[Fran]’s LEDs, Nixies, And VFDs.

January 4, 2014 by 21 Comments

FRAN LED

With a love of blinky and glowey things, [Fran] has collected a lot of electronic display devices over the years. Now she’s doing a few teardowns and tutorials on some of her (and our) favorite parts: LEDs and VFD and Nixie tubes

Perhaps it’s unsurprising that someone with hardware from a Saturn V flight computer also has a whole lot of vintage components, but we’re just surprised at how complete [Fran]’s collection is. She has one of the very first commercial LEDs ever made. It’s a very tiny red LED made by Monsanto (yes, that company) packaged in a very odd lead-and-cup package.

Also in her LED collection is a strange Western Electric part that’s green, but not the green you expect from an LED. This LED is more of an emerald color – not this color, but more like the green you get with a CMYK process. It would be really cool to see one of these put in a package with red, green, and blue LED, and could have some interesting applications considering the color space of an RGB LED.

Apart from her LEDs, [Fran] also has a huge collection of VFD and Nixie tubes. Despite the beliefs of eBay sellers, these two technologies are not the same: VFDs are true vacuum tubes with a phosphorescent coating and work something like a CRT turned inside out. Nixies, on the other hand, are filled with a gas (usually neon) that turns to plasma when current flows through one of the digits. [Fran] has a ton of VFDs and Nixies – mostly military surplus – and sent a few over to [Dave Jones] for him to fool around with.

It’s all very cool stuff and a great lead-in to what we hear [Fran] will be looking at next: electroluminescent displays found in the Apollo Guidance Computer.

Videos below.

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Recliner Sofa Given The Power Of The Pi

January 4, 2014 by 20 Comments

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If you go to buy a sofa these days you’ll not only be greeted with the option of one or more reclining positions, but a fully modern unit comes with motorized reclining. That simply wasn’t convenient enough for [Nicki] and [Kevin] who wanted to control the feature from a smartphone rather than a physical interface (buttons) on the side of the furniture. What resulted is the PiSofa, a Raspberry Pi connected to the furniture’s electronics with the help of a relay board.

This is most certainly a hack, but no doubt one with a lot of finesse. Check out that white PCB. That’s right, it’s a factory spun board to keep things nice and neat. They went with one of our favorite tricks by housing everything inside of a food storage container. After some Ruby coding the Pi now has complete control of the sofa. We’re not overstating this. It literally is the only way to control it because the original buttons no longer work. But that’s okay, turns out not only does it work with their smartphones, but with a [Kevin’s] Pebble watch as well.

We can’t think of any past hacks that specifically targeted the couch. But here’s a hammock that you can drive down the street.

Building A Raspberry PI Digital Photo Frame

January 4, 2014 by 3 Comments

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Digital photo frames aren’t very interesting on their own these days, but building one with a Raspberry Pi and strapping it with a bunch of useful features just might motivate you to check out this tutorial on building a ‘living’ digital photo frame.

This is [Samuel’s] first project with the Raspberry Pi, so he decided to build a digital photo frame that has the ability to download random pictures from his Flicker account and display them in a slideshow format. With all that extra IO on the Raspi, it was easy to incorporate a status LED and PIR sensor. When motion is detected by the PIR sensor, the photo frame is enabled; after 60 seconds of no movement, the photo frame is disabled by turning off the monitor port.

We love finding detailed write-ups like this because there is so much useful information in here like using the Flicker API, GPIO control, image handling, how to configure scripts to run on boot-up, and even some great troubleshooting code.  If you’d rather ditch the Raspi altogether and take things down a few levels, check out this PIC based 100% DIY digital picture frame.

Arcade Briefcase (the Briefcade)

January 3, 2014 by 8 Comments

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[Travis Reynolds] is part of an arcade club at work — the only problem? He’s the only one with an arcade machine, so they always end up at his place. So he decided to make his own portable, arcade briefcase to take to the office.

It all started with a quick trip to Goodwill where he found a beautiful maroon briefcase from the 80’s, for only $5! He then took apart a spare LCD monitor he had sitting around, and it worked incredibly well in his favor. He was able to reuse the LCD’s internal mounting brackets to secure it to the briefcase, and the video cables were just long enough to reach the Raspberry Pi.

The next problem he faced was the joystick height. He picked a Sanwa style joystick which is fairly small, but even that was too tall for the briefcase. So unfortunately, he needs to remove the ball of the joystick before closing the case. After testing out the proposed button layout, he cut a plywood mounting plate to hold everything in place. A bit of black spray paint later plus a power connector through the side of the case, and it’s complete!

