Opto-Isolating Automatic Cat Feeder Problems

October 7, 2017 by 22 Comments

When you buy an off-the-shelf automatic cat feeder, you might well expect it to do the one thing it’s supposed to do. Feed the cat. Well, at least as long as you do your part by keeping it filled with food nuggets. [Stephen] had the sneaking suspicion that his feeder was slacking occasionally, and set out to prove this theory.

He had a few ideas for approaching the investigation. One was to set up a web cam, but that proved unreliable. Another idea was to log the weight changes of the food bowl. This seemed like a possibility because the reading would change dramatically whenever it was filled. The method he settled on is a good one, too — monitor the motor’s activity and look for holes. After all, the motor only runs when it’s feeding time.

The design is based around a smart door/window alarm, which is little more than a reed switch with networking capabilities. [Stephen] wired up an opto-isolator so that when the motor runs, the reed switch is triggered but not fried, and the event gets logged in Google Sheets. Any missed meals are weeded out with a script that alerts [Stephen] via email and text that his poor kitty is hungry.

If [Stephen] ever wants to build his own cat feeder, we have plenty of designs for inspiration.

An Old Video Game Controller On Even Older Computer

October 6, 2017 by 13 Comments

For those of us not old enough to remember, and also probably living in the States, there was a relatively obscure computer built by Microsoft in the early 80s that had the strong Commodore/Atari vibe of computers that were produced before PCs took over. It was known as the MSX and only saw limited release in the US, although was popular in Japan and elsewhere. If you happen to have one of these and you’d like to play some video games on it, though, there’s now a driver (of sorts) for SNES controllers.

While the usefulness of this hack for others may not help too many people, the simplicity of the project is elegant for such “ancient” technology. The project takes advantage of some quirks in BASIC for reading a touch-pad digitizer connected to the joystick port using the SPI protocol. This is similar enough to the protocol used by NES/SNES controllers that it’s about as plug-and-play as 80s and 90s hardware can get. From there, the old game pad can be used for anything that the MSX joystick could be used for.

We’ve seen a handful of projects involving the MSX, so while it’s not as popular as Apple or Commodore, it’s not entirely forgotten, either. In fact, this isn’t even the first time someone has retrofitted a newer gaming controller to an MSX: the Wii Nunchuck already works for these machines.

Fighting Machine Tool Chatter With A 555 Timer

October 6, 2017 by 32 Comments

Vibration is a fact of life in almost every machining operation. Whether you’re milling, drilling, turning, or grinding, vibration can result in chatter that can ruin a part. Fighting chatter has generally been a matter of adding more mass to the machine, but if you’re clever about things, chatter reduction can be accomplished electronically, too. (YouTube, embedded below.)

When you know a little something about resonance, machine vibration and chatter start to make sense. [AvE] spends quite a bit of time explaining and demonstrating resonance in the video — fair warning about his usual salty shop language. His goal with the demo is to show that chatter comes from continued excitation of a flexible beam, which in this case is a piece of stock in the lathe chuck with no tailstock support. The idea is that by rapidly varying the speed of the lathe slightly, the system never spends very long at the resonant frequency. His method relies on a variable-frequency drive (VFD) with programmable IO pins. A simple 555 timer board drives a relay to toggle the IO pins on and off, cycling the VFD up and down by a couple of hertz. The resulting 100 RPM change in spindle speed as the timer cycles reduces the amount of time spent at the resonant frequency. The results don’t look too bad — not perfect, but a definite improvement.

It’s an interesting technique to keep in mind, and a big step up from the usual technique of more mass.

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Tape Cutting Bot Trims The Tedium

October 6, 2017 by 12 Comments

If you have ever had to assemble a batch of electronic kits, you will know the tedious nature of cutting the tape containing your components. It’s easy enough to count four or five surface-mount resistors and snip them off with a pair of scissors once or twice, but when you are faced with repeating the task a hundred or more times, its allure begins to pale.

[Overflo] faced just such a problem when assembling hundreds of kits for a workshop at the upcoming 34C3 event in Germany. The solution? A tape-cutting robot, of course! (YouTube video, embedded below.)

