Author: Jenny List

3313 Articles

Hackaday Prize Entry: Device For Seismic Noise Analysis

May 6, 2017 by 24 Comments

Whenever there is an earthquake somewhere in the world, our TV screens fill with images of seismic data. Those news report graphics with simplified bite-sized diagrams that inform the masses, but usually get something wrong. Among the images there will invariably be one of a chart recorder drawing a significant earthquake trace on paper, which makes good TV, but is probably miles away from the state of the art in seismology.

We are not seismologists here at Hackaday, so it was extremely interesting to find [Michael D]’s project, Device for Seismic Noise Analysis. In it, he gives a basic primer in seismic sensors, and outlines his take on the subject, a sensitive wideband seismic sensor designed to capture the seismic background noise. It seems that many seismic sensors are designed to capture big events, yet ignore the noise between them from which using suitable software one can glean advance warning of seismic events.

The sensor is a simple design, a ball of significant mass rests upon three piezoelectric microphone elements spaced at 120 degree intervals. An extremely high impedance op-amp circuit converts and integrates the charge from the piezo element to a voltage that can be read by an Arduino Yun which harvests the data. It is a bold claim, but the device is said to have already given advance warning of minor seismic events near its Tennessee test site.

Seismology has featured here a few times before. There was this seismometer using a subwoofer as its sensor, and this project using commercial geophones, just to name a couple of examples.

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Hackaday Prize Entry: Arduino Splash Resistant Toilet Foamer

May 4, 2017 by 42 Comments

There are some universal human experiences we don’t talk about much, at least not in public. One of them you’ll have in your own house, and such is our reluctance to talk about it, we’ve surrounded it in a fog of euphemisms and slang words. Your toilet, lavatory, john, dunny, khazi, bog, or whatever you call it, is part of your everyday life.

For his Hackaday Prize entry, [VijeMiller] tackles his smallest room head-on. You see, for him, the chief horror of the experience lies with the dreaded splashback. Yes, a bit of projectile power dumping leaves the old rump a little on the damp side. So he’s tackled the problem with some maker ingenuity and installed an Arduino-controlled foam generator that injects a mixture of soap and glycerin to fill the bowl with a splash-damping load of foam. Rearward inundation avoided.

The parts list reveals that the foam is generated by a fish tank aerator, triggered by a relay which is driven by an Arduino Uno through a power transistor. A solenoid valve controls the flow, and a lot of vinyl tubing hooks it all together. There is an HC/06 Bluetooth module with an app to control the device from a phone, though while he’s posted some Arduino code there is no link to the app. There are several pictures, including a cheeky placement of a Jolly Wrencher, and a shot of what we can only surmise is a text, as foam overflows all over the bathroom. And he’s put up the video we’ve placed below the break, for a humorous demonstration of the device in action.

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We’ve Got It Down PAT: Appliance Electrical Safety Testing

May 4, 2017 by 23 Comments

Everywhere we look in our everyday lives, from our bench to our bedroom, there are the ubiquitous electrical cords of mains-powered appliances. We don’t give our electrical devices a second thought, but in addition to their primary purpose they all perform the function of keeping us safe from the dangerous mains voltages delivered from our wall sockets.

Of course, we’ve all had appliances that have become damaged. How often have you seen a plug held together with electrical tape, or a cord with some of its outer sheath missing? It’s something that we shouldn’t do, but it’s likely many readers are guiltily shuffling a particular piece of equipment out of the way at the moment.

In most countries there are electrical regulations which impose some level of electrical safety on commercial premises. Under those regulations, all appliances must be regularly tested, and any appliances that fail the tests must be either repaired or taken out of service

In the United Kingdom,where this piece is being written, the law in question is the Electricity At Work Regulations 1989, which specifies the maintenance of electrical safety and that there should be evidence of regular maintenance of electrical appliances. It doesn’t specify how this should be done, but the way this is usually achieved is by a set of electrical tests whose official name: “In-service Inspection & Testing of Electrical Equipment”, isn’t very catchy. Thus “Portable Appliance Testing”, or PAT, is how the process is usually referred to. Join me after the break for an overview of the PAT system.

