Year: 2014

Making A Variable RF Signal Sampler

January 16, 2014 by 18 Comments

One of [Brian]’s hobbies is Amateur Ham radio, in which it is usually required to check that the transmitted signals are within specifications. As it isn’t safe to connect the radio’s output directly to measuring equipment due to the high voltages involved, [Brian] made his own dedicated RF signal sampler. It works by using capacitive coupling between the signal you wish to sample and a high impedance output. The latter can then safely be connected to an oscilloscope or spectrum analyzer for monitoring.

In the picture you see above, the air gap between the core signal conductor and the output plays the role of a capacitor. By adjusting its length you can therefore vary the output signal’s voltage range. The sampler is built using a die-cast aluminium enclosure which is 52x38x27mm. As you may have guessed, due to the case geometry the output attenuation will depend on the signal’s frequency. [Brian] tested the unit using a 30MHz signal generator and printed this frequency attenuation graph while also varying the air gap.

Fail Of The Week: Color Meter For Adjusting LEDs

January 16, 2014 by 29 Comments

fotw-color-meter

[John Peterson] answered our call to document your hacks by discussing what he learned while building this color meter. He conceived the project as a way to precisely match the color output of LEDs driven with a PWM signal. The thought was that it could sample an LED’s output, then use that data to calculate values necessary to match the color of other LEDs. This is a good idea when using LEDs of different types, but even diodes from the same production line can show variations in color output.

Of course this project wouldn’t be featured as a Fail of the Week if it worked as he had expected. It turns out the sensor that he used, an Avago ADJD-S371-QR999 on a SparkFun breakout board, takes very quick color readings. This is great for solid objects, but not great for a light source being switched on and off like the PWM LEDs.

We like it that [John] posted a list of lesson learned on the project. The real fail is in trying to use this particular sensor, but we figure there must be some way to get meaningful data through sampling. Check out the page for the retired sensor which also includes a link to the datasheet. Can you think of a firmware hack which would allow this hardware to sample so that the PWM value could be extrapolated through averaging or other calculations? Let us know in the comments.

2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Build A Cheap Airplane ADS-B Radio Receiving Tracking Station

January 16, 2014 by 30 Comments

Do you have commercial or general aviation flying over your home or near your home? Would you like to know more about these airplanes: identity, heading, speed, altitude and maybe GPS data along with even more information? Well then [Rich Osgood] has just the project for you and it’s not that expensive to set up. [Rick] demonstrates using a cheap USB dongle European TV tuner style SDR (software defined radio) tuner that you can get for under $30 to listen in on the Automatic Dependent Surveillance-Broadcas (ADS-B) (dead link, try the Internet Archive version) 1090 MHz mode “S” or 978 MHz mode “UAT” signals being regularly transmitted from these aircraft.

He steps us through configuring the radio to use a better antenna for improved reception then walks through detailed software installation and set up to control the radio receiver as well as pushing the final decoded data to mapping software. This looks like a fascinating and fun project if you live near commercial airways. You won’t need a license for this hack because you’re only listening and not transmitting, plus these are open channels which are legal to receive.

There are some frequencies you are not legally allowed to eavesdrop on—private communications for residential wireless telephones and cellular frequencies to name just a few (Code of Federal Regulations Title 47, Part 15.9). So remember you do have to be careful and stay within legal frequencies even if your equipment is not restricted from such reception. Also note that just because you have a legal right to intercept conversations or data on some frequencies it could be illegal to publicly share the intercepted content or any details on the reception or decoding (just saying for the record).

We wonder if [Rick] could partner with [G. Eric Rogers] to upgrade [Eric’s] motorized telescope airplane tracking system to extrapolate the radio telemeter data into vector data so his Arduino can track without relying on a video feed. That merger might just get them both on a short TSA list.

Join us after the break for some extra informational links and to watch the video on setup, installation and usage of this cheap airplane tracking rig.

Continue reading “Build A Cheap Airplane ADS-B Radio Receiving Tracking Station” →

Cheap (Free?) Mirror Replacement For Your CO2 Laser

January 16, 2014 by 30 Comments

hdd mirrors

You know what’s expensive? Those little tiny little mirrors used in laser cutters — and they don’t last forever either! What if we told you it’s possible to make your own for free, using a broken hard drive?

