Hackaday Prize Entries: Inventing New Logic Families

One of the favorite pastimes of electronics hobbyists is clock making. Clocks are a simple enough concept with a well-defined goal, but it’s the implementation that matters. If you want to build a clock powered only by tubes and mains voltage, that’s a great skill tester. A relay-based timepiece is equally cool, and everyone should build a Nixie tube clock once in their lives.

For [Ted]’s Hackaday Prize entry, he’s building a clock. Usually, this would be little cause for celebration, but this is not like any clock you’ve ever seen. [Ted] is building this clock using only diodes, and he’s inventing new logic families to do it.

Using diodes as logic elements has been around since the first computers, but these computers had a few transistors thrown in. While it is possible to make AND and OR gates using only diodes, a universal logic gate – NANDs and NORs – are impossible. For the computers of the 1950s, that means tubes or transistors and DTL logic.

For the past few years, [Ted] has been working on a diode-only logic family, and it appears he’s solved the problem. The new logic family includes a NOR gate constructed using only diodes, resistors, and inductors. The key design feature of these gates is a single diode to switch an RF power supply on and off. It relies on an undocumented property of the diodes, but it does work.

Although [Ted] can create a NOR gate without transistors — a feat never before documented in the history of electronics — that doesn’t mean this is a useful alternative to transistor logic. The fan-out of the gates is terrible, the clock uses about 60 Watts, and the gates require an AC power supply. While it is theoretically possible to build a computer out of these gates, it’s doubtful if anyone has the patience to do so. It’s more of a curiosity, but it is a demonstration of one of the most mind-bending projects we’ve ever seen.

You can check out a video of the diode clock below.

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The Foghorn Requiem

Foghorns have been a part of maritime history since the 19th century, providing much needed safety during inclement weather to mariners out at sea. Over time, their relevance has slowly reduced, with advanced navigational aids taking over the task of keeping ships and sailors safe.

The sounds of the foghorns are slowly dying out. Artists [Joshua Portway] and [Lise Autogena] put together the Foghorn Requiem, a project which culminated on June 22nd 2013, with an armada of more than 50 ships gathered on the North Sea to perform an ambitious musical score, marking the disappearance of the sound of the foghorn from the UK’s coastal landscape.

ship_layoutUp close, a foghorn is loud enough to knock you off your shoes. But over a distance, its sound takes on a soulful, melancholy quality, shaped by the terrain that it passes over. The artists tried capturing this quality of the foghorn, with help from composer [Orlando Gough] who created a special score for the performance. It brought together three Brass Bands – the Felling Band, the Westoe Band and the NASUWT Riverside Band, almost 50 ships at sea and the Souter Lighthouse Foghorn to play the score.

Each of the more than 50 vessels were outfitted with a custom built, tunable foghorn, actuated by a controller box consisting of a TI Launchpad with GPS, RTC, Xbee radio and relay modules. Because of the great distances between the ships and the audience on land, the devices needed to compensate for their relative position and adjust the time that they play the foghorn to offset for travel time of the sound. Each controller had its specific score saved on on-board storage, with all controllers synchronized to a common real time clock.

Marine radios were used to communicate with all the ships, informing them when to turn on the controllers, about 10 minutes from the start of the performance. Each device then used its GPS position to calculate its distance from the pre-programmed audience location, and computed how many seconds ahead it had to play its horn for the sound to be heard in time on the shore. The controllers then waited for a pre-programmed time to start playing their individual foghorn notes. The cool thing about the idea was that no communication was required – it was all based on time. Check out the video of the making of the Foghorn Requiem after the break, and here’s a link to the audio track of the final performance.

This is a slightly different approach compared to the Super Massive Musical Instrument that we posted about earlier.

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Cable Butchering For Logic-Level Serial

Early PCs and other computers had serial ports, sometimes as their main interfaces for peripherals. Serial ports still survive, but these days they are more likely to have a USB connection into the main computer. However, when you are working with a microcontroller, you probably don’t want a proper RS232 port with its plus and minus 12 volt signals.

You can get converters that specifically output logic-level signals but you probably can’t pick one up at the local office supply store. They might, though, have a normal USB to serial cable. [Aaron] had the same problem so he hacked into a cable to pull out the logic level signals.

