Building A CO2 Laser In A Hardware Store


Over on the Projects site, [ThunderSqueak] is pushing the bounds of what anyone would call reasonable and is building a CO2 laser from parts that can be found in any home improvement store.

Despite being able to cut wood, paper, and a bunch of other everyday materials, a carbon dioxide laser is actually surprisingly simple. All you need to do is fill a tube with CO2, put some mirrors and lenses on each end, and run an electric current through the gas. In practice, though, there’s a lot of extra bits and bobs required for a working laser.

[ThunderSqueak] will need some sort of cooling for his laser, and for that he’s constructed a watercooling jacket out of 2″ PVC. In the end caps, a pair of brass pipe fittings are JB Welded in place, allowing a place for the mirror assembly and lenses.

The mirror mounts are the key component of this build, but the construction method is surprisingly simple. [ThunderSqueak] is using a few brass barbed hose fittings, with washers stuck on one end. The washers are drilled to accept a trio of bolts that will allow the mirrors to be perfectly parallel; anything less and the CO2 won’t lase.

The build isn’t complete yet, but having already built a few lasers, there’s little doubt [ThunderSqueak] will be able to pull this one off as well.


Measuring The Lifespan Of Nixie Tubes


Nixie tubes have two things going for them: they’re awesome, and they’re out of production. If you’re building a clock – by far the most popular Nixie application, you’re probably wondering what the lifespan of these tubes are. Datasheets from the manufacturers sometimes claim a lifetime as low as 1000 hours, or a month and a half if you’re using a tube for a clock. Obviously some experimentation is in order to determine the true lifetime of these tubes.

Finding an empirical value for the lifetime of Nixies means setting up an experiment and waiting a very, very long time. Luckily, the folks over at SALTechips already have a year’s worth of data.

Their experimental setup consists of an IN-13 bargraph display driven with a constant current sink. The light given off by this Nixie goes to a precision photometer to log the visual output. Logging takes place once a week, and the experiment has been running for 57 weeks so far.

All the data from this experiment is available on the project page, along with a video stream of the time elapsed and current voltage. So far, there’s nothing to report yet, but we suppose that’s a good thing.

Retrotechtacular: First laser transmitter built 50 years ago


Most of the time we feature hokey film footage in our Retrotechtacular series, but we think this hack is as cool today as it was fifty years ago. [Clint] wrote in to tell us about Operation Red Line. It was an experiment performed May 3rd and 4th, 1963, which means the 50th anniversary just passed a few weeks ago. The hack involved sending data (audio in this case) over long distances using a laser. But back then you couldn’t just jump on eBay and order up the parts. The team had to hack together everything for themselves.

They built their own helium-neon laser tube, which is shown on the right. The gentlemen involved were engineers at a company called Electro-Optical System (EOS) by day, and Ham radio enthusiasts by night. With the blessing of their employer they were able to ply their hobby skills using the glass blowing and optical resources from their work to get the laser up and running. With that side of things taken care of they turned to the receiving end. Using a telescope and a photomultipler they were able to pick up the beam of light at a distance of about 119 miles. The pinnacle of their achievement was modulating audio on the transmitter, and demodulating it with the receiver.

[Clint] knows the guys who did this and wrote up a look back at the project on his own blog.

A clock made out of some very weird tubes

If you’re like [Richard], you’ve got a few really rare components lying around. Maybe it’s a very weird micro or a really tiny CRT, but eventually you’ve got to build something with these parts. When [Richard] decided to put some ITS1A neon display tubes to use, he fell back to the old standby – a really awesome clock.

Unlike the lowly Nixie tube, the ITS1A tube is weird. It’s a neon seven-segment display that can be controlled directly from the pins of a microcontroller. It does this with the help of seven tiny thyratrons in each segment. Even though this tube has neon, the display isn’t the familiar neon orange-red. The tube emits a lovely green with the help of a phosphor coating.

With a single digit already incorporated into [Richard]‘s clock, he needed four indicators for the hours and minutes. After a failed experiment with a crazy 4-color, 16-pixel Melz ITM2-M display, he moved on to a simpler MTX90 thyratron indicator.

Using the same control scheme as his earlier numitron clock, Richard had a PCB made and wired everything up. The seven-segment tube indicates the value, and the indicator tubes indicates the position of the digit in the XX:XX standard. A very cool  build with parts you don’t see coming around often.

Neon binary clock

[Josiah] said ‘no’ to LEDs and instead used blue-phosphor neon lamps to build this binary clock. The ATmega328 inside uses three 8-bit shift registers to control the display. Each lamp needs a high-voltage NPN transistor in order to switch on the 150V necessary for proper illumination. A simple circuit was used to pull a 60 Hz clock signal out of the incoming 16VAC power. Unfortunately it was a bit too simple and didn’t provide a clean signal. [Josiah's] workaround is something of a debounce subroutine in the firmware to prevent multiple interrupts on the falling edge.

The last project we saw from [Josiah] was the Coachella Lamp. That was a show piece of antiquated technology and this is another show piece with a minimalistic style. We also liked seeing the protoboard work on the inside. That’s a pretty jam-packed circuit board and keeping everything in the right place while you build up each trace with blobs of solder is no small feat.

A bright way to cycle

Want to be visible when cycling at night? [Neon Dean] came up with this possible solution, which he cruised on at Nuit Blanche. Its a bicycle with neon lights mounted on every surface possible. [Dean], who gave a similar treatment to his car, explained how it worked. All of the tubes take their power from a 12VDC battery he carries in a fanny pack. 12V is a far too low voltage to power the tubes, so a step up transformer is used to bring that number way up. [Dean] also decided to install a neon tube on each wheel. In order to deliver power to them, he mounted a rotor on each wheel, with two conductive tracks running close to the edge of each rotor. Two strips of steel act as brushes (in a manner similar to those on slot cars), and deliver the stepped-up power to the tubes. One creative, but perhaps not so bright, idea is [Dean]‘s neon tube helmet.

NeonDeanBrushes12Vfanny transformer copy

Toronto embraces 4-letter words

This year was not the first in which the City Hall of Toronto was lit up in a unique way. However, it was the first time that the government building was used to project 4-letter words. Brainchild of [D.A. Therrien], the 4LWM represents something that he imagined for a long time. [Therrien] built the huge sign in Scottsdale, Arizona, where he displayed it over the waterfront. He was later commisioned to bring the sign to Toronto for Nuit Blanche after making some adaptations (due to weather differences). The sign is composed of 4 huge 16-segment displays. Each segment is made of many neon light modules. This configuration makes it less noticable if one such module fails. The sign is controlled below from a computer, which allows it to display text and simple animations. It’s the first in a series of installations dubbed “Beautiful Light” by [Therrien]. Despite the name, no inappropriate language was displayed on the sign.