Push-Button Degaussing for an Arcade CRT

arcade degaussing control

[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.

Retrotechtacular: The Diesel Story

title cardThe 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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THP Semifinalist: Honeybee Hive Monitoring

hives[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.

Sweet Stepper of [Jeremy]‘s Rocks Out with its Box Out

Stepper motor MIDI music boxInspired by the floppy drive orchestras of others, [Jeremy] has built a Pi-driven MIDI music box with stepper motor resonators and outlined the build on hackaday.io.

Control for the motors comes from an Iteaduino Mega 2560. The music starts as a MIDI file, gets processed into a text file, and is played over serial by a Raspberry Pi. He’s added percussion using K’NEX instruments and 9g servos, which we think is a nice touch. It can be powered via LiPo or from the wall, and [Jeremy] baked in protection against blowing up the battery. As he explains in the tour video after the break, the box is clamped to a wooden table to provide richer sound.

[Jeremy]‘s favorite part of the build was enclosing the thing as it was his first time using panel-mount components. Stick around to see a walk-through of the guts and a second video demonstrating its musical prowess.

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Fail of the Week: Robotic 1950 Mercury Boogies, Won’t Come Back From Dead Man’s Curve

1950 Mercury[Dave] wanted to make an Arduino robot out of a remote-control 1950 Mercury. He removed the RC portion from the car and kept the drive and steering motors. The idea was to use three ultrasonic rangefinders in the grille real estate and move the car forward based on the longest distance detected.

He initially used a Seeed motor controller and some Grove cables soldered to his sensors to power the steering. It went forward, but only forward, and [Dave] decided the motor controller and the car’s steering motor weren’t playing well together.

[Dave] had the idea to use relays instead to both power the motor and determine polarity. Now, the Merc was turning and avoid obstacles about half the time, but it was also getting dinged up from hitting walls. He figured out that his sensor arrangement was making the car turn immediately and decided to give the program information from the wheels with a reed switch and a rare earth magnet. The only problem is that the caliber of magnet required to trip the reed switch is too heavy and strong. [Dave] and has concluded that he simply can’t exercise the kind of control over the car that he needs. and will build his own robot chassis.

Update: Check out a video of [Dave]‘s car after the break.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

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The First Annual Omaha Mini Maker Faire Was Definitely Something to Write Home About

tiny commemorative bookIf you ask me, Omaha’s first annual Mini Maker Faire was a rousing success. I think that the Faire’s coordinator, [Eric] of Omaha Maker Group would readily agree.The event was held at the Omaha Children’s Museum, an energetic and colorful backdrop for the 30 makers who were on hand to present their creations.

KITTThe representatives of the [Omaha Maker Group] had a total of three booths. One of them displayed the various fantastic things that have come out of their ‘space, which we will cover in an upcoming post. They brought the PiPhone that I told you about in my Kansas City Maker Faire post, and [Foamyguy] found a melodic easter egg hidden in the menu. [OMG] also brought their solar-powered EL wire logo sign, a quadcopter, a giant brushbot, a hexapod, a cigar box guitar, a really fun marble run, a steampunk Barbie, and KITT, their award-winning Power Racing Series car. And yeah, you bet it has a Larson scanner.

At their second booth, Fairegoers were constructing their own regular-size brushbots using 3D-printed chassis. These were specially designed to accommodate the toothbrush heads, pager motors, and CR2032s they brought to share. [Sarah] of [OMG] had her own popular booth and was showing off her costumes, clay creations, and jewelry.

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Retrotechtacular: The CURTA Mechanical Calculator

CURTA mechanical calculatorThe CURTA mechanical calculator literally saved its inventor’s life. [Curt Herzstark] had been working on the calculator in the 1930s until the Nazis forced him to focus on building other tools for the German army. He was taken by the Nazis in 1943 and ended up in Buchenwald concentration camp. There, he told the officers about his plans for the CURTA. They were impressed and interested enough to let him continue work on it so they could present it as a gift to the Führer.

This four-banger pepper mill can also perform square root calculation with some finessing. To add two numbers together, each must be entered on the digit setting sliders and sent to the result counter around the top by moving the crank clockwise for one full rotation. Subtraction is as easy as pulling out the crank until the red indicator appears. The CURTA performs subtraction using nine’s complement arithmetic. Multiplication and division are possible through successive additions and subtractions and use of the powers of ten carriage, which is the top knurled portion.

Operation of the CURTA is based on [Gottfried Leibniz]‘s stepped cylinder design. A cylinder with cogs of increasing lengths drives a toothed gear up and down a shaft. [Herzstark]‘s design interleaves a normal set of cogs for addition with a nine’s complement set. When the crank is pulled out to reveal the red subtraction indicator, the drum is switching between the two sets.

Several helper mechanisms are in place to enhance the interface. The user is prevented from ever turning the crank counter-clockwise. The crank mechanism provides tactile feedback at the end of each full rotation. There is also a lock that disallows switching between addition and subtraction while turning the crank—switching is only possible with the crank in the home position. There is a turns counter on the top which can be set to increment or decrement.

You may recall seeing Hackaday alum [Jeremy Cook]‘s 2012 post about the CURTA which we linked to. A great deal of information about the CURTA and a couple of different simulators are available at curta.org. Make the jump to see an in-depth demonstration of the inner workings of a CURTA Type I using the YACS CURTA simulator.

[Read more...]

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