Year: 2017

A Very Large VU Meter Indeed

May 16, 2017 by 18 Comments

It used to be a must-have on any hi-fi, a pair of moving coil meters or LED bar graphs, the VU meter. Your 1980s boombox would have had them, for example. VU, for “Volume Units”, is a measure of audio level, and the fashion for its visual measure in consumer audio equipment seems now to have largely passed.

The LED bar graph VU meters were invariably driven by the LM3915, a chip that contains a resistor ladder and a stack of comparators which can drive LEDs directly. [Juvar] has taken an LM3915, and used it to drive a set of opto-isolated triacs which in turn drive a stack of appropriately coloured mains LED bulbs concealed within an Ikea Vidja lamp. The result is a huge and very bright VU meter that is as much a lighting effect as it is a measure of sound level.

He’s posted a video of the lights in action, and we’ve placed it below the break. There is a cameo appearance from his cat, and one can’t escape the feeling that it is wasted on a small room and would be at its best before a dance floor. Still, it’s a neat lighting effect and a new use for a classic integrated circuit.

Continue reading “A Very Large VU Meter Indeed” →

Reverse Engineering An Ultrasonic Car Parking Sensor

May 16, 2017 by 18 Comments

It has become a common sight, a must-have feature on modern cars, a row of ultrasonic sensors embedded in the rear bumper. They are part of a parking sensor, an aid to drivers for whom depth perception is something of a lottery.

[Haris Andrianakis] replaced the sensor system on hs car, and was intrigued enough by the one he removed to reverse engineer it and probe its workings. He found a surprisingly straightforward set of components, an Atmel processor with a selection of CMOS logic chips and an op-amp. The piezoelectric sensors double as both speaker and microphone, with a CMOS analogue switch alternating between passing a burst of ultrasound and then receiving a response. There is a watchdog circuit that is sent a tone by the processor, and triggers a reset in the event that the processor crashes and the tone stops. Unfortunately he doesn’t delve into the receiver front-end circuitry, but we can see from the pictures that it involves an LC filter with a set of variable inductors.

If you have ever been intrigued by these systems, this write-up makes for an interesting read. If you’d like more ultrasonic radar goodness, have a look at this sweeping display project, or this ultrasonic virtual touch screen.

Hackaday Prize Entry: Collaborative Water Purification

May 16, 2017 by 63 Comments

Look over any description of a water treatment plant, and you’ll find a description that includes the words, ‘coagulation tanks’. What are these treatment plants coagulating? You don’t want to know. How are they doing it? With chemicals and minerals. Obviously, there’s something else that can be done.

For their Hackaday Prize entry, [Ryan], [designbybeck], [Clint], [Wanda] and [Maker Mark] are investigating electrocoagulation. It’s an alternative to a frothy brew of chemicals that uses electricity to pull pollutants out of the water.

Right now, the tests are much smaller in scale than the tens of thousands of gallons you’d find at a water treatment plant. In fact, the test rig is only a 16-ounce mason jar. While this isn’t large enough to precipitate pollutants out of a household water supply, it is big enough for a proof of concept.

The team is using two electrodes for this build, one aluminum, and one iron. These electrodes are connected via alligator leads to the electronics board they’ve built. This electronics board is basically just an H-Bridge (used so they can reverse the polarity of the field emitter and prevent a buildup of gunk on the electrodes) and a few connectors to a power supply. The results are encouraging; they have a few time-lapse videos of a mason jar of dirty water clearing up with the power of electricity. It’s a great project with some great documentation. The team already has a bunch of updates on their project and instructions on how to replicate their hardware. You can check out those videos below.

Continue reading “Hackaday Prize Entry: Collaborative Water Purification” →

If The I And Q Of Software Defined Radio Are Your Nemesis, Read On

May 16, 2017 by 30 Comments

For those of us whose interests lie in radio, encountering our first software defined radio must have universally seemed like a miracle. Here is a surprisingly simple device, essentially a clever mixer and a set of analogue-to-digital or digital-to-analogue converters, that can import all the complex and tricky-to-set-up parts of a traditional radio to a computer, in which all signal procession can be done using software.

A quadrature mixer. Jugandi (Public domain).
A quadrature mixer. Jugandi (Public domain).

When your curiosity gets the better of you and you start to peer into the workings of a software defined radio though, you encounter something you won’t have seen before in a traditional radio. There are two mixers fed by a two local oscillators on the same frequency but with a 90 degree phase shift, and in a receiver the resulting mixer products are fed into two separate ADCs. You encounter the letters I and Q in relation to these two signal paths, and wonder what on earth all that means.

Continue reading “If The I And Q Of Software Defined Radio Are Your Nemesis, Read On” →

Sip-and-Puff Touchscreens And Grilled Meat During World Create Day

May 16, 2017 by 5 Comments

In the last few weeks, we’ve been seeing a remarkable growth in the entries to The Hackaday Prize. This is due in no small part to World Create Day, a worldwide celebration of building stuff. It’s a worldwide buildathon with hackerspaces all around the globe. Now we’re getting a peek at the results of these gatherings, the videos are posted, and we’re simply gobsmacked by what was created during World Create Day.

