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Planet hack-day

  • Monday, April 7, 2014 - 13:01
    3D Printed Camera Arm Saves $143

    arm04

    Professional camera equipment is notoriously expensive, so when [Raster's] LCD camera arm for his RED ONE Digital Cinema Camera broke, he was dismayed to find out a new one would run him back $150! He decide to take matters into his own hands and make this one instead.

    The original arm lasted a good 4 years before finally braking — but unfortunately, it’s not very fixable. Luckily, [Raster] has a 3D printer! The beauty with most camera gear is it’s all 1/4-20 nuts and bolts, making DIY accessories very easy to cobble together. He fired up OpenSCAD and started designing various connector blocks for the 1/4-20 hardware to connect to. His first prototype worked but there was lots of room for improvement for the second iteration.  He’s continued refining it into a more durable arm seen here. For $7 of material — it’s a pretty slick system!

    Between making 3D printed digital camera battery adapters,  3D printed camera mounts for aerial photography, affordable steady-cams, or even a fully 3D printed camera… getting a 3D printer if you’re a photography enthusiast seems to make a lot of sense!

     

    Filed under: 3d Printer hacks

  • Monday, April 7, 2014 - 10:01
    Hack A Day Goes Retro in a Computer Museum

    vt100_HAD Our friends over at Hack42 in the Netherlands decided to have some fun with their computer museum. So far, they’ve been able to display the Hack a Day retro site on three classic computers — including an Apple Lisa, a DEC GIGI, and a run of the mill DEC VT100. We had the opportunity to visit Hack42 last October during our Hackerspacing in Europe trip – but just as a refresher if you don’t remember, Hack42 is in Arnhem, in the Netherlands — just outside of Germany. The compound was built in 1942 as a German military base, disguised as a bunch of farmhouses. It is now home to Hack42, artist studios, and other random businesses. The neat thing is, its location is still blurred out on Google Maps! Needless to say, their hackerspace has lots of space. Seriously. So much so they have their own computer museum! Which is why they’ve decided to have some fun with them… To get Hack a Day Retro on these old computers they are using an old Debian Compaq machine as the host computer for the DECServer90m. The DECServer90m is a remote serial port server with 8 configurable serial ports. It’s used as a terminal server for VAX, nicorVAX or other similar computers. It connects using coax Ethernet to be configured. The serial ports can be setup for printers, modems, or in this case, dumb terminals like the DEC VT100, or an Apple Lisa.

    Lisa-HAD

    An Apple Lisa

    The Lisa was one of the first systems to use a mouse and a graphical desktop!

    GIGI_HAD

    DEC GIGI

     The DEC GIGI VK100 is a strange beast. Even DEC did’t know what to think of it and couldn’t properly market the machine, thinking it was just a dumb terminal with color support and some extra gizmo’s like basic and graphics. It looks like a over-sized Commodore C64 but it has some nice connectors on the back, like a current-loop (for serial connections to even older computers than a VAX like a PDP8 minicomputer and three BNC connectors for component color output.)

    They’re currently working on an even more complicated method to get some really old computers to display the page!

    Filed under: classic hacks, computer hacks

  • Monday, April 7, 2014 - 04:01
    Arduino-Controlled Marquee Arrow Points the Way to Whatever You Like

    Reader [pscmpf] really digs the scrolling light look of old marquee signs and as soon as he saw some Christmas lights with G40 bulbs, he was on his way to creating his own vintage-look marquee arrow.

    We must agree that those bulbs really do look like old marquee lights or small vanity globes. [pscmpf] started by building, varnishing, and distressing the wooden box to display the lights and house the electronics. He controls the lights with an Arduino Pro and an SSR controller board. The 24 lights are divided into ten sections; each of these has its own solid-state relay circuit built around an MC3042 as the opto-coupler, with a power supply he made from a scrap transformer.

    [pscmpf] shares some but not all of his code as it is pretty long. There are five patterns that each play at three different speeds in addition to a continuous ‘on’ state. In his demonstration video after the jump, he runs through all the patterns using a momentary switch. This hack proves that Arduino-controlled Christmas lights are awesome year-round.