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Electromechanical Lunar Lander

May 3, 2017 by 24 Comments

One of the smash hits of the 1970s arcade was Atari’s Lunar Lander. A landing craft in orbit around a moon would descend slowly towards the surface, and through attitude and thrust controls the player had the aim of bringing it safely in to land. Many a quarter would have been poured into the slot by eager gamers wanting to demonstrate their suitability for astronaut service.

It was to this game that [Chris Fenton] turned when he was looking for inspiration for the 2016 NYCResistor Interactive show, and the result was a Lunar Lander game with a difference, one in which the gameplay was enacted through a physical lander and lunar surface. In this case the moon in question is a papier-mâché-covered inflatable ball, and the lander is a 3D-printed model on the end of a lead screw. Control is provided by an Arduino, with a rough facsimile of the original control panel and a set of microswitches on the model to detect a crash or a safe landing.

The result is a surprisingly playable game, as can be seen from the video below the break.

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Hackaday Prize Entry: Hacker Calculus

May 1, 2017 by 42 Comments

Mathematics, as it is taught in schools, sometimes falls short in its mission to educate the pupils. This is the view of [Joan Horvath] and [Rich Cameron], particularly with respect to the teaching of calculus, which they feel has become a purely algebraic discipline that leaves many students in the cold when it comes to understanding the concepts behind it.

Their Hacker Calculus project aims to address this, by returning to [Isaac Newton]’s 1687 seminal work on the matter, Philosophiae Naturalis Principia Mathematica. They were struck by how much the Principia was a work of geometry rather than algebra, and they are seeking to return to [Newton]’s principles in a bid to make the subject more accessible to students left behind when it comes to derivatives and integrals. They intend to refine the geometric approach to create a series of practical items to explain the concepts, both through 3D printed items and through electronics.

We can see that this is an approach that has considerable merit, given that most Hackaday readers will have at some time or other sat through a maths lesson and come away wondering what on earth the teacher was talking about and having been baffled by further attempts to explain it through impenetrable maths-speak. If you were the kid who “got” calculus when the relationship between speed and acceleration – another thing we have [Newton] to thank for describing – was explained in your physics lessons, then you will probably understand.

The pair have some Hackaday Prize history, you may remember them from such previous entries as their 3D prints for the visually impaired project from last year.

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Hackaday Prize Entry: High Speed Sampling For The Raspberry Pi

April 30, 2017 by 8 Comments

The Raspberry Pi has become a firm favorite in our community for its array of GPIOs and other interfaces, as well as its affordable computing power. Unfortunately though despite those many pins, there is a glaring omission in its interfacing capabilities. It lacks an analogue-to-digital converter, so analog inputs have to rely on an expansion card either on those GPIOs or through the USB port.

Most people remain content with simple ADCs such as Microchip’s MCP3008, or perhaps a USB sound card for low frequency moving targets. But not [Kelu124], he’s set his sights on something much faster. The original Pi is reputed to be capable of handling a 10Msamples/s ADC, so he thinks its faster successors should be able to work much faster. To that end, he’s created an ADC pHAT which he thinks should be good for twice that figure.

The choice of silicon is a CA3306E, a 6-bit device that’s rated at 15Msamples/S. It’s something of a dated device as is shown by its DIP package, and a quick look through major suppliers shows it to be no longer available. Happily though, when you look at his GitHub repo it emerges that he’s also producing a board based on the ADC08200, so his software is targetable at other chips.

Whether or not you need your Pi to serve as video digitizer or high-speed instrument, it’s useful and interesting to take a look at a board like this one in action. We often don’t use the raw power of our single board computers, and this project proves that should we ever need to, we can.

If ADCs interest you, take a look at [Bil Herd]’s series on delta-sigma ADCs.

Thanks [Fustini] for the tip.

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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.

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