On the one hand, hacks like this are a good inspiration for when you have a similar problem. On the other hand, you probably won’t wind up with the same cable as [Aaron]. He got lucky since the board inside his cable was clearly marked. Just to be sure, he shorted the transmit and receive lines to see that he did get an echo back from a terminal program.

Unsurprisingly, you can also repurpose an ESP8266 to perform this same task. Or, you can use a cable as an I/O device.

Gutting And Rebuilding A Classic Watch

No, that watch isn’t broken. In fact, it’s better.

[Lukas] got so used to his binary-readout ez430 Chronos watch that when the strap disintegrated he had to build his own to replace it. But most DIY wristwatches are so clunky. [Lukas] wanted something refined, something small, and something timeless. So he shoe-horned some modern components, including an MSP430, into a Casio F-91W watch.

The result is a watch that tells time in binary, has a built-in compass, and with some more work will be updatable through an IR receiver that he also managed to fit in there somehow. Now he has the watch that Casio would make today, if fashion had stayed stuck firmly in the early 1990s. (Or not. Apparently, Casio still makes and sells the F-91W. Who knew?)

Anyway, back to an epic and pointless hack. Have a look at the tiny, tiny board that [Lukas] made. Marvel in the fact that he drove the original LCD screen. Dig the custom Kicad parts that match the watch’s originals. To get an accurate fit for the case, [Lukas] desoldered the piezo buzzer contact and put the board onto a scanner, which is a great trick when you need to get accurate dimensions. It’s all there, and well-documented, in his GitHub, linked above.

All in all, it’s an insane hack, but we love the aesthetics of the result. And besides, sometimes the hacking is its own reward.

Hackaday Dictionary: Software Defined Radio (SDR)

We are entering a new era of radio technology. A new approach to building radios has made devices like multi-band cell phones and the ubiquitous USB TV receivers that seamlessly flit from frequency to frequency possible. That technology is Software Defined Radio, or SDR.

A idealized radio involves a series of stages. Firstly, an antenna receives the radio signal, converting it into an electrical signal. This signal is fed into a tuned resonator which is tuned to a particular frequency. This amplifies the desired signal, which is then sent to a demodulator, a device which extracts the required information from the carrier signal. In a simple radio, this would be the audio signal that was encoded by the transmitter. Finally, this signal is output, usually to a speaker or headphones.

A replica foxhole crystal set. Photo: Bill Jackson
A replica foxhole crystal set. Photo: Bill Jackson

That’s how your basic crystal radio works: more sophisticated radios will add features like filters that remove unwanted frequencies or additional stages that will process the signal to create the output that you want. In an FM radio, for example, you would have a stage after the demodulator that detects if the signal is a stereo one, and separates the two stereo signals if so.

To change the frequency that this radio receives, you have to change the frequency that the resonator is tuned to. That could mean moving a wire on a crystal, or turning a knob that controls a variable capacitor, but there has to be a physical change in the circuit. The same is true of the additional mixing stages that refine the signal. These circuits may be embedded deeply in the guts of the radio, but they are still there. This is the limitation with normal receivers: the radio can’t receive a signal that is outside the range that the resonator circuit can tune to, or change the way it is demodulated and processed. If you want to receive multiple frequency bands or different types of signals, you need to have separate pathways for each band or type of signal, physically switching the signal between them. That’s why you have physical AM/FM switches on radios: they switch the signal from an AM radio processing path to an FM one.

Software Defined Radios remove that requirement. In these, the resonator and demodulator parts of the radio are replaced by computerized circuits, such as analog to digital converters (ADCs) and algorithms that extract the signal from the stream of data that the ADCs capture. They can change frequencies by simply changing the algorithm to look for another frequency: there is no need for a physical change in the circuit itself. So, an SDR radio can be tuned to any frequency that the ADC is capable of sampling: it is not restricted by the range that a resonator can tune to. Similarly, the demodulator that extracts the final signal you want can be updated by changing the algorithm, changing the way the signal is processed before it is output.