     

     

    Filed under: Arduino Hacks

  • Monday, April 7, 2014 - 01:01
    Hackaday Links: April 6, 2014

    hackaday-links-chain

    Back in September we saw this awesomesauce wristwatch. Well, [Zak] is now kitting it up. Learn more about the current version, or order one. [Thanks Petr]

    Home automation is from the future, right? Well at [boltzmann138's] house it’s actually from The Next Generation. His home automation dashboard is based on the LCARS interface; he hit the mark perfectly! Anyone thinking what we’re thinking? This should be entered in the Hackaday Sci-Fi Contest, right? [via Adafruit]

    PCB fab can vary greatly depending on board size, number of layers, number of copies, and turn time. PCBShopper will perform a meta-search and let you know what all of your options are. We ran a couple of tests and like what we saw. But we haven’t verified the information is all good so do leave a note about your own experience with the site in the comments below. [via Galactic Studios]

    We recently mentioned our own woes about acquiring BeagleBone Black boards. It looks like an authorized clone board is poised to enter the market.

    Speaking of the BBB, check out this wireless remote wireless sensor hack which [Chirag Nagpal] is interfacing with the BBB.

    We haven’t tried to set up any long-range microwave communications systems. Neither has [Kenneth Finnegan] but that didn’t stop him from giving it a whirl. He’s using Nanobridge M5 hardware to help set up a system for a triathlon happening near him.

    Filed under: Hackaday Columns, Hackaday links

  • Sunday, April 6, 2014 - 22:00
    VCF East: PetPix, Streaming Images To A Commodore PET

    PETaday

    Thought the Vintage Computer Festival would just be really old computers with hundreds of people pecking 10 PRINT “HELLO” 20 GOTO 10? Yeah, there’s plenty of that, but also some very cool applications of new hardware. [Michael Hill] created PetPix, a video player for the Commodore PET and of course the C64.

    PetPix takes any video file – or streaming video off a camera – and converts 8×8 pixel sections of each frame to PETSCII. All the processing is done on a Raspberry Pi and then sent over to the PET for surprisingly fluid video.

    There is, of course, a video of PetPix available below. There are also a few more videos from [Michael] going over how PetPix works.

    Filed under: classic hacks

  • Sunday, April 6, 2014 - 19:01
    Reusable Vacuum Bag Saves you Money

    FTWP5L5FLROLXM5.MEDIUM

    Vacuum dust bags are annoying. They’re expensive, one time use, and if you have an older vacuum cleaner, good luck finding replacements! [Karl] got fed up so he decided to make his own reusable dirt bag instead.

    He’s using an old t-shirt as the new bag material but notes that you can use any other sufficiently drafty material as well — as long as it stops the dust but lets air through, you’re good! To seal the bag he’s using a piece of rubbery vinyl with a hole cut in it to seal against the intake pipe. This is sewn to the t-shirt with a piece of cardboard sandwiching the fabric. From there it’s just a matter of adding a zipper or Velcro, and you’re done!

    He’s been using this filter for over a year and hasn’t had any problems with it yet — you can even wash it! While you’re at it, why not make a wet-spill attachment for your vacuum cleaner too?

     

    Filed under: green hacks

  • Sunday, April 6, 2014 - 16:00
    VCF East: The Swyft Card

    swyft

    Ninety five percent of the population will say Apple computers is the brainchild of [Steve Jobs]. The other five percent will be right, but what nearly no one knows is that the Macintosh project was originally conceived by [Jef Raskin]. He holds the honor of turning the Mac into an, ‘information appliance’ and being one of the first people to seriously consider how millions of people would interact with computers.

    The Mac wasn’t [Jef]‘s first project at Apple, though. Before the Mac project he was working on something called Swyft – an easy to use command line system that was first implemented as a firmware card for the Apple IIe. [Mike Willegal] was kind enough to bring one of these Swyft cards to the Vintage Computer Fest this weekend, and did a demo of it for us.

    The basic idea behind the Swyft card was to have an integrated word processor, calculator, and access to Applesoft Basic. Holding down a ‘leap’ key – in the case of the Apple IIe add-on, the open apple key – allowed the user to search for text and perform operations on any result. It’s odd, but it just makes sense in some strange way.

    [Mike] is doing a build class at the VCF today where anyone attending can build their own Swyft card. He also has instructions for building your own, should you want to experiment with one of the ‘could have beens’ of user interface design.

    Filed under: classic hacks

  • Sunday, April 6, 2014 - 13:01
    CPLD Tutorial: Learn Programmable Logic the Easy Way

    739px-Altera_MAX_7128_2500_gate_CPLD

    The guys over at hackshed have been busy. [Carl] is making programmable logic design easy with an 8 part CPLD tutorial. Programmable logic devices are one of the most versatile hardware building blocks available to hackers. They also can have a steep learning curve. Cheap Field Programmable Gate Arrays (FPGA) are plentiful, but can have intricate power requirements. Most modern programmable logic designs are created in a Hardware Description Language (HDL) such as VHDL or Verilog. Now you’ve got a new type of device, a new language, an entirely new programming paradigm, and a complex IDE to learn all at once. It’s no wonder FPGAs have sent more than one beginner running for the hills.