Spinal Cord Hacks

The gang over at the Blusson Spinal Cord Center in Vancouver put together a two-day event for World Create Day. The goal of this event was to build a lipsync; a device that enables people with limited use of their hands to use touchscreen devices. It looks like a ray gun, but it’s actually a sip-and-puff device entered into last year’s Hackaday Prize.

Gardening in Cyprus

The Limassol Hackerspace in Cyprus had what is probably the best World Create Day out of all the hackerspaces who took part. Why? Grilled meat, of course.

Instead of trying to improve the entire world, the team at the Limassol hackerspace decided to think locally. Improving their own hackerspace with an automated irrigation system for their vegetable garden, planting vegetables, and building a barbecue took up most of the events of the day. One member even built a few serving platters out of sections of a eucalyptus trunk. These sections of tree cracked, but with the clever application of a CNC router, this hackerspace was able to inlay a few butterflies in the wood. It looks great, and even better with a pile of skewered, grilled meat.

The Osaka Makers’ Space

A few of the members at the Osaka Makers’ Space — like most of us — are interested in miniature robot battles. The first part of the event was, of course, spent tinkering with these tiny robots. A few members of the space made a breakout board for a BLE module, coding it so it could be voice-activated. No, that’s probably not the best way to control a battling robot, but you should do what you want, not what other people think is best.

Also during World Create Day, a few members of the space built three tiny chairs for children. The kids, unfortunately, were busy watching Sesame Street. But hey, at least the screw holes were doweled up. Also on the roster for Osaka’s World Create Day was fixing a broken MacBook Air. The fan quit, and the repair involved soldering wires from the fan to pads on the motherboard.

La Orotava

The folks at the Orotava Hackerspace put on a great event for World Create Day. Wait, where’s Orotava? It’s a town on the island of Tenerife, in the Canary islands. No, the birds are named after the islands, and the islands are named after the dogs.

While they didn’t have hordes of hackers come to a Hackaday meetup on an island in the middle of the Atlantic (St. Helena meetup, anyone?), the Orotava hackerspace did have a few people show up to discuss Hackaday Prize projects. The interesting projects generated from this discussion included an automatic farming robot, mobility problems for mental patients, and a low-cost bandsaw.

The HackadayPrize2017 is Sponsored by:

Folding Mass Effect Pistol!

May 16, 2017 by 13 Comments

Video game props require a dedicated maker with a repertoire of skills to create. When those props are pulled from the Mass-Effect universe, a little more technological mastery is needed. Bringing those talents to bear,  [Optimistic Geometry] has built a motorized, folding M-3 Predator Pistol!

The gun was modeled in Fusion 360 and 3D printed on an Ultimaker 2 at the  MAKLab Glasgow. [Optimistic Geometry] felt constrained by the laws of our reality, so opted for the smaller firearm thinking it would be an appropriate entry-level challenge. I’m sure you can guess how that went.

There wound up being three main build phases as well as a spring-loaded version to testing purposes. Throughout, [Optimistic Geometry] struggled with getting the parts to latch fully open or closed, as well as working with the small form factor. However, overhauling the motor design — and including some limiters lest it deconstruct itself — a custom latching circuit, and — obviously — a few LEDs for effect, produced a magnificent prop.

Continue reading “Folding Mass Effect Pistol!” →

Don’t Be A Code Tyrant, Be A Mentor

May 16, 2017 by 168 Comments

Hardware hacking is a way of life here at Hackaday. We celebrate projects every day with hot glue, duct tape, upcycled parts, and everything in between. It’s open season to hack hardware. Out in the world, for some reason software doesn’t receive the same laissez-faire treatment. “Too many lines in that file” “bad habits” “bad variable names” the comments often rain down. Even the unsafest silliest of projects isn’t safe. Building a robot to shine lasers into a person’s eyes? Better make sure you have less than 500 lines of code per file!

Why is this? What makes readers and commenters hold software to a higher standard than the hardware it happens to be running on? The reasons are many and varied, and it’s a trend I’d like to see stopped.

Software engineering is a relatively young and fast evolving science. Every few months there is a new hot language on the block, with forums, user groups, and articles galore. Even the way software engineers work is constantly changing. Waterfall to agile, V-Model, Spiral model. Even software design methodologies change — from pseudo code to UML to test driven development, the list goes on and on.

Terms like “clean code” get thrown around. It’s not good enough to have software that works. Software must be well commented, maintainable, elegant, and of course, follow the best coding practices. Most of these are good ideas… in the work environment. Work is what a lot of this boils down to. Software engineers have to stay up to date with new trends to be employable.

There is a certain amount of “born again” mentality among professional software developers. Coders generally hate having change forced upon them. But when they find a tool or system they like, they embrace it both professionally, and in their personal projects. Then they’re out spreading the word of this new method or tool; on Reddit, in forums, to anyone who will listen. The classic example of this is, of course, editors like the vi vs emacs debate.

Continue reading “Don’t Be A Code Tyrant, Be A Mentor” →