He’s running Shea Silverman’s PiMame, which has an easy to use menu, quick setup, and great support. It’s an awesome project, and very well documented in case you’re itching to do something similar — I know we are!

Of course, if you have the space, a coffee table arcade machine is pretty sweet too…

[Thanks Brendan!]

Key Cutting With A CNC Mill

January 3, 2014 by 24 Comments

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Keys cost like what, $2 to copy at a locksmith? But where’s the fun in that? Here’s an easy way to cut your own keys using a CNC mill!

[Bolsterman] now “works” for a real estate company that rents out various properties. Whenever someone moves out, the locks need to be changed ASAP. They use Schlage locks, which can be re-keyed to any pin combination. New keys are typically cut with a punch or a key cutting machine — he actually had one years ago, but got rid of it. Not wanting to buy a new one for his new job at the real estate company, he decided to see how hard it would be to turn his small desktop CNC into his own personal key cutting machine.

All it took for [Bolsterman] to turn his mill into a key cutting machine was a 3/8th 90° countersink bit with the end ground to a flat approximately 0.055″ across (0.035″ is the width of a factory key, but a bit of leeway makes it easier to make the key). Then you simply zero the mill off of the shoulder of the key, and using the handy Schlage pin chart (included in the original link), cut the grooves!

To automate all of this, [Torrie Fischer] created a python script for generating the GCode  for keys based on [Bolsterman’s] technique — it’s hosted over at Noisebridge’s Wiki — check it out!

But if all that seems like too much effort, you could just print a new key instead…

PhotoTransistor Based Eye-Tracking

January 3, 2014 by 11 Comments

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The applications of eye-tracking devices are endless, which is why we always get excited to see new techniques in measuring the absolute position of the human eye. Cornell students [Michael and John] took on an interesting approach for their final project and designed a phototransistor based eye-tracking system.

We can definitely see the potential of this project, but for their first prototype, the system relies on both eye-tracking and head movement to fully control a mouse pointer. An end-product design was in mind, so the system consists of both a pair of custom 3D printed glasses and a wireless receiver; thus avoiding the need to be tethered to the computer under control . The horizontal position of the mouse pointer is controlled via the infrared eye tracking mechanism, consisting of an Infrared LED positioned above the eye and two phototransistors located on each side of the eye. The measured analog data from the phototransistors determine the eye’s horizontal position. The vertical movement of the mouse pointer is controlled with the help of a 3-axis gyroscope mounted to the glasses. The effectiveness of a simple infrared LED/phototransistor to detect eye movement is impressive, because similar projects we’ve seen have been camera based. We understand how final project deadlines can be, so we hope [Michael and John] continue past the deadline with this one. It would be great to see if the absolute position (horizontal and vertical) of the eye can be tracked entirely with the phototransistor technique.

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Build An Audio Spectrum Analyzer The Analog Way

January 3, 2014 by 18 Comments

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[Ryan] wanted a spectrum analyzer for his audio equipment. Rather than grab a micro, he did it the analog way. [Ryan] designed  a 10 band audio spectrum analyzer. This means that he needs 10 band-pass filters. As the name implies, a band-pass filter will only allow signals with frequency of a selected band to pass. Signals with frequency above or below the filter’s passband will be attenuated. The band-pass itself is constructed from a high pass and a low pass filter. [Ryan] used simple resistor capacitor (RC) filters to implement his design.

All those discrete components would quickly attenuate [Ryan’s] input signal, so each stage uses two op-amps. The first stage is a buffer for each band. The second op-amp, located after the band-pass filters, is configured as a non-inverting amplifier. These amplifiers boost the individual band signals before they leave the board. [Ryan] even added an “energy filler” mode. In normal mode, the analyzer’s output will exactly follow the input signal. In “energy filler” (AKA peak detect) mode, the output will display the signal peaks,  with a slow decay down to the input signal. The energy filler mode is created by using an n-channel FET to store charge in an electrolytic capacitor.

Have we mentioned that for 10 bands, all this circuitry had to be built 10 times? Not to mention input buffering circuitry. With all this done, [Ryan] still has to build the output portion of the analyzer: 160 blue LEDs and their associated drive circuitry. Going “all analog” may seem crazy in this day and age of high-speed micro controllers and FFTs, but the simple fact is that these circuits work, and work well. The only thing to fear is perf board solder shorts. We think debugging those is half the fun.