    The tutorial cuts the learning curve down in several ways. [Carl] is using Complex Programmable Logic Devices (CPLD). At the 40,000 foot level, CPLDs and FPGAs do the same thing – they act as re-configurable logic. FPGAs generally do not store their configuration – it has to be loaded from an external FLASH, EEPROM, or connected processor. CPLDs do store their configuration, so they’re ready as soon as they power up. As a general rule, FPGAs contain more configurable logic than CPLDs. This allows for larger designs to be instantiated with FPGAs. Don’t knock CPLDs though. CPLDs have plenty of room for big designs, like generating VGA signals.

    [Carl] also is designing with schematic capture in his tutorial. With the schematic capture method, digital logic schematics are drawn just as they would be in Eagle or KiCad. This is generally considered an “old school” method of design capture. A few lines of VHDL or Verilog code can replace some rather complex schematics. [Carl's] simple designs don’t need that sort of power though. Going the schematic capture route eliminates the need to learn VHDL or Verilog.

    [Carl's] tutorial starts with installing Altera’s Quartus II software. He then takes the student through the “hardware hello world” – blinking an LED.  By the time the tutorial is done, the user will learn how to create a 4 bit adder and a 4 bit subtractor. With all that under your belt, you’re ready to jump into big designs – like building a retrocomputer.

    [Image via Wikimedia Commons]

    Filed under: FPGA, hardware

  • Sunday, April 6, 2014 - 10:01
    Creative Continuity Tester Made For a Few Bucks

    13595431395_4be0feaf4f_b

    No multi-meter? For troubleshooting most household things, a continuity tester is extremely handy. And as it turns out, you can make your own from the dollar store for next to nothing.

    [Carlyn] shows us how to make two different styles of continuity testers — a light up version using a bicycle light, or a buzzer version using one of those cheap window alarms. The leads are made of 1/8″ audio cables — and everything for both these testers cost less than $5 from their local dollar store. It’s a very simple build process that you can probably figure out just from this one photo, but [Carlyn] has also taken pictures of every step along the way.

    Compared to building one of these out of components from Radio Shack, this method is much more MacGyver, and cheap! Hooray for taking advantage of mass produced consumer products!

    Not functional enough? How about building a talking multimeter instead? No? Have you ever wanted two multi-meters in one? Say hello to the Mooshimeter!

    Filed under: tool hacks

  • Sunday, April 6, 2014 - 07:01
    University Attempts to Break 3D Printing World Record

    lulz

    LeTourneau University attempted to set a 3D printing Guinness World Record yesterday. They had 50 3D printers print the same thing at the same time. Impressive? Kind of, but not really.

    LulzBot — our favorite 3D printer company — saw this and thought “that’s cute — we run over 50 printers a day on a normal basis!”. So just for lulz, they decided to film a little counter-record video featuring 109 LulzBot 3D printers running simultaneously.

    To be honest, we kinda feel sorry for LeTourneau University — but it looks like LulzBot really takes the cake here. The university has a really cool policy for their engineering students though — all incoming freshmen students are required to build their own 3D printer for school. Whoa! To be honest it is a really cool way to force you to get out of your comfort zone and learn a bit about several different engineering disciplines.

    To follow along the discussion and status of the record, a thread is going on over at 3Dprintboard.com. Stick around to see the video of LulzBot’s drool worthy server racks filled with identical printers.

    Filed under: 3d Printer hacks

  • Sunday, April 6, 2014 - 04:00
    Super Mario on a Human-Machine-Interface!

    super mario

    Getting Super Mario to work on your TI-83 calculator is almost a rite of passage for young geeks, so we really liked this project where [Chad Boughton] managed to get it running on a PLC’s HMI screen instead!

    He’s using a Danfoss DP600LX microcontroller with an HMI display along with a CAN bus joystick. This kind of equipment is typically used to control hydraulic systems, as well as display sensor data — [Chad] was curious to see if he could do animation with it as well — it looks like he’s succeeded! The funny thing is we’ve seen those “joysticks” before and it’s cool to see them used for something like this — like [Chad] said, they’re normally used for actuating hydraulic and pneumatic cylinders.

    Stick around after the break to see Mario eat some mushrooms.

