a book with only his voice.
[Justin] put all the design files for this build up on Github.
[Craig] sent in this tip about a simple hack he built to convert an old analog micro-ammeter into a thermometer using a few parts. There’s a certain charm to retro analog meters, and there was enough space inside the old meter to accommodate the tiny breadboarded circuit and the three AA batteries to convert it into a cool looking centerpiece which is useful too!
He used the 3-pin MCP9700 analog temperature sensor connected to a LTC1541 – a combined comparator, op-amp and band gap reference voltage all rolled into one package. The thermometer displays 1uA per degree Celsius, has an output of 1mV per degree Celsius for external temperature monitoring / data logging, and draws just about 20uA. While the build itself is pretty simple, [Craig] took the time to walk through every design decision he made in the video after the break. This starts with the design for his circuit, and moves on to the selection of parts and their values. The video is a must-watch for anyone wanting to learn more about precision op-amp based designs.
The three batteries will drain over time, and a circuit like this one requires a stable reference voltage. That is taken care by the bandgap reference voltage from the LTC1541. This eliminates the use of additional voltage regulators, and allows the circuit to work from 4.5V down to about 3.3V. Check the video after the break to listen to [Craig] describe how it works. We’re not sure how quickly it responds to changes in ambient temperature since the sensor is enclosed inside the meter, so maybe some vents at the back, or bringing out the sensor might be a good idea.
Continue reading “Vintage Microammeter Now Tells Temperature”
The embossing process used in the creation of some of your fancier wedding invitations and business cards is an interesting one. It’s often called thermography or thermographic printing. Slow-drying, wet ink is applied to a substrate. The ink is dusted with a thermoplastic polymer called embossing powder, and a heat source raises the ink while drying it.
Commercial embossing powder costs about $10 an ounce. As [Ken] discovered, its manufacture is quite closed-source to boot. He set about creating his own embossing powder, and succeeded with a combination of commonly available floor finish and distilled white vinegar. A standard-sized bottle of floor finish yielded about four ounces of homemade embossing powder.
How does this work? The floor finish is an acrylic-based stable emulsion. Adding vinegar destabilizes the emulsion, decreasing its pH and setting the polymer free. It’s a fairly fast process, which you can see in the second video that accompanies [Ken]’s write up. From there, it’s mostly a matter of straining the material, letting it dry, and pulverizing the coarse matter into powder. In the first video, [Ken] performs a comparison test of Ranger, a commercial powder, and his own concoction.
For a completely different take on home embossing, check out this soda-can-turned-keepsake-box.
[Andrew Klein] knows the pain of building drawers from plywood. It can be a pain to get all of the pieces measured and cut just right. Then you have to line them up, glue them together, and clamp them perfectly. It’s time-consuming and frustrating. Then one day it hit him that he might be able to make the whole process much easier using a custom saw blade.
The the video below, [Andrew] does a great job explaining how the concept works using a piece of paper. The trick is that the plywood must be cut in a very specific shape. This shape results in the plywood just barely being held together, almost as if it’s hinged. The resulting groove can then be filled with wood glue, and the plywood is folded over on itself. This folding process leaves no gaps in the wood and results in a strong joint. Luckily this special shape can be cut with a specialized saw blade.
This new process removes the requirement of having five separate pieces for a drawer. Instead, only four cuts are needed on a single piece of square plywood. The corners are then removed with a razor blade and all four sides are folded up and into place. [Andrew] shows that his prototype blade needs a little bit of work, but he’s so hopeful that this new invention will be useful to others. Continue reading “Smarter-than-wood Saw Blade Makes Perfect Foldable Joints”
The United States Postal Service (USPS) is fixture of American life with its roots going back to colonial times. It operates the largest civilian vehicle fleet in the world, delivering about half a billion pieces of mail a day. As with any system of that size it’s always interesting to peek and poke at to see how it works. Unfortunately, it’s not as fun to hack as the phone system once was, but that didn’t stop some
hackers pranksters from giving it a go.
So how do you “hack” the mail? Simple, by testing its own rules. The folks at [Improbable Research] did just that and some of the results were interesting enough that we thought we would share them with you. They started with testing valuable items to see how honest USPS employees would be. First they attached a $20 bill to a post card. Yep, it showed up just 4 days later, and the money was still there. So they decided to see if sentimental items, that normally would be refused by the postal service, might skate through. They were able to send both an un-boxed single rose, and a human tooth (in a clear plastic box) without issue. Both arrived just fine, despite the rule that human remains are not allowed to be shipped via USPS. We’ll let you read some of the other items they tried.
So the next time you’re in Hawaii, forget about sending that generic, boring post card back home. Instead, slap some stamps on a coconut to let your friends know exactly how much fun you’re having.
With that said, we wouldn’t be doing our job looking out for our readers if we didn’t mention that before you try anything too outlandish, you can be fined for abuse of the postal system, even as a recipient. There was a fair amount of fallout when those guys sent a camera through the mail. Have fun, but not at someone else’s expense.
Back in 2012, [tmbinc] discovered a neat little undocumented feature in the Xilinx ISE: the ability to use TCP/IP instead of JTAG cables. [tmbinc] was working on an Open Hardware USB analyzer and discovered the nearly undocumented Xilinx Virtual Cable, a single ‘shift’ command that opens up a TCP connection and sends JTAG data out to another computer on the network. It’s extraordinarily useful, [tmbinc] wrote a daemon for this tool, and everything was right with the world.
Yesterday, [tmbinc] discovered the Xilinx Virtual Cable again, this time in one of Xilinx’s Github repos. The code was extraordinarily familiar, and looking closer at a few of the revisions, he saw it was very similar to code he had written three years ago.
The offending revision in the Xilinx repo is nearly identical to [tmbinc]’s Xilinx Virtual Cable Driver daemon. Variable names are the same, the variables are declared in the same order, and apart from whitespace, code conventions are the same. This is not to say someone at Xilinx stole code from [tmbinc], but if this were a computer science lab, there would be an academic disciplinary hearing. What’s worse, Xilinx plastered their copyright notice at the top of the code.
In an issue [tmbinc] raised, he said he was flattered, but clarified that his code was developed entirely from scratch. He believes the Xilinx code was derived from his own code written three years ago. Since [tmbinc]’s code was uploaded without a license, it defaulted to All Rights Reserved. This does not bode well for the Xilinx legal department.
In any event, you really, really have to wonder what Xilinx’s internal documentation looks like if a random person on the Internet can discover a barely-documented protocol, write a daemon, put it on the Internet, and have someone at Xilinx use that code.
Thanks to the anonymous tipster for sending this into the Hackaday tip jar.
Even though most of us know logic gates like the back of our hands, we just found this awesome explanation video you can use to teach kids in a very fun way — Using nothing but dominoes.
Produced by [Numberphile], our host sets up various “circuits” using dominoes to explain all the various logic gates. Some of the patterns are a bit tricky to setup since you actually have to set up timing based on the spacing of the dominoes — makes us wonder how many bloopers there were!
But don’t take our word for it, it’s well worth a watch after the break.
Continue reading “Learning Logic Gates With Dominos”