Hacking An Old Radar Gun To Interface With A Laptop

November 1, 2012 by Mike Szczys 24 Comments

[Gregory Charvat] decided to see what he could do with this old Police radar gun. It is an X-band device that broadcasts continuous waves and measures the Doppler shift as they echo back. He cracked it open to see if he could interface the output with a computer.

After a little poking around he’s able to get it connected to a 12V feed from his bench supply, and to monitor the output with an oscilloscope. He established that it draws about 0.5A in current he built a companion board which uses AA batteries for power, and provides an audio output which can be plugged into his laptop’s audio-in jack. This technique makes reading the device as easy as recording some audio. From there a bit of simple signal processing lets him graph the incoming measurement.

In the video after the break you’ll see his inspection of the hardware. After making his alterations he takes it into the field, measuring several cars, a few birds, and himself jogging.

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Discrete FPGA Will Probably Win The 7400 Logic Competition

November 1, 2012 by Brian Benchoff 19 Comments

For this year’s 7400 logic competition, [Nick] decided to build an FPGA out of logic chips (Internet Archive cached version).

Perhaps a short explanation is in order to fully appreciate [Nick]’s work. The basic component of an FPGA is a slice, or cell, that performs boolean operations on its input and sends the result on its output. The core of these slices is a lookup table – basically a truth table that stores the result of every possible input combination.

One very easy way to implement a lookup table is to use a RAM or EEPROM chip. By tying the address lines of an EEPROM to the input and the data lines to the output, it’s possible to create a single slice of an FPGA very easily.

Unfortunately for [Nick], 74-series memories have long been out of production. There is another option open, though: shift registers. A shift register is basically an 8-bit memory chip with parallel inputs, so combining a shift register with an 8-input multiplexer is a very simple way to implement a 3-input, 1-output FPGA slice.

After figuring out how to tie these slices to bus lines, [Nick] needed a way to program them. Verilog or VHDL would border on insanity, so he wrote his own hardware description language. It’s certainly not as powerful or capable as the mainstream solutions to programming an FPGA, but it’s more than enough.

In the video after the break, you can see [Nick]’s overview of his very large 8-slice FPGA while he runs a combination lock and PWM program. All the code, schematics, and board layout are up on [Nick]’s git if you’d like to build your own.
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PWM On The Stellaris Launchpad

October 31, 2012 by Brian Benchoff 20 Comments

[Joonas] has been following TI’s ‘getting started’ tutorials for their new Stellaris Launchpad. Everything had been going swimmingly until [Joonas] reached the fourth tutorial on interrupts. To the ire of LEDs the world over, implementing PWM on the new Stellaris Launchpad is a somewhat difficult task. After banging his head against the documentation for hours, [Joonas] finally cracked his PWM problem and decided to share his discoveries with the world.

The Stellaris has a PWM mode for its six hardware timers, but unfortunately there are no PWM units on the chip. Solving this problem required making two 16-bit timers out of a single 32-bit one. This allowed [Joonas] to specify a ‘load’ and ‘match’ value.

After coding this up, [Joonas] discovered the PWM timer only works on two of the Launchpad’s pins. Hours of Googling later, he had real PWM on his Stellaris Launchpad.

Given the amount of time [Joonas] spent on this problem, we’re glad to help all the other frustrated Stellaris tinkerers out there by sharing this.

Myst Book Plays Myst, Doesn’t Transport You To Other Ages

October 30, 2012 by Brian Benchoff 58 Comments

We shouldn’t have to remind you, but back in the early 90s one of the most popular computer games was Myst. Despite having the gameplay of a PowerPoint presentation, Myst went on to become one of the best-selling video games of all time and the killer app that made a CD-ROM drive a necessity rather than a luxury. [riumplus] loves Myst, and after 6 long years he’s finally completed his homage to his favorite game. It’s a replica of the in-game Myst book that is able to play every game in the Myst-iverse.