    There’s almost too many Mario hacks to mention here, so we’ll just pick  a few — Ever heard the Mario theme song played on a laser cutter? It’s as awesome as it sounds. And for a true Super Mario veteran… can you play it backwards?

    Filed under: misc hacks, nintendo hacks

  • Sunday, April 6, 2014 - 01:01
    Gesture Recognition Using Ultrasound

    SAMSUNG

    You’d be hard pressed to find a public restroom that wasn’t packed full of hands free technology these days. From the toilets to the sinks and paper towel dispensers, hands free tech is everywhere in modern public restrooms.

    The idea is to cut down on the spread of germs.  However, as we all know too well, this technology is not perfect. We’ve all gone from sink to sink in search of one that actually worked. Most of us have waved our hands wildly in the air to get a paper towel dispenser to dispense, creating new kung-fu moves in the process. IR simply has its limitations.

    What if there was a better way? Check out [Ackerley] and [Lydia's] work on gesture recognition using ultrasound. Such technology is cheap and could easily be implemented in countless applications where hands free control of our world is desired. Indeed, the free market has already been developing this technology for use in smart phones and tablets.

    Where a video camera will use upwards of 1 watt of power to record video, an ultrasound device will use only micro watts. IR can still be used to detect gestures, as in this gesture based security lock, but lacks the resolution that can be obtained by ultrasound.  So let us delve deep into the details of [Ackerley] and [Lydia's] ultrasound version of a gesture recognizer, so that we might understand just how it all works, and you too can implement your own ultrasound gesture recognition system.

    Most of us are aware of the Doppler Effect – the compressing and stretching of waveforms as the source moves toward or away from a point. Consider a device that consists of a tone generator above the 20kHz human ear threshold (ultrasound) and a microphone transducer that would react to reflections of the ultrasound waveform. If an object, such as a hand, were moving toward the device, the reflected waveform would experience a Doppler shift. Such a shift would be seen by the microphone. The same would happen if the object were moving away from the device. This frequency shift can be calculated by:

     

    ultrasound01

     

    In order to determine if an object is moving toward or away from the device, you must compare the outgoing and incoming frequencies. [Ackerley] and [Lydia] decided to use the Fast Fourier Transform equation to do this – the same technique used by Microsoft’s Sound Wave, which inspired their project. Unfortunately their assigned processor, the Atmel 1284p, would not be able to handle the Fast Fourier Transform AND signal acquisition at the same time. It was just not fast enough. Stumped, their instructor suggested a clever idea. An idea that will open up gesture recognition via ultrasound to the world of the 8 bit micro controller. You see, instead of doing the frequency comparison on the resource limited digital side, do it on the analog side with an AD633 Analog Multiplier IC (pdf warning).

    It turns out that if you multiply two sine waves, you will get two different products. One will be the difference and the other will be the sum of the two waveforms. There is beauty in this. Our paradigm has shifted. This single 8 pin IC can determine the difference in frequency between the incoming and outgoing signals. Consider an outgoing frequency of 24kHz. Now consider a hand moving toward the device creating a Doppler shifted frequency of 24.1kHz. The output of the AD633 would be 1kHz and 48.1kHz.  The 48.1kHz is easily filtered away and you are left with the 100Hz, or the difference between the incoming/outgoing frequencies that an 8 bit micro controller can easily sample.

    Now a keen eye will see that the Doppler shifted frequency only reveals magnitude, and not direction. [Ackerley] and [Lydia] solve this problem by observing subtle changes in amplitude of the difference frequency. Many more details of how this is done can be found in the linked article. The image below show’s their algorithm in the Atmel detecting a “pull” motion.

     

    ultrasound03

     

    The genius of this project is that a viable gesture recognition system can be implemented with cheap components. The approach of doing a similar system with a PC or smart device would be different. We would like to see the microcontroller side pushed further. Imagine a system in an elevator where the passenger could “draw” the number to the floor he or she wanted to go to. Or a paper towel system that would dispense towels as we twirled our hand, and stop when we stopped twirling. Or a sink that could change water temperature with a simple gesture. Such systems, using the technology designed by [Ackerley] and [Lydia], should be possible.

    Filed under: Microcontrollers, misc hacks

  • Saturday, April 5, 2014 - 22:01
    Open Source Power Line Communication

    Power Line Communication Filtering

     

    Since we all have wires running throughout our houses to provide mains power, there’s a number of devices that piggyback on mains lines for communication. For his thesis project, [Haris Andrianakis] developed his own power line communication system.

