Radio Receiver Or Art? Why Not Both?

September 15, 2015 by Al Williams 17 Comments

We’ve heard it said before that you should build things twice. Once to learn how to build it and the second time to build it right. [AA7EE] must agree. He was happy with his homebrew regenerative receiver that he called Sproutie. But he also wanted to build one more and use what he learned to make an even better receiver. The Sproutie Mark II was born.

This isn’t some rip off of an old P-Box kit either. [AA7EE] used a four-device RF stage with FET isolation back to the antenna and a regulated power supply. Plug in coils allow reception on multiple bands ranging from about 3 to 13 MHz. There’s an audio stage with multiple selectable audio filters, and–the best part–a National HRO tuning dial that is a work of art all by itself.

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Thermal Vision HUD Isn’t Only For Fighter-Jets!

September 15, 2015 by James Hobson 37 Comments

In case you weren’t aware, thermal vision units have seen huge price reductions lately. There’s a few on the market for under $300! While that might still seem expensive, remember, it’s thermal-freaking-vision. [Tim] bought a Seek Thermal as soon as it was available, and just recently finished his first project with it — giving his car a thermal HUD for driving at night.

The Seek Thermal is a small thermal imaging unit that has a micro USB attachment for phones. Simply plug it in, and your phone becomes the preview window. But for mounting on your car, you can’t have it behind a window, because most glass is not transparent to heat wavelengths, so [Tim] had to get creative.

He designed and 3D printed a magnetic mount for it to sit on the hood of his car. But in the case any debris from the road hit it, he wanted to protect the lens. So he started looking up thermally transparent materials — turns out they’re really expensive.

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How To Build A Pocket-Sized MBed Signal Generator

September 15, 2015 by Al Williams 13 Comments

Last month, I talked about how to get started with mBed and ARM processors using a very inexpensive development board. I wanted to revisit mBed, though, and show something with a little more substance. In particular, I often have a need for a simple and portable waveform generator. It doesn’t have to be too fancy or meet the same specs as some of the lab gear I have, but it should be easy to carry, power off USB, and work by itself when required.

My requirements mean I needed a slightly more capable board. In particular, I picked up a K64F board. This is very similar to the KL25Z board but has a bit more of everything–speed, memory, etc. What I really wanted, though, was the SD card slot. I did, however, do my early testing on a KL25Z, so if you have one, you can still work through the code, although standalone operation won’t be possible. The price jumps from $13 to $35, but you get a lot more capability for the price.

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Reverse Engineering An Obsolete Security System

September 15, 2015 by Brian Benchoff 32 Comments

[Veghead] recently went to a surplus warehouse filled with VHS editing studios, IBM keyboards, electronic paraphernalia from 40 years ago, and a lot of useless crap. His haul included a wooden keypad from an old alarm system that exuded 1980s futurism, and he figured it would be cool to hook this up to an alarm system from 2015. How did he do that? With software defined radio.

After pulling apart the alarm panel, [Veghead] found only a single-sided board with a 9V battery connector. There were no screw terminals for an alarm loop, meaning this entire system was wireless – an impressive achievement for the mid-80s hardware. A quick search of the FCC website showed this alarm panel was registered to two bands, 319MHz and 340MHz, well within the range of an RTL-SDR USB TV tuner dongle.

After capturing some of the raw data and playing it back in Audacity, [Veghead] found a simple OOK protocol that sends two identical binary patterns for each key. A simple program takes the raw bit patterns for each key press and codes them into a map for each of the twelve buttons.

Although the radio still works, [Veghead] found the waveforms captured by his RTL-SDR were an abomination to RF. All the components in this security system are more than 30 years old at this point, and surely some of the components must be out of spec by now. Still, [Veghead] was able to get the thing working again, a testament to the usefulness of a $20 USB TV tuner.

Thanks [Jose] for sending this one in

No User Serviceable Parts Inside? The Rise Of The Fix-It Culture

September 15, 2015 by Dan Maloney 90 Comments

pix-tv-repair-shop — [Source: 1950s Television]

My first job out of high school was in a TV shop. I was hired mainly for muscle; this was the early 1980s and we sold a lot of console TVs that always seemed to need to be delivered to the third floor of a walk up. But I also got to do repair work on TVs and stereos, and I loved it. Old TVs from the 60s and 70s would come in, with their pre-PCB construction and hand-wired chassis full of terminal strips and point to point wiring that must have been an absolute nightmare to manufacture. We’d replace dodgy caps, swap out tubes, clean the mechanical tuners, and sometimes put a new picture tube in – always the diagnosis that customers dreaded the most, like being told they’d need a heart transplant. We kept those old sets alive, and our customers felt like they were protecting their investment in their magnificent Admiral or Magnavox console with the genuine – and very, very heavy – walnut cabinet.

I managed to learn a lot from my time as a TV repairman, and I got the bug for keeping things working well past the point which a reasonable person would recognize as the time to go shopping for a new one. Fixing stuff is where I really shine, and my house is full of epic (in my mind, at least) repairs that have saved the family tens of thousands of dollars over the years. Dishwasher making a funny noise? I’ll just pull it out to take a look. You say there’s a little shimmy in the front end when you brake? Pull the car into the garage and we’ll yank the wheels off. There’s basically nothing I won’t at least try to fix, and more often than not, I succeed.

I assumed that my fix-it bug made me part of a dying breed of cheapskates and skinflints, but it appears that I was wrong. The fix-it movement seems to be pretty healthy right now, fueled in part by the explosion in information that’s available to anyone with basic internet skills.

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Mythical Game Boy Advance Colors Hacked Into Reality

September 15, 2015 by Brian Benchoff 6 Comments

When it was announced in 2000 at a Nintendo trade show, the Game Boy Advance was clad in beautiful silver plastic, accented with brilliant orange buttons. As is usually the case with product introductions, the first color and style displayed to be public became the most popular. There was one problem with this silver and orange GBA; Nintendo never put it into production. Fast forward fifteen years, and [Michael Choi] decided it was time to make his own silver and orange Game Boy. It’s a great introduction to mold making and very detailed painting, and a useful guide for turning engineering prototypes into beautiful objects.

[Michael]’s build began with an aftermarket shell, painted with Tamiya spray paints. The color is remarkably accurate, considering the only pictures for the silver and orange Game Boy are fifteen years old, and with the right painting technique, these colors are indistinguishable from a properly colored, injection molded piece of plastic.

The buttons were not as easy as the shell. [Michael] originally decided casting would be the best solution, but after multiple attempts, he couldn’t get the color right. Even with opaque dyes in the resin, the buttons would still come out slightly translucent. In the end, [Michael] decided to paint the original buttons.

This casemod isn’t just about changing the color of the enclosure. [Michael] also wanted is Game Boy to have the backlight found in the second revision clamshell GBA. This was easily acquired on eBay, and with a few slight hardware modifications and a beautiful glass lens to replace the plastic occupying the bezel, [Michael] has a gorgeous Game Boy Advance, taken straight from a press event fifteen years ago.

This Post Will Self Destruct In 10 Seconds

September 15, 2015 by James Hobson 62 Comments

Ah yes, the classic Mission Impossible ultimate message security — after verification and playing the message, poof — it’s gone. You could design explosives into your electronics to have the same effect… or you can use Xerox PARC’s new chip, which features a self-destruct mode.

Wait, what? Yup — some engineer at Xerox decided to develop a chip that can literally self-destruct. It was developed for DARPA’s vanishing programmable resources project, and well, it sounds pretty promising for the future of high-security applications. Continue reading “This Post Will Self Destruct In 10 Seconds” →