Sound Card Tachometer Rises From the Junkbox


We love writing up projects that re-use lots of old parts. In fact, we save the links and use them as defense when our significant other complains about the “junk” in the basement. No, that tactic hasn’t ever worked, but we’re going to keep trying. Case in point, [Wotboa] needed a non-contact tachometer. There are plenty of commercial products which do just that. After consulting his parts bin, [wotboa] realized he had everything he needed to hack out his own. An IR break beam sensor from an old printer was a perfect fit in an aluminum tube. With the outer shell removed, the emitter and detector were mounted in the nylon shell of an old PC power supply connector, effectively turning them pair into a reflective sensor. To amplify the circuit, [wotboa] used a simple 2n2222 transistor circuit. The key is to keep the voltage seen by the sound card the range of a line level signal. This was accomplished by adding a 2.2 Megohm resistor in line with the output. [wotboa] drew his schematic in eagle, and etched his own PCB for the project. Even the tachometer’s case came from the parts bin. An old wall wart power supply gave up its shell for the cause, though [wotboa] is saving the transformer for another project.

For sensing, [wotba] used [Christian Zeitnitz's] Soundcard Oscilloscope software.  Measuring the RPM of the device under test is simply a matter of determining the frequency of the signal and multiplying by 60. A 400 Hz signal would correspond to a shaft turning at 24,000 RPM. The circuit performs well in the range of RPM [wotboa] needs, but using a sound card does have its limits. The signals on the scope look a bit distorted from the square waves one would expect. This is due to the AC coupled nature of sound cards. As the signal approaches DC, the waveform will become more distorted. One possible fix for this would be to remove the AC coupling capacitor on the sound card’s input. With the capacitor removed, an op amp buffer would be a good idea to prevent damage to the sound card.

[Via Instructables]

QFN Breakout Is Easy On the Eyes, Wallet

What do you do when you have ATMega328s in QFN package burning a hole in your bug box, but you aren’t set up for SMD and have limited access to parts? You man up and do what [Djpanjan] did: make your own breakout board with solder, right angle header, and many tiny, beautiful wires.

[Djpanjan] says the process is a simple one that requires great concentration. Once he had it broken out, he covered the wires with hot glue to make sure they all stay in place. He programmed it using an Arduino as an ISP and he was able to run the blink sketch without issue. He blinked all the output pins to make sure there were no shorts.

[Djpanjan] says that if he can’t get a breakout for his LQFP-144, he’s going to make his own again. Good luck, [Djpanjan]. We’re all counting on you.

If you’re set up for SMD and etching, there’s always the surface mount breakout route. If not, you can always use magnet wire and protoboard.

Lichtspiel crosses board games with video games


Video games are amazing these days. Cinemagraphic game play, incredible accelerated graphics, you name it. The average tabletop board game though, has not received the benefit of all this technology. [Marcel] hopes to provide some options for changing that with Lichtspiel, an Interactive Digital Boardgame. Lichtspiel uses a Philips Pico-Beamer projector to project the game board onto a white surface. A camera (either a Raspberry Pi camera module or a Logitech USB webcam) then picks up the players interactions with the game board. Actual interaction is done with small black chips. When a player moves their chip, the vision system sends the x,y coordinates main processor. The game then changes based upon the chip position. [Marcel's] video shows two demonstrations, a matrix style board game simulation for two and a co-operative asteroids style game. In the asteroids style game one player moves the ship while the other aims the weapons.

We can’t help but see the similarities between this system and the board game demos for castAR , though we feel they fill different niches. Lichtspiel does away with 3D, and by doing so doesn’t require projection glasses to play. Lichtspiel definitely has possibilities. We’d love to see [Marcel] open up his software design so that it can be further developed.

[Read more...]

Fixing the Unfixable: Pebble Smartwatch Screen Replacement


[Colt] found himself with a broken Pebble, so he fixed it. The Pebble watch really ignited the smartwatch world with its record-breaking Kickstarter campaign. Working on the Pebble has proved to be frustrating experience for hardware hackers though. Ifixit’s teardown revealed the Pebble extremely difficult to repair. This isn’t due to some evil plan by the smartwatch gods to keep us from repairing our toys. It’s a problem that comes from stuffing a lot electronics into a small waterproof package. [Colt's] problem was a bad screen. Pebble has a few known screen issues with their early models. Blinking screens, snow, and outright failed screens seemed to happen at an alarming rate as the early Kickstarter editions landed. Thankfully all those issues were corrected and replacements sent to the unlucky owners.

