Push-Button Degaussing For An Arcade CRT

[Ed] was tasked with adding push-button degaussing to an arcade cabinet’s CRT console. The display can be rotated to portrait mode for games that require it, but each time this is done, the magnetic fields get out of whack.

Fortunately, the schematics arrived with the display. [Ed] found that the degauss coil is connected in series with a PTC fuse in an odd arrangement that he didn’t agree with. He decided to use an SSR to switch the coil, and after making lots of transistor-based designs on paper, grabbed a nearby Arduino.

[Ed] took off the PTC and soldered in two wires to its pads for the SSR. He added a wire to the power supply decoupling cap to power the new deguassing circuit and connected the SSR to the Arduino as an open collector input. There was just enough space available to mount the relay to the frame’s base and the Arduino on the side. [Ed] wrote a short method to trigger the SSR and reconnected the PTC fuse. Now it degausses at power up as well as on demand.

43oh.com Wasn’t Next To The Texas Instruments Booth

In addition to all the cool boards and booster packs found at Texas Instruments’ booth at Maker Faire, the folks from 43oh.com made a showing, but not next to the TI booth. In fairness, the TI booth was right across from NASA. 43oh is cool, but not NASA cool.

[Eric], known on the 43oh forums as [spirilis] showed off a few of the neat bits and bobs developed on the forums including a lightning detector, a VFD clock, a robot, and a whole lot of blinky things. There was an astonishing array of projects and boards at the booth, covering everything from OLEDs to motor drivers.

43oh is an interesting community centered around TI’s microcontrollers, like the AVRfreaks forum built around Atmel’s offerings. 43oh has a very active forum, IRC, and a store featuring projects made by members. It was great to see these guys at the faire, and we wish more of the homespun unofficial communities would make more of a showing at cons in the future.

Sorry about the mic cutting out in the video above. There was a sea of spewing RF near the booth. If anyone has advice for a *digital* wireless mic setup, we’re all ears. This is the current rig.

Making An Inductor Saturation Current Tester

[Kalle] tipped us about a quick project he made over a couple of evenings: an inductor saturation current tester. All the components used for it were salvaged from a beefy telecom power supply, which allows the tester to run currents up to 100A during 30us in the inductors to be characterized.

Knowing the limits of an inductor is very convenient when designing Switch Mode Power Supplies (SMPS) as an inadequate choice may result in very poor performances under high loads. [Kalle]’s tester simply consists in a N-Mosfet switching power through a load while a shunt allows current measurements. The saturation point is then found when the current going through the inductor suddenly peaks. As you can see from the picture above, 16 4700uF electrolytic caps are used to compensate for the sudden voltage drop when the Mosfet is activated. A video of the system in action is embedded after the break.

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Bluetooth Thingies At Maker Faire

In case you haven’t noticed, one of the more popular themes for new dev boards is Bluetooth. Slap a Bluetooth 4.0 module on a board, and you really have something: just about every phone out there has it, and the Low Energy label is great for battery-powered Internets of Things.

Most of these boards fall a little short. It’s one thing to throw a Bluetooth module on a board, but building the software to interact with this board is another matter entirely. Revealing Hour Creations is bucking that trend with their Tah board. Basically, it’s your standard Arduino compatible board with a btle module. What they’ve done is add the software for iOS and Android that makes building stuff easy.

Putting Bluetooth on a single board is one thing, but how about putting Bluetooth on everything. SAM Labs showed off their system of things at Maker Faire with LEDs, buttons, fans, motors, sensors, and just about every electrical component you can imagine.

All of these little boards come with a Bluetooth module and a battery. The software for the system is a graphical interface that allows you to draw virtual wires between everything. Connect a button to a LED in the software, and the LED will light up when the button is pressed. Move your mouse around the computer, and the button will turn on a motor when it’s pressed.

There are a few APIs that also come packaged into the programming environment – at the booth, you could open a fridge (filled with cool drinks that didn’t cost five dollars, a surprise for the faire) and it would post a tweet.

Retrotechtacular: The Diesel Story

The diesel engine was, like many things, born of necessity. The main engine types of the day—hot bulb oil, steam, coal gas, and gasoline—were not so thermally efficient or ideal for doing heavy-duty work like driving large-scale electrical generators.  But how did the diesel engine come about? Settle in and watch the 1952 documentary “The Diesel Story“, produced by Shell Oil.

The diesel engine is founded on the principle of internal combustion. Throughout the Industrial Age, technology was developing at breakneck pace. While steam power was a great boon to many burgeoning industries, engineers wanted to get away from using boilers. The atmospheric gas engine fit the bill, but it simply wasn’t powerful enough to replace the steam engine.

hot bulb oil engineBy 1877, [Nikolaus Otto] had completed work on his coal gas engine built on four-stroke theory. This was the first really useful internal combustion engine and the precursor of modern four-stroke engines. It was eventually adapted for transportation with gasoline fuel. In 1890, the hot bulb oil engine was developed under the name Hornsby-Akroyd and primarily used in stationary power plants. Their flywheels had to be started manually, but once the engine was going, the bulb that drove combustion required no further heating.

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A Folding Laser Cutter

Want a laser cutter, but don’t have the space for one? How about a portable machine to engrave and cut wood and plastics? A folding laser cutter solves these problems, and that’s exactly what Red Ant Lasers was showing off last weekend at Maker Faire.

Inside the team’s Origami laser cutter is a 40 Watt CO2 tube, shooting its beam along an entirely enclosed beam path. The beam travels through the body of the machine, out into the folding arm of the machine, and down to whatever material you’ve placed the Origami on. It’s a 40 Watt laser so it will cut plywood and plastics, and as shown in the video above, does a fine job at engraving plywood.

This is a Class 4 laser device operating without any safety glass, but from the short time I spent with the Red Ant team, this is a reasonably safe device. You will need safety glasses if you’re within five feet, but after that, everything (according to OSHA, I think) is safe and not dangerous. Either way, it’s a tool just like a table saw. You don’t see commentors on the Internet complaining about how a spinning metal blade is dangerous all the time, do you?

The Red Ant guys are currently running a Kickstarter for their project, with a complete unit going for $4200. It’s pricier than a lot of other lasers, but not being constrained by the size of a laser cutters enclosure does open up a few interesting possibilities. You could conceivably cut a 4×8 sheet of plywood with this thing, and exceptionally large engravings start looking easy when you have a portable laser cutter.

THP Semifinalist: Honeybee Hive Monitoring

[Ken] keeps his bees remotely and can’t check on them as often as he might like to. He wanted some way of knowing when they were out of space, because that slows down their nectar collection. He knew he could do this by remotely tracking the weight and internal temperature of the hives.

His first prototype revolved around a postal scale that couldn’t be turned off between readings. This meant that he needed a bigger solar panel and battery than originally intended. For about a week, the hives were sending data to Thingspeak through an Arduino Fio over XBee.

The current iteration measures the load cells with an HX711 24-bit ADC. This sends the scale data to an Apitronics Bee unit, which adds in temperature data from the hives and sends everything to an Apitronics Hive. [Ken] will also stream it to a cloud service so he can monitor them in real-time. [Ken] wants to see as much data as possible and contribute to NASA’s HoneyBeeNet program, so he has a second Bee unit set up to handle a nearby Apitronics weather station.

SpaceWrencherThe project featured in this post is a semifinalist in The Hackaday Prize.