Month: April 2017

Afroman Makes A UHF Oscillator From A Potato

April 30, 2017 by 18 Comments

If you have ever worked with simple logic gates, there is a good chance that at some point you will have built a ring oscillator from a chain of inverters. With the addition of a resistor and a capacitor, you can easily make a square wave oscillator up into the megahertz range with standard logic chips.

[Afroman] received some rather special logic chips, from an unexpectedly named company, Potato Semiconductor. They specialise in making versions of common 74 series logic that smash the usual 100+ MHz barrier of the faster conventional 74 series chips, and extend their bandwidth up to over 1 GHz. Using one of their 74GU04 parts, he made a ring oscillator relying only on the stray capacitances of its gate inputs for its timing, and while he didn’t manage to achieve a GHz he did measure it at about 373 MHz. He took a look with a spectrum analyser, and as you might expect from a logic circuit found strong harmonics in the GHz range.

Now normally there would be no news in someone making a ring oscillator with a 7404. It really wouldn’t be a hack with a run-of-the-mill 74LS or 74HC part. But this Potato part is sufficiently unusual that it deserves a bit of attention in its own right. After all, we’re not used to logic chips that can work at those kinds of frequencies.

We’ve put his video below the break. Meanwhile, the Potato Semiconductor website makes for an interesting browse, and proves that there is plenty of life left in the venerable 74 series.

Continue reading “Afroman Makes A UHF Oscillator From A Potato” →

The Mother Of All Belt Grinders

April 29, 2017 by 33 Comments

It seems like everyone is building belt grinders these days. You might think [Jeremy Schmidt] is just hoping on the bandwagon, but you’d be wrong. He took a full two years to design the perfect belt grinder for his needs. Now he’s built his perfect beast, and we must say, it’s quite impressive!

[Jeremy] had seen grinders which can tilt, but most of them tilt the entire machine, including the table. He designed his machine with an independent table. This means the belt can be placed at any angle, while the table remains flat. He’s achieved some really interesting finishes with a course grind on a 45-degree angle to the workpiece.

No build is without its problems. In [Jeremy’s] case it was building the box which acts as a receiver for the machine and the tables. Regular square tube stock wasn’t quite rigid enough, so bar stock was the way to go. The first attempt at building the box resulted in a warped tube, due to the stresses of welding. [Jeremy] was more careful the second time, moving from section to section of the four welds. This kept the heat from building up, and the box stayed straight.

The final result is an incredibly rigid machine which definitely will withstand anything that [Jeremy] can throw at it.

If you want to see more belt grinders at work, check out [Bob]’s treadmill belt grinder, or [Mike’s] conversion.

Continue reading “The Mother Of All Belt Grinders” →

A LED Strip Clock As Linear As Time

April 29, 2017 by 9 Comments

We love custom clocks here at Hackaday, and are always thrilled to see each inventive means of time-keeping. In a seldom-seen take on the familiar device, the [Bastel Brothers]’s LED Strip Clock’s sleek profile finds itself in good company.

The clock is a two-metre strip of 60 LEDs; every minute past the current hour corresponds to one lit LED, every fifth LED is turned to red in order to make reading minutes easier. So 3 red LEDs +3 green LEDs=18 minutes, with the hour marked by a third color. Sounds complex, but the [Brothers] are quick to say you get used to it quickly, especially when the 6 o’clock LED is centered at some noticeable object or feature.

Continue reading “A LED Strip Clock As Linear As Time” →

Linger Keeps You Around After You’ve Gone

April 29, 2017 by 40 Comments

We’re not sure if this is art, anti-snooping guerilla warfare, or just a cheeky hack, but we do know that we like it! [Jasper van Loenen]’s Linger keeps the SSIDs that your cell phone (for example) spits out whenever it’s not connected to a WiFi network, and replays them after you’re gone.

Some retail stores and other shady characters use MAC addresses and/or the unique collection of SSIDs that your phone submits in probe requests to fingerprint you and track your movement, either through their particular store or across stores that share a tracking provider. Did you know that you were buying into this when you enabled “location services”? Did the tracking firms ask you if that was ok? Of course not. What are you going to do about it?

