There’s been a resurgence of interest in vacuum tubes. Even if you do think audio sounds better through a tube, you have to admit the care and feeding of filaments and plate voltages isn’t trivial. [Ed Nisley] decided to sidestep all that and just build an objet d’art that looks like a tube.
A burned out halogen bulb stands in for the tube, and a ceramic base holds the bulb. It also conceals–what else–an Arduino. The Arduino drives a knock-off Neopixel LED hidden in a faux plate cap. The result is a glass envelope bathed in a cold blue and purple glow that changes under software control.
We’d really like to see this kind of tube inside some rebuilt piece of tube gear. Or maybe Korg should offer LED lighting options for their recent tube in a chip form factor. If you really want to be a top-tier tube hacker, you can always try your hand at repair.
The triode is one of the simplest kinds of vacuum tubes. Inside its evacuated glass envelope, the triode really is just a few bits of wire and metal. Triodes are able to amplify signals simply by heating a cathode, and modulating the flow of electrons to the anode with a control grid. Triodes, and their semiconductor cousin the transistor, are the basis of everything we do with electricity.
Because triodes are so fantastically simple, they’re the parts most commonly crafted by the homebrew tube artisans of today. You don’t need a glass blowing lathe to make the most basic vacuum tube, though: [Marcel] built one from the light bulb used in a car’s tail light.
The light bulb in your car’s tail light has two filaments inside: one for the normal tail light, and a second one that comes on when you brake. By burning out the dimmer filament, [Marcel] created the simplest vacuum tube device possible. In his first experiment, he turned this broken light bulb into a diode by using the disconnected filament as the anode, and the burning filament as the cathode. [Marcel] attached a 1M resistor and measured 30mV across it. It was a diode, with 30μA flowing.
The triode is just a diode with a grid, but [Marcel] couldn’t open up the light bulb to install a piece of metal. Instead, he wrapped the bulb in aluminum foil. After many attempts, [Marcel] eventually got some amplification out of his light bulb triode.
The performance is terrible – this light bulb triode actually has an “amplification” of -108dB, making it a complete waste of energy and time. It does demonstrate the concept though, even though the grid isn’t between the anode and cathode, and this light bulb is probably filled with argon. It does work in the most perverse sense of the word, and makes for a very interesting build.
With everything that’s been happening in the news lately, [Jarek] decided it was finally time to finish up his latest project. The Internet of Things has been exploding with projects lately, and this clock that also alerts him of the weather is the latest addition. Plus it has the added bonus of using everybody’s favorite display: nixie tubes!
Of course, using high voltage for the nixies can be terror-inducing, but [Jarek] found a power supply on eBay that was able to power the tubes for not too much money. The controller is an HV5622 which can control up to 32 nixies while only using up three pins on a microcontroller which is pretty handy if you have a limited number of output pins.
The clock also has another device hidden behind all of the wires for the tubes: an ESP8266 to give it network connectivity. The clock connects to the Internet and searches for the nine-hour weather forecast. There are a few nixie lights behind the display which illuminate cutouts in the case to indicate a few different weather statuses. It’s a very polished project, and since it’s enclosed in a nice case it’s not likely to be mistaken for any movie props. Of course, other nixie projects don’t have the same comforting look.
Continue reading “Nixie Tube Clock Isn’t Just a Clock”
[Sprite_tm], like most of us, is fascinated with the earlier ways of counting and controlling electrons. At a hacker convention, he found an old Dekatron tube hooked up to a simple spinner circuit. The prescription for this neon infatuation was to build something with a Dekatron, but making another spinner circuit would be a shame. Instead, he decided to do something useful and ended up building an Internet Speedometer with this vintage display tube.
Like all antique tubes, the Dekatron requires about 400V to glow. After a bit of Googling, [Sprite] found a project that drives a Dekatron with an AVR with the help of a boost converter. Borrowing the idea of controlling a boost converter with a microcontroller, [Sprite] built a circuit with the Internet’s favorite Internet of Things thing – the ESP8266 – that requires only a 12 volt wall wart and a handful of parts.
Controlling the rotating glow of a Dekatron is only half of the build; this device is an Internet speedometer, too. To read out his Internet speed, [Sprite] is using a managed switch that allows SNMP to read the number of incoming and outgoing octets on a network interface. By writing a simple SNMP client for the ESP8266, the device can read how clogged the Intertubes are, both incoming and outgoing.