The build started off by searching for the same book used as a model for the book object in Myst. It’s a 135-year-old edition of Harper’s New Monthly Magazine, Volume LIV, Issue 312 from 1877. In keeping with the in-game assets, [riumplus] made dies for the spine and cover, embossed the word ‘MYST’ on the book, and filled these letters with 24-carat gold paint.

Inside the newly hollowed-out book [rium] added a very small x86 motherboard running Windows XP on a 32 Gig Compact Flash card. This tiny computer is able to run every Myst game ever made on a very nice touchscreen display.

It’s a work of art in our humble opinion, and a fitting tribute to the last great hurrah of the adventure game genre. After the break you can see [rium] interacting with his book, or just check out the build pics on [rium]’s Google+ page.

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DIY Pick And Place Builds Boards, Is Awesome

October 29, 2012 by Brian Benchoff 12 Comments

In what can probably be attributed to the pains of placing a lot of SMD components, [gravelrash] built his own home-made pick and place machine.

Instead of being frustrated with tweezers, stereo microscopes, and having an inordinate amount of concentration, [gravelrash] built a pick and place machine from a Chinese CNC router. The build doesn’t use automated feeders for its reels of parts. Instead,[gravelrash] picked up five manual feeders from eBay, allowing his pick and place to hold 25 different reels of components.

There is, of course, a vacuum pump for sucking up SMD parts and a two-axis gantry capable of moving components from reel to board. The software is Mach3, a program normally used with spinning cutters to mill away wood, metal and plastic. [gravelrash] replaced this motor with a few vacuum controlled needles to pick up, move, and drop components onto the board.

While the build may not be as fast as some other pick and place machines we’ve seen, it’s almost as fast as hand-placing components with the added bonus of not tearing your hair out over very tiny parts.

Tip ‘o the hat to [Alexander] for sending this one in.

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Bora Board Teaches Binary Hardware

October 29, 2012 by Brian Benchoff 7 Comments

If you’re just starting out in your quest to build really cool electronic devices, you’ll find a ton of options ready for the beginner. The Arduino makes toggling pins dead simple, and the Raspi brings the wonders of blinking a LED from the command line down from the gods and into the hands of the common man. These are all software platforms, though, and if you want to learn digital logic with hardware the best option is still a drawer full of 7400-series logic chips.

[Colin O’Flynn] hopes to change this with a beginners board for digital logic hardware design. It’s called the BORA, or Binary explORer boArd, and brings digital logic to a convenient package that is far less frustrating than a breadboard full of logic chips.

The BORA is based around a CPLD – a cousin of the FPGA-powered devices we see from time to time – that allows any student of digital logic to program the device and fill macrocells with NANDs, NORs, and ANDs.

The Xilinx device used in the BORA has about 1600 gates that can be programmed; more than enough to complete all the projects in the online lectures [Colin] has put together. You can check out the documentation for the BORA over on the official site, and the demo video after the break.

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OpenPLC, For Industrial Automation To Halloween Displays

October 27, 2012 by Brian Benchoff 27 Comments

Stepping out onto just about any factory floor you’ll find complex automatons building anything and everything imaginable. These machines need to be controlled somehow and before the age of computers these manufacturing robots were controlled with relays wired together to produce a multitude of actions. Relays, no matter how reliable and bulletproof the are, can’t be programmed without rewiring the entire machine. Now, factories have programmable logic controllers to take care of their automation tasks.

[Thiago] built his own programmable logic controller and released it as open hardware.Included in the OpenPLC are four 24V inputs, four 24V outputs (two with PWM), 0-10V analog inputs, and USB, SPI, and I2C for programming and expansion.

If you’re building anything from an industrial machine in your garage, or simply want really awesome Halloween (or Christmas) decorations, the OpenPLC can take care of driving all the solenoids, motors, and actuators needed. With the extendable I2C and SPI busses, it’s possible to add a plethora of sensors to bring a project to life.

The OpenPLC is based on an ATMega328 and is compatible with Arduino code. There are a few extension boards for digital and analog IO, as well as Ethernet.