    The basic principle of the system is to inject a signal onto the power lines at a much higher frequency than the 50 or 60 Hz of the AC power itself. Using both active and passive filters, the signal can be separated from the AC power and decoded. This system uses frequency-shift keying to encode data. This part is done by a ST7540 modem that’s designed for power line applications. The modem is controlled over SPI by an ATmega168 microcontroller.

    [Haris]‘ write up goes into detail about some of the challenges he faced, and how to protect the device from the high voltages present. The final result is a remote display for a weigh scale, which communicates over the power line. Schematics, PCB layout, and software are all available.

    Filed under: hardware, home hacks

  • Saturday, April 5, 2014 - 19:01
    The Mobile Phone PixelSWaLL

    mobile pixel wall

    As much as we hate to admit it, smart phones have become somewhat of a disposable item in today’s society. People upgrade their phones constantly and simply chuck their old ones. Of course, there’s plenty of things you can do with slightly out of date phones… Here’s one we haven’t seen before — a wireless multi-phone display!

    It’s called the PixelSWaLL, and according to the author,  his software can control up to 240 Android devices! To run this demo with just 9 phones, he’s using an old Apple Macbook running Windows 7 bootcamp, which sends the display info using an old Telmex router. Each phone or tablet runs the Android terminal application  using Eclipse ADT which renders OpenGL in real-time. The server application was made with Delphi 7 and uses the DSPack library to read video files in order to send them over UDP via Indy 10. It’s a bit of a mouthful to explain, but the resulting display array is pretty cool!

    Time to start collecting phones…

    [Thanks Axel!]

    Filed under: Android Hacks

  • Saturday, April 5, 2014 - 16:01
    Bike Pedals in Both Directions, Gets You to Your Destination AND Back

     

    pedalbackward

    [punamenon2] has built an interesting bike that moves forward regardless if it is pedaled forward or backwards! What? Yes, you read that correctly. Pedal forward or backwards and the bike goes forward. This project started off as any old cruiser with a free-wheeling rear hub. To pull off this mod a second free-wheel and sprocket had to be added to the current wheel assembly. One free-wheel and sprocket set is used when pedaling forward, the other set is used when pedaling in reverse. There is also a new chain tensioner that serves to not only keep the chain taut but also allows for the chain to change directions which ultimately allows this novel idea to work.

    Confused? Here’s how it works:

    When pedaling in the forward direction, the bike acts as a normal bike does where top of the Crank Sprocket pulls the chain and the chain then pulls on the top of the Large Wheel Sprocket. This turns the rear wheel in the forward direction. The portion of the chain that wraps around the Small Wheel Sprocket is traveling in the backward (CCW) direction which doesn’t cause a problem because it is a freewheel, just like how you can pedal backwards on a bike while coasting forward. Since there are two different sized Wheel Sprockets, pedaling in the forward direction is the higher of the two gears.

    When pedaling backwards the chain moves in the opposite direction. The bottom of the Crank Sprocket pulls the chain forward which in-turn pulls on the top of the Small Wheel Sprocket. This also turns the rear wheel in the forward direction. The portion of the chain that wraps around the Large Wheel Sprocket is now traveling in the backward (CCW) direction, and again doesn’t cause a problem because it is freewheel.

    pedalforward

    Why did [punamenon2] decide to do this? Just for fun! And that is a good enough reason in our book.

    [via Reddit]

    Filed under: transportation hacks

  • Saturday, April 5, 2014 - 13:01
    Taking Pictures with a DRAM Chip

     

    DRAM Image

    This picture was taken by using a DRAM chip as an image sensor (translated). A decapped 64k DRAM chip was combined with optics that could focus an image onto the die. By reading data out of the DRAM, the image could be constructed.

    DRAM is the type of RAM you find on the RAM cards inserted into your motherboard. It consists of a massive array of capacitors and transistors. Each bit requires one transistor and one capacitor, which is quite efficient. The downside is that the memory needs to be refreshed periodically to prevent the capacitors from discharging.

    Exposing the capacitor to light causes it to discharge faster. Once it has discharged past a certain threshold, the bit will flip from one to zero. To take a picture, ones are written to every bit in the DRAM array. By timing how long it takes a bit to flip from one to zero, the amount of light exposure can be determined. Since the DRAM is laid out in an array, each bit can be treated as a pixel to reconstruct the image.

    Sure, modern CCDs are better, cheaper, and faster, but this hack is a neat way to totally re-purpose a chip. There’s even Turbo Pascal source if you’d like to recreate the project.