Linger replays the probe requests of people who have already moved on, making it appear to these systems as if nobody ever leaves. Under the hood, it’s a Raspberry Pi Zero, two WiFi dongles, and some simple Python software that stores probe requests in a database. There’s also a seven-segment display to indicate how many different probe-request profiles Linger has seen. We’re not sure the price point on this device is quite down to “throwie” level, but we’d love to see some of these installed in the local mall.  Continue reading “Linger Keeps You Around After You’ve Gone” →

Hackaday Prize: An Autonomous Beach Art Robot

April 29, 2017 by 26 Comments

Some people find it hard to look at a huge, flat expanse of floor or ground and not see a canvas. From the outfield grass of a baseball park to some poor farmer’s wheat field, trampling, trimming or painting patterns can present an irresistible temptation. But the larger the canvas the more challenging the composition will be, which is where this autonomous beach-combing art robot comes into play.

Very much still a work in progress, [pablo.odysseus]’ beach bot was built to take advantage of the kilometers-wide beaches left by the receding tides near his home. That immense canvas is begging to be groomed, and this bot is built for the task. The running gear itself is simple – an extruded aluminum chassis powered by wheelchair drives with added optical encoders and dragging a retractable rake  – but the bot is bristling with electronics dedicated to navigation.  A pair of Arduinos run the dual odometers, compass, and a GNSS receiver, as well as providing a smartphone interface for on-the-fly changes. The art is composed as a DXF file converted to latitude and longitude points and exported to Google Earth as a KML. That means the bot can just be brought to the beach and allowed to draw autonomously. An early test run is seen below the break; better “brushes” are in the works.

Watching the art unfold on a beach would be relaxing, like watching a zen garden being created. We’re looking forward to [pablo]’s progress on this one. Of course, art bots aren’t the only autonomous machines that big, wide beaches attract.

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The Connected Calculator With ESP8266

April 29, 2017 by 12 Comments

Calculator hacks have been around for a while now and we have seen the most action around the Texas Instruments TI-83 and TI-84. When [johnkimdinh] found a way to add an ESP8266 to a scientific calculator (machine translation) and this time around it’s a Kenko FX-82M calculator which appears eerily similar to the Casio FX-82M.

In his video, [johnkimdinh] demonstrates his hack which has a web interface for transmitting numbers to the calculator. This is accomplished by accessing the keypad using the ESP8266 GPIOs and it is essentially the equivalent of typing remotely. The rest of the circuit remains intact so bit more work and the other functions should be available remotely as well.

Perhaps this hack is best suited as a dedicated display for outputting measurements and other data which requires some type of post-processing to be human readable. If the next iteration delivers the ability to read from the display we’ll really be getting somewhere. We envision such calculators being used as the future of education where the connectivity is used to retrieve an array of real time parameters for assignments. Add a few sensors into the mix and it could be the next big thing for STEM.

In the past, we have had calculators brought to life to do vector and matrix math and ESP8266s connected to TI-84 calculators. After all, everyone has calculators, they simply must be hacked!

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Simple Range Testing For LoRa Modules

April 29, 2017 by 12 Comments

WiFi and Bluetooth have their use cases, but both have certain demands on things like battery life and authentication that make them unsuitable for a lot of low-power use cases. They’re also quite limited in range. There are other standards out there more suitable for low-power and wide area work, and thankfully, LoRa is one of them. Having created some LoRa pagers, [Moser] decided to head out and test their range.

Now, we’ve done range tests before. Often this involves sending one party out with a radio while the other hangs back at base. Cellphones serve as a communications link while the two parties go back and forth, endlessly asking “Is it working now? Hang on, I’ll take a few steps back — what about now?”

It’s a painful way to do a range test. [Moser]’s method is much simpler; set a cellphone to log GPS position, and have the pager attempt to send the same data back to the base station. Then, go out for a drive, and compare the two traces. This method doesn’t just report straight range, either — it can be used to find good and bad spots for radio reception. It’s great when you live in an area full of radio obstructions where simple distance isn’t the only thing affecting your link.

Build details on the pagers are available, and you can learn more about LoRa here. While you’re at it, check out the LoRa tag for more cool builds and hacks.