The actual screen used in the Pebble is a Sharp Memory LCD. Memory is an apt name as the screens actually behave as a SPI attached write only memory. Sharp sells flexible printed circuit (FPC) versions of the LCDs to aid in debugging. For space constrained designs though, an elastomeric or “zebra strip” connector is the common way to go. Alternating bands of conductive and insulating material make electrical connections between the Pebble’s circuit board and the conductive portions of the LCD glass.

[Colt] found himself with a dead screen out of warranty, so he decided to attempt a screen replacement. He found a replacement screen from Mouser, and proceeded to remove the top case of his watch. The top plastic case seems to be the hardest part of getting into a Pebble. It appears to be bonded with a glue that is stronger than the plastic itself. [Colt] broke the glass of his screen during the removal, which wasn’t a big deal as it was already dead. Prying only destroyed the top plastic, so he broke out a rotary tool which made quick work of the plastic.  The new screen worked perfectly, but had to be held in just the right position over its zebra connector. Some waterproof epoxy held it in place permanently. The next step was a new top cover. An old flip phone donated its plastic shell to the effort, and hot glue kept everything in place. [Colt] finished his work with a couple of layers of model paint. The result certainly isn’t as pretty or waterproof as the original. It is functional though, and about $120 USD cheaper than buying a new Pebble.

[Read more...]

ReSCan — Automated Resistor Identification!

resistor id

Need a quick and easy way to sort through a few hundred random resistors? You could do them one at a time by reading the color codes yourself… or you could get a machine to do it for you!

When [Robert] was faced with a pile of unsorted resistors he quickly decided he did not have the patience to sort them manually. So, he started by writing an Android app using OpenCV to detect and identify resistor color codes. The problem is, most phones have trouble focusing at short distances — and since resistors are so small, holding the phone farther back results in color rings only being a few pixels wide — not the greatest for image recognition!

So, he started again on his computer, using a cheap LED-lit webcam instead. He wrote the app in java so he could re-use parts of the code from the Android app. It seems to work pretty well — check it out in the following video! This would be perfect to pair up with your illuminated storage bin hack.

[Read more...]

Light Your Way to the Correct Resistor


Who doesn’t have issues with component storage (seriously, tell us your secret in the comments)? IF you can get your spare parts organized, it’s still quite difficult to figure out where you actually squirreled them away. Labeling drawers is one thing, but what if you have hundreds or thousands of drawers (we’re looking at you, every Hackerspace that’s been around for more than a few months). This project adds a digital cue to well-organized parts storage by lighting up the component drawer for stock selected from your computerized inventory (translated).

The idea is that all of your parts are assigned a drawer space on the computer. When you go into the index and select a part, the assigned drawer is illuminated by an LED. The setup here is a breakout board for an I2C LED driver which interfaces with a Raspberry Pi, but the concept should be easy to implement with just about any system.

Need help getting to the point where you’re organized enough to implement this? So do we. Maybe revisiting this storage roundup will help.

Shenzhen Tour and UnHuman Soldering Classes with DP


If you’re free the first week of April and don’t mind sitting on a plane for a looooong time you should check out the Hacker Camp that Dangerous Prototypes is planning. We’re sure you remember [Ian Lesnet] who is a Hackaday Alum, creator of the Bus Pirate, and geeky world traveler. Now’s your chance to try out what to him is a way of life.

The event is April 3-5 in Shenzhen, China. Although marketed as a “Hacker Camp”, to us it sounds more like training for those interested in running hardware companies that use the Shenzhen manufacturing district as the anchor of their supply chain. Part of the prep-work for the trip includes submitting board files which will be fabbed and ready for you on the first day. [Ian] and his crew will be your guides for the culture of the area; complete with meals and bar time. But there are also soldering workshops as part of the package. Don’t pooh-pooh the idea. This is unhuman soldering… BGA and QFN soldering instruction from the people who repair cellphones and other microelectronics.

This [Rick Steves] style adventure is the first that we remember hearing about that targets the open hardware community. But we must admit, it sounds like a lot more fun than a European river cruise!

[Thanks Akiba]