[Tim Wehr] read about using HDD platters as mirrors on BuildLog.net, and decided to try it out for himself to see how well they work. He quickly salvaged an old hard drive and removed the ever so shiny platters. Using a few pieces of wood he clamped the platter and then cut circles out of it using a metal hole saw — the edges are a bit rough, so we’d recommend you invest in a diamond hole saw if you’re planning on trying this.

Some denatured alcohol polishing later and a bit of filing on the edges, and he had a replacement mirror. He then performed two tests using both the original and the HDD mirror on his CO2 laser. Almost identical cutting power. In fact, [Tim] muses that the HDD mirror looks like it cut slightly better even! Not bad!

[Thanks Riva!]

Hackintosh Mac Pro Replica Using A Trash Can

January 16, 2014 by 68 Comments

An anonymous German case modder decided to poke fun at the new Mac Pro… by making his own Hackintosh Pro out of a trash can!

For whatever reason the German forum it spawned in is a little bit secretive, but [Dschijn] of tonymacx86.com got permission to share the build on the creator’s behalf — and it is absolutely glorious.

The beautiful exterior is a Authentics Lunar 6L trash can, painted a vibrant pink — complete with a fake Apple logo. Inside is a Gigabyte Mini ITX motherboard, a Haswell i3 processor, a Radeon 7750, an SSD, a HDD, an ATX power supply, and an undisclosed amount of RAM. True to the Mac Pro, it features a central airflow design, with a fancy hand-crafted intake grate on the bottom.

While its technical specs fail to impress, it is remarkably similar in size to the real deal, varying by just under an inch.

[via Ars Technica]

A Light-Up Dress For A New Year’s Dance Party

January 15, 2014 by 5 Comments

wearableLedress

Don’t let the above picture’s lack of blinking colors fool you, the light-up dress [Sam] fashioned for his girlfriend is rather eye-catching; we’d just rather talk about it than edit the gifs he’s provided. [Sam’s] been a busy guy. His last project was a Raspberry Pi digital photo frame, which we featured just over a week ago, but wearable hacks allow him to combine his favored hobbies of sewing and electronics.

If you’re looking to get started with wearable electronics, then this project provides a great entry point. The bulk of the build is what you’d expect: some individually-addressable RGB LEDs, the ever-popular FLORA board from Adafruit, and a simple battery holder. [Sam] decided to only use around 40 of the LEDs, but the strips come 60 to a meter, so he simply tucked the extra away inside the dress and set his desired limits in the software, which will allow him to preserve the entire strip for future projects. If you’ve ever attempted a wearable hack, you’re probably familiar with how delicate the connections can be and how easily the slightest bend in the wiring can leave you stranded. Most opt for a conductive thread solution, but [Sam] tried something different and used 30 AWG wire, which was thin enough to be sewn into the fabric. As an added bonus, the 30 AWG wire is insulated, which permits him to run the wires close to (or perhaps over) each other while avoiding shorts. [Sam’s] guide is detailed and approachable, so head over to his project page if you think you’ve caught wearables fever, and check out his GitHub for the source code.

Miniscule Line-Follower

January 15, 2014 by 16 Comments

miniscule-line-follower

Building line following robots is fun and easy. Building a line-follower that is this tiny is a different story. The surprising thing for us is that despite how it looks, this robot whose name is Rizeh doesn’t use wheels to get around. [Naghi Sotoudeh] built the line-follower using two vibrating motors, with needles (not shown above) making three points of contact with the ground.

His website is a little sparse, but hit the downloads page to get a PDF file that serves as the build log. We also downloaded the 32 second demo video which is worth it. The magic-marker track that the bot is circumnavigating isn’t any bigger than the palm of your hand!

Onboard the diy PCB you’ll find two GP2S04 IR reflectance sensors which detect the black line on a white paper. The power-up sequence spends a few seconds calibrating these sensors. Speaking of power, [Naghi] went with a lithium polymer cell from a Bluetooth headset. At the heart of it all is an ATtiny45 which uses its hardware PWM capabilities to drive the two motors.

Of course line-followers rank up there with self-balancers as our favorite robot projects. But by far the ones we love the most are the speed-run maze solvers.