At the heart of the machine is a pair of scissors operated by a stepper motor, snipping away at the component tape fed by another stepper. An infra-red light barrier sensor counts sprocket holes, and the whole is under the control of an Arduino Pro Mini. An especially clever trick is that the strip passes over a marker pen, allowing different components in a kit to be identified by a color code.

This isn’t the first such approach to this problem we’ve encountered, here’s one that cuts component tape with a laser.

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Hackerfarm Brings Light To Puerto Rico

October 6, 2017 by 64 Comments

Puerto Rico has a long road to recovery, and part of this is the damaged infrastructure: much of the electricity distribution network was destroyed, and will take months or years to rebuild. The Japanese hacker group [Hackerfarm], founded by Hackaday friend [Akiba], is looking to help by sending some of their solar lanterns to provide off-grid light.

They’ve already shipped one batch, and are using the proceeds from sales of these paper lanterns to send more of them to Puerto Rico, where they will be given out to those who need them. The group has carried out similar projects before, distributing lanterns to Tsunami-hit areas of Japan and to Rwanda, where a women’s group builds and sells the lanterns. It seems like a great cause, and the design of the lanterns is pretty neat. We love that they provide an introduction to soldering and serve a higher purpose at the same time.

We’ve mentioned Hackerfarm before, both as part of a growing rural hackerspace scene, and because of their insane EL-wire creations and choreography. And [Akiba] gave a great talk at last year’s Supercon where he discussed the ins and outs of getting virtually anything done in Shenzhen. Check it out if you haven’t already.

Hackaday Prize Entry: Economical Bionic Leg

October 6, 2017 by 9 Comments

When it comes to high-tech bionic legs for amputees, all the cool stuff is titanium, carbon fiber or other, more exotic materials. With carbon fiber “blades” all the rage, it’s easy to forget that simpler technologies still work, and could be made to work even better with the addition of some inexpensive electronics. The Economical Bionic Leg project is the result of that idea.

Project creators [PremJ20] and [G.Vignesh] aren’t kidding about bringing the cost of these bionic legs down. The target goal is $60 per, with stainless steel and silicon rubber as a cheaper alternative to carbon fiber — the rubber would be molded to fit the amputated region. The heart of the project is a Particle Photon development board, with a flex sensor and accelerometer monitoring the prosthesis and supplying data to the cloud. It’s essentially a basic prosthetic leg with a monitoring system built in. Placing a sensor cuff on the regular leg, the artificial limb’s flexibility can be fine-tuned to match the two.

Will this inexpensive bionic leg ever compete in the Olympics, like [Oscar Pistorious] run in the 2012 London event? Probably not — the tech that goes into artificial limbs has the same amount of material science going into it as F1 racing and turbojet design. Still, this is a very cheap way to bring tech into something that desperately needs to be cheaper, and it’s a great Hackaday Prize entry, to boot.

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Retrotechtacular: Hacking Wartime Mail

October 6, 2017 by 33 Comments

I’m guessing you got quite a few e-mails today. But have you ever had a v-mail? That sounds like some new term for video e-mail, but it actually dates back to World War II. If you are in Europe, the term was Airgraph — not much more descriptive.

If you make a study of war, you’ll find one thing. Over the long term, the winning side is almost always the side that can keep their troops supplied. Many historians think World War II was not won by weapons but won by manufacturing capability. That might not be totally true, but supplies are critical to a combat force. Other factors like tactics, doctrine, training, and sheer will come into play as well.

On the other hand, morale on the front line and the home front is important, too. Few things boost morale as much as a positive letter from home. But there’s a problem.

While today’s warfighter might have access to a variety of options to communicate with those back home, in World War II, communications typically meant written letters. The problem is ships going from the United States to Europe needed to be full of materials and soldiers, not mailbags. With almost two million U.S. soldiers in the European Theater of Operations, handling mail from home was a major concern.

British Mail Hack

The British already figured out the mail problem in the 1930s. Eastman Kodak and Imperial Airways (which would later become British Airways) developed the Airgraph system to save weight on mail-carrying aircraft.  Airgraph allowed people to write soldiers on a special form. The form was microfilmed and sent to the field. On the receiving end, the microfilm was printed and delivered as regular mail.

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