With an acrylic case fresh out of the laser cutter and a remarkably good job at bending acrylic with a heat gun, [Sprite] has a tiny device that tells him how much Internet he’s currently using. He has a video of it running a speedtest, you can check that video out below.
Continue reading “An Internet Speedometer With A Dekatron”
We’ve been admirers of the work [Eric] and friends have been doing over at TubeTime for years. One of the earliest we can remember is the decatron kitchen timer, and we still tell the story of [Eric] purposely leaving out button debouncing in order to make his vector flappy bird even harder.
TubeTime is back at it this year and we had the opportunity to speak with them at Bay Area Maker Faire. The group specializes in working with old tube displays and this year’s offering was spectacular in many ways. First off, the software side of things is an emulator running on an STM32 F4 Discovery board. The chips on these boards have a pair of 12-bit DACs which are driving the X and Y of the vector displays. Code to run the original ROMs was ported from existing projects, but the audio for the games was kind of a hack to get working.
This particular display is where things get really fascinating. The tube itself was originally manufactured as test equipment for television repairmen. What’s fascinating about this is that [Eric] had to rewind the deflection yokes himself to get it working again. Luckily he documented quite a bit about his initial research into this process and his experiments to remedy some distortion issues he encountered once it was working.
Make sure to head on over to TubeTime and read their overview of the Battlezone machine. After the break we’ve also embedded a few of our own pictures as well as the interview at BAMF.
Continue reading “Battlezone Played on Vector Display with Hand-Wound Yoke”
The tubes you’ll find in guitar amps and high-end stereos were first designed in the 30s and 40s, and when you get to really, really advanced tube technology you’d be looking at extremely small tubes made in the 70s for military applications. For 40 years, there really haven’t been many advances in tube technology. Now, at last, there’s something new.
The Nutube 6P1, as this curious invention is called, is a full triode or half of a 12ax7 you’ll find in just about every tube amp ever. Unlike the 12ax7, it consumes 2% of the power required of a normal tube, is 30% of the size of the normal tube, and lasts for 30,000 hours.
This new tube-chip thing was brought to life by Korg, makers of fine musical equipment and Noritake Co., manufacturers of vacuum fluorescent displays. There’s no word on what these tubes will be used in and there’s no data sheet. There will be further announcements this year, so don your speculation spectacles and head to the comments.
[Eric] has an Atwater Kent 55C AM radio from the early 1900’s. He’s been trying to restore the radio to proper working condition. His most recent pain has been with the rectifier tube. The tube is supposed to have a complete vacuum inside, but that’s not the case here. When the tube is powered up, it glows a beautiful violet color. It may look pretty, but that’s indicative that gas has leaked into the tube. It needed to be replaced.
[Eric] had a tube that would serve as a good replacement, but it’s plug didn’t fit the socket properly. He was going to have to use this old broken tube to make an adapter. Rather than just tearing the old tube apart, he decided to have some fun with it first. He hooked it up to a variac, an ammeter, and a volt meter. Then he slowly increased the voltage to see what would happen. The result was visually stunning.
The tube starts out with the same violet/blue glowing [Eric] experienced previously. As the voltage increases, it gets more and more intense. Eventually we start to see some green colors mixing in with the violets. [Eric’s] reaction to this unexpected result is priceless. As the tube gets increasingly hot, the anode starts glowing an orange-red color. Finally, the filament starts to crackle like a sparkler before the tube just gives up and completely fails.
After the light show, [Eric] moves on to replacing the tube. He begins by tapping on the old tube’s socket with the end of a screwdriver. After much tapping, the glass starts to come lose from the socket. After a bit of wiggling and twisting the tube finally came free from the socket. [Eric] luckily had an unused octal socket that fit perfectly inside of the old socket. All he needed to do to build his adapter was to connect the four pins from the old adapter to the proper pins on the octal socket. Piece of cake.
…Or so [Eric] thought. After testing some new tubes with a tube tester, he realized he had soldered all four pins incorrectly. On top of that, he had super glued the adapter together. He eventually got the two pieces apart. This time he removed all of the unused pins from the octal socket so he wouldn’t get it wrong. Another run on the tube tester confirmed that everything looked good. After plugging the tube into the radio, it worked just as expected
If you need fabrication rather than repair, we’ve got you covered there as well. Check out [Charles Alexanian’s] process for making new vacuum tubes in his garage. Now if you just have too darn many of them around, you can always decorate your pad with ’em.
Continue reading “Vacuum Tube Repair After a Spectacular Failure”