This idea was first developed in the 1970s, but it didn’t really become practical until the 1990s, when the development of flexible field-programmable gate array (FPGA) chips meant that there was enough processing power available to create single chip SDR devices. Once programmed, an FPGA has no problem handing the complex tasks of sampling, demodulating and processing in a single device.

Most modern SDRs don’t just use a single chip, though. Rather than directly converting the signal to digital, they use an analog front end that receives the raw signal, filters it and converts it down to a fixed frequency (called the intermediate frequency, or IF) that the ADCs in the FPGA can more easily digitize. This makes it cheaper to build: by converting the frequency of the signal to this intermediate frequency, you can use a simpler FPGA and a cheaper ADC, because they don’t have to directly convert the maximum frequency you want to receive, only the IF. As long as the front end can convert a band of signals down to an intermediate frequency that the FPGA can digitize, the SDR can work with it.

bladerf
The BladeRF, a modern SDR device that can receive and transmit signals between 300 MHz and 3 GHz

This flexibility means that SDR devices can handle a huge range of signals at relatively low cost. The $420 BladeRF, for instance, can receive and transmit signals from 300 MHz to 3.8 GHz at the same time, while the $300 HackRF One can work with signals from 1 MHz up to an incredible 6 GHz. The ability of the BladeRF to both receive and transmit means that you can use it to build your own GSM phone network, while the low cost of the HackRF One makes it a favorite of radio hackers who want to do things like make portable radio analyzers. Mass produced models are even cheaper: by hacking a $20 USB TV receiver that contains an SDR, you can get a radio that can, with a suitable antenna, do things like track airplanes or receive satellite weather images. And all of this is possible because of the idea of Software Defined Radio.

[Main image source: DVB dongle by Dsimic on Wikipeda CC-BY-SA]

An Arcade Bar And Hackerspace, All In One

Hamvention was last weekend, and just like Hackaday’s expedition to Maker Faire, it was only fitting to find a bunch of Hackaday fans and take over a bar. This was in Dayton, Ohio, and you would think the nightlife for Hamvention would be severely lacking. Not so, as downtown Dayton is home to Proto BuildBar, a bar, arcade, and hackerspace all wrapped into one.

We’ve heard about Proto BuildBar a few years ago when it first opened. The idea is relatively simple; instead of having a hackerspace, with alcohol and video games on the side, Proto BuildBar is first and foremost a bar, with 3D printing services, a few workstations for soldering, and a few arcade games. It’s the perfect place for an impromptu meetup.

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Hackaday Prize Needs You: Build for Citizen Scientists

Humanity is better when we work together. Nowhere is this more true than when it comes to Citizen Scientists — the concept that scientific advancement isn’t reserved to the trained professionals, but benefits when a larger population of thinkers collaborates with the community of trained researchers. This is the goal of the Citizen Scientist challenge round for the Hackaday Prize. Let’s build something that enables citizens to be scientists.

We’ll divide $20,000 evenly between twenty projects that target Citizen Scientists. Enter now and build your prototype by July 11th for your chance to win. Even better, if you are selected as one of those 20 finalists you’ll compete for the top prizes, $150k and a residency at the Supplyframe Design Lab in Pasadena. Second through fifth place finishers will get $25k, $10k, $10k, and $5k.

ramanPi You love design challenges and this one has powerful potential. We’ve seen builds like this in the finals during previous years of the Hackaday Prize. In 2014, RamanPi was recognized as the 5th place winner. The project seeks to reduce the expense of acquiring a Raman Spectrometer which is used for analyzing chemical substances. The design used parametric models for the optic jigs used by the machine. The idea is that a university could buy their own optics, adjust the models for the properties of those lenses and mirrors, then 3D print the parts to build the apparatus.

open-science-tricorderAlso a winner in 2014, the Open Science Tricorder was recognized as the fourth place finisher. Based on the form factor and functionality of the iconic Star Trek technology, the Open Science Tricorder combines three or more sensor technologies with a user interface. It provides a hands-on experience for students learning about the properties of the world around them, and a handheld sensor suite to anyone interested in undertaking their own research projects.

The Citizen Scientist challenge round begins right now. Get started on your build today and show us what you can do to solve a technology problem with your prototyping skills. Good luck!

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