Home Brew Vacuum Tubes Are Easier Than You Think

It all began with a cheap Chinese rotary vane vacuum pump and a desire to learn the witchcraft of DIY vacuum tubes. It ended with a string of successes – a working vacuum chamber, light bulbs, glow tubes, diodes, and eventually this homebrew power triode and the audio amplifier built around it.

[Simplifier]’s workshop seems like a pretty cool place. It must have a bit of an early 20th-century vibe, like the shop that [John Fleming] used for his early work on vacuum tubes. Glass work, metal work, electronics – looks like [Simplifier] has a little bit of everything going on. True to his handle, once [Simplifier] had a cheap but effective vacuum rig he started with the easiest projects – incandescent and gas discharge lamps. Satisfied that he could make solid electrical and physical connections and evacuate the tubes, he moved on to diodes and eventually triodes. The quality of the tubes is pretty impressive – stray gasses are removed with a bake-out oven and induction-heated titanium getters. And the performance is pretty solid, as the video below reveals.

Very impressive overall, and it’s not just the fact that he’s building tubes from scratch – we’ve seen that before. What shines here is that specialized equipment is not needed to make working and reliable tubes – just a MAPP torch, simple hand tools, and a low-end vacuum rig. Anybody could – and probably should – give this a try.

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An Open Source Lead Tester

If you’ve ever needed an example of colossal failure of government actors, you need only to look at Flint, Michigan’s water crisis. After the city of Flint changed water supplies from Detroit to the Flint river, city officials failed to add the correct corrosion inhibitors. This meant that lead dissolved into the water, thousands of children were exposed to lead in drinking water, a government coverup ensued, [Erin Brockovich] showed up, the foreman of the Flint water plant was found dead, and the City Hall office containing the water records was broken into.

Perhaps inspired by Flint, [Matthew] is working on an Open Source Lead Tester for his entry into the 2016 Hackaday Prize.

[Matthew]’s lead tester doesn’t test the water directly. Instead, it uses a photodiode and RGB LED to look at the color of a lead test strip. These results are recorded, and with a bit of a software backend, an entire city can be mapped for lead contamination in a few days with just a few of these devices.

One problem [Matthew] has run into is the fact the Pi does not have analog to digital conversion, making reading a photodiode a little harder than just plugging a single part into a pin header and watching an analog value rise and fall. That really shouldn’t be a problem – ADCs are cheap, especially if you only need a single channel of analog input with low resolution. [Matthew] is also looking into using the Pi webcam for measuring the lead test strip. There are a lot of decisions to make, but any functional device that comes out of this project will be very useful in normal, functioning governments. And hopefully in Flint, Michigan too.

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Soldering Iron Cauterization

Medical hacks are not for the weak of stomach, so read further at your own risk. [Todd Harrison] shows you how to remove a stubborn skin wart using a good ol’ soldering iron, and a fair endurance for pain. After all, cauterization is a well known and documented medical procedure. If you have the stomach for this, read on, or better, check out his 9 minute video after the break. If there are kids around, turn down the volume between 1:40 to 2:20.

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DNA Extraction With A 3D-Printed Centrifuge

[F.Lab] is really worried that we are going to prepare a DNA sample from saliva, dish soap, and rubbing alcohol in their 3D-printed centrifuge and then drink it like a shot. Perhaps they have learned from an horrific experience, perhaps biologists have different dietary requirements. Either way, their centrifuge is really cool. Just don’t drink the result. (Ed note: it’s the rubbing alcohol.)

The centrifuge was designed in Sketch-Up and then 3D printed. They note to take extra care to get high quality 3D prints so that the rotor isn’t out of balance. To get the high speeds needed for the extraction, they use a brushless motor from a quadcopter. This is combined with an Arduino and an ESC. There are full assembly instructions on Thingiverse.

[F.Lab] has some other DIY lab equipment designs, such as this magnetic stirrer. Which we assume you could use to make a shot if you wanted to. However, it’s probably not a good idea to mix lab supplies and food surfaces. Video after the break.

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Retrotechtacular: TV Troubleshooting

As technology advances, finding the culprit in a malfunctioning device has become somewhat more difficult. As an example, troubleshooting an AM radio is pretty straightforward. There are two basic strategies. First, you can inject a signal in until you can hear it. Then you work backwards to find the stage that is bad. The other way is to trace a signal using a signal tracer or an oscilloscope. When the signal is gone, you’ve found the bad stage. Of course, you still need to figure out what’s wrong with the stage, but that’s usually one or two transistors (or tubes) and a handful of components.

A common signal injector was often a square wave generator that would generate audio frequencies and radio frequency harmonics. It was common to inject at the volume control (easy to find) to determine if the problem was in the RF or audio sections first. If you heard a buzz, you worked backwards into the RF stages. No buzz indicated an audio section problem.

A signal tracer was nothing more than an audio amplifier with a diode demodulator. Starting at the volume control was still a good idea. If you heard radio stations through the signal tracer, the RF section was fine. Television knocked radio off of its pedestal as the primary form of information and entertainment in most households, and thus the TV repair industry was created.

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The Dark Arts: Anonymity

Love him or hate him, Edward Snowden knew a thing or two about anonymity. In June of 2013, he blew the whistle on the NSA’s out-of-control programs that can target virtually anyone plugged into the digital age. The former CIA employee was working as a contractor for the NSA, where he had access to highly classified documents for many of these general populace surveillance programs. He eventually took off to Hong Kong and released the documents to a handful of reporters. One of these documents was a power point presentation of the NSA complaining about how the TAILS operating system was a major thorn in their side. Naturally, Snowden insisted that the reporters and himself only communicate via the TAILS O/S. He used PGP, which is an encryption method with the highly sophisticated title of “Pretty Good Privacy”, and asked not to be quoted at length for fear of identification via stylometry.

In this article, we’re going to go over the basics of anonymity, and introduce you to methods of staying anonymous while online.

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Not Even Hamsters Are Safe From The Internet Of Things

The internet of things is this strange marketing buzzword that seems to escape from the aether and infect our toasters and refrigerators. Now even a hamster is not safe.

[Mifulapirus]’s hamster, Ham, was living a pleasant hamster life. Then his owner heard about another hamster named Sushi, whose running wheel stats were broadcasted to the internet. Not to be left behind, Ham’s wheel was soon upgraded. Now Ham is burdened by the same social pressures our exercise apps try to encourage us to use. No, we are most certainly not going to tell our friends about two fourteen minute miles with a twenty minute coffee break in the middle, MapMyRun, we are not.

The feat of techno enslavement for the little hamster was accomplished with a custom board, an esp8266, and an arduino as described in the instructable. The arduino can be left out of the project now that the libraries have been ported to the esp8266. A hall effect sensor detects when the 3D printed hamster wheel is spinning.

If you’d like to check in on Ham, the little guy is alive and well, and the twitter is here. It looks like it’s been upgraded since the original article was posted. Now it shows when Ham is awake and running around the cage doing hamster errands.