    Thanks to [svofski] for the tip.

    Filed under: digital cameras hacks

  • Saturday, April 5, 2014 - 10:01
    Web Interface for the FRAM LaunchPad

    webUILaunchpad The Internet of Things is here in full force. The first step when adding to the Internet of Things is obvious, adding a web interface to your project. [Jaspreet] wrote in to tell us about his project that adds a web interface to his MSP430 based project, making it easy to add any project to the internet of things.

    Creating a web interface can be a bit overwhelming if you have never done it before. This project makes it easy by using a dedicated computer running Linux to handle all of the web related tasks. The LaunchPad simply interfaces with the computer using USB and Python, and the computer hosts the webpage and updates it in real time using Node.js. The result is a very professional looking interface with an impressively responsive display that can control the on-board LEDs, read analog values from the integrated ADC, and stream accelerometer data. Be sure to see it in action after the break!

    We could see this project being expanded to run on the Raspberry Pi with a multitude of sensors. What will you add a web interface to next? Home automation? A weather station? Let us know!

    Filed under: internet hacks

  • Saturday, April 5, 2014 - 07:01
    Robot Cage Fighting is Still a Thing!

    1463025_550690488347294_1038503674_n

    Remember Battlebots? Turns out it is alive and well in Southern California at the National Tooling and Machining Association (NTMA) Robotics League. That’s right — high school students are getting to build remote controlled weaponized robots to battle to the death inside a poly-carbonate octagon arena. Awesome.

    [Bradley Hanstad] wrote to us today to inform us of the 2014 Regional Competition — happening tomorrow at 10AM (PDT). We can’t make it there ourselves, but there is a live stream for everyone to see!

    The league started just this fall which currently consists of 15 area high schools, community colleges, and technical schools. The goal of the league is to spark an interest in engineering and manufacturing in young students, while at the same-time providing hands-on education on the applied side of the sciences. It’s sometimes tricky to get students engaged in engineering competitions — but as soon as you say fighting robots you will have most peoples’ attention.

    To see a teaser trailer for what is to come at these competitions, stick around after the break!

     

    Filed under: robots hacks

  • Saturday, April 5, 2014 - 04:01
    Powering a RPi with Hydrogen

    raspberryHy

    Looking for a new way to power your Raspberry Pi? The raspberryHy project aims to develop a small fuel cell designed for powering the credit card sized computer. It adds a proton exchange membrane (PEM) fuel cell, a battery, and custom control electronics to the Pi.

    The system takes hydrogen in from a compressed hydrogen cartridge and feeds it through a regulator. This passes the hydrogen into the PEM fuel cell at the correct pressure, and creates a potential. The control electronics boost that voltage up to the 5 V required on the Pi’s USB port. There’s also an electronically controlled purge valve which periodically exhausts the fuel cell.

    There’s a few reasons you might want to run your Pi with hydrogen. Run time of the fuel cell is limited only by the amount of hydrogen you can store. In theory, you could connect a large cylinder for very long run times. Combined with a battery, this could be quite useful for running Pis in remote locations, or for long-term backup power. The raspberryHy will be presented at Hannover Fair 2014 this month.

    Filed under: green hacks, Raspberry Pi

  • Saturday, April 5, 2014 - 01:01
    Building an Inductive Loop Vehicle Detector

    [Trax] was asked by a friend to build a device that could detect the presence of a car in front of his garage gate for it to open automatically. After searching the web for such a project and trying many of them, he decided to build his own detector based on an induction loop. As you may have guessed, this kind of detector works by detecting an inductance change in a wire loop (aka coil) buried in the road. Having a car pass several inches on top of it produces such an effect.

    [Trax]‘s write-up shows a very well thought and professional design. All the detector parameters can be adjusted using DIP switches and buttons: detection type (presence/pulse), signal filtering, main frequency and sensitivity. The wire loop is isolated from the main sensor electronics using a 1:1 isolation transformer and a Colpitts oscillator is used to drive the latter. Moreover, gas discharge tubes are also used for lightning protection.

    The change in inductance translates to a change in resonant frequency which is later detected by the main microcontroller. The board is 24V AC powered and a diode bridge + LM2596 SMPS step-down converter are in charge of generating the required +5V in an efficient way.

    As if this was not enough, [Trax] also made a PC-based tool that can change other platform settings using a serial connection. All the resources can be downloaded from his website and a few videos are embedded after the break.

    Filed under: hardware, transportation hacks

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