UPDATE: Roll your own GPS can now track twice as many satellites


[Andrew Holme] wrote in to tell us about some work he’s done to improve his scratch-built GPS receiver. He figured out a way to use the same hardware but double the number of satellites it can track to a total of eight. When we looked at the original hardware about a year ago it was limited to monitoring just four satellites. That’s the bare minimum for calculating position data. This will not only help increase the accuracy, but remove the problems that would have been cause if just one satellite was dropped because of an obstruction or other issue.

His solution is based entirely on using the FPGA in a different way. He had taken up almost all of the gates available in the Xilinx Spartan 3 chip. Now he’s implemented a CPU on the chip and is able take some of the work off of the hardware gate design by running code on it. He also found and squashed a bug in how the data was processed. He says his original work wasn’t taking into account the rotation of the earth when determining position. All of these improvements put his accuracy at +/- five meters even when he’s not tracking all eight satellites!

How to write your own Minesweeper solver


We think we have found project that will take over our holiday free time. [Bai Li] just published an excellent article about writing a program that can automatically solve the game of Minesweeper. For those of you who are unfamiliar, Minesweeper gives you a grid in which land mines have been randomly placed. As you click on boxes to reveal what is underneath you are greeted with a number which represents how many mines surround that box. [Bai's] project examines how the puzzle may be solved programmatically.

He chose to use Java to write the solver. This works well both reading from the screen as well as simulating mouse clicks on the game. The reading portion of the program uses color detection with a screenshot. There were two problems associated with this, the numeral one is almost the same color as an uncovered square, and the numerals seven and three use identical colors. The input portion was much simpler as he’s able to use the existing Robot class.

The logic behind writing an efficient solver is very interesting. One of the most fascinating examples is shown above. What should you do when there is no possible way to ensure a safe move? As with traditional chess games, [Bai] has the solver calculate all possible solutions and choose the move that has the best odds of success.

His source code is available, but won’t this one be fun to hack out from the concepts alone? For some reason this seems more accessible to us than something like the Bejeweled Blitz solver.

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Robot can barely move with so much hardware strapped to it


We think that [Andrej Škraba] needs to start looking for a beefier motor platform. This little robot has so much hardware strapped to it the motors can barely keep up. But with a little help it can make its way around the house, and it takes a whole lot of connectivity and computing power along for the ride.

The white stick on the top is a single-board computer. The MK802 Mini sports an A10 processor and up to a gig of ram. Just below that is a USB hub which is sitting on top of a USB battery pack. This powers the computer and gives him the ability to plug in more than one USB device. The robot chassis is from Pololu. It uses an Arduino and a motor shield for locomotion, with commands pushed to it via USB.

This setup makes programming very easy. Here [Andrej] has a keyboard and HDMI monitor plugged in to do a little work. When not coding it can be disconnected and driven over the network. He makes this happen using an Apache server on the MK802 and node.js. See a demo of the system in the clip after the break.

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A concrete table with a little blinky built in


Members of the Warp Zone hackerspace wanted a coffee table that was beyond ordinary. They ended up pouring a concrete base for the glass top (translated). There were several things to address during the design. First off, they wanted to integrate LEDs in the concrete sides. Some consideration had to be made for portability as concrete is very heavy. The final piece of the puzzle was deciding what kind of hardware to place beneath the frosted glass.

The legs were designed with a large cut-out area to keep them as light weight as possible. The cross piece has a set of voids spelling out the name of the hackerspace with some green LEDs. This was accomplished by placing foam cut-outs of each letter in the forms before for concrete was poured. They sealed around each letter with silicone, but still had some seepage most likely caused when jostling the form to help remove air bubbles. Straws were placed in the foam to allow a cable pass through for the electronics. After everything was in place they filled the voids with hot glue to act as a diffuser.

There aren’t a lot of details about the RGB LEDs under the frosted glass. But you can see the light show they produce in the clip after the break.

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Olin College Penny Press

Olin Penny Press

Inspired by souvenir penny presses, [Robert] built the Olin College penny press. This machine stamps out coins with the school’s name and a variety of other patterns. He built it as part of a mechanical structures course, with the goal of designing something that used large forces.

Crushing a penny takes about five tons of force. To deliver that force, [Robert] used a 1 horsepower motor coupled to a custom 1190:1 reduction drive train, which consisted of sprockets, gears, and chains. The aluminium frame supporting the drive train also had to be designed to withstand large forces.

This required of a lot of custom parts, which were made using a CNC mill, a water jet cutter and a mill. All of the CAD drawings are available for anyone who wants to replicate the design.

This beast of a machine weighs about 90 pounds and can squish 12 pennies every minute. Olin College installed the penny press on their campus for anyone to use for free.

Hackaday Links: Christmas Eve, 2012

It’s Christmas Eve, the perfect time to interact with your extended familial units, eat cookies, nog things up a little, and watch Die Hard. Christmas Eve also means it’s a low-effort day here at Hackaday, so here’s a few cool things we’ve run across in the past few weeks.

A Round OLED Display


That right there is a circular OLED display. [ArtistEngineer] over on reddit found this display on AliBaba. It’s a 1.13 inch diameter display with a resolution of 128×128 (yeah, we don’t know either). This looks like a great display for a DIY wrist watch, digital gauge, or loads of other devices where a square display doesn’t make much sense.

There seems to be a few circular OLED display manufacturers – including Truly Semiconductors who happened to put up a datasheet for their round display - but sourcing these in reasonable quantities is a pain. Anyone up for a group buy? Think of the fun you’ll have coding a polar coordinate display!

Computing with transistors


So you know computers are made up of simple logic gates, latches, buffers, and other miscellaneous digital cruft,  but how do we turn these digital circuits into a computer? Over the last few months, [Andrew] has been putting up a bunch of blog posts on the application of digital logic. Start out on the ‘Computing with Transistors’ post before moving on to The Digital State and Circuits and Arithmetic. There’s some good readin’ there.

 Embedding 3D objects in a web page

Go ahead. Click it. It’s Sketchfab that allows anyone to publish interactive 3D designs without a browser plugin. If anyone out there is trying to build a Thingiverse clone that isn’t tied to Makerbot, consider using this for the preview page for each object.

Surprisingly, Twinkies were the one thing that didn’t survive the Apocalypse.


While there’s no use in mourning the death of the Twinkie – Little Debbie also makes small cream-filled cakes – you might as well include some Twinkies, Snowballs, Ding Dongs, and Ho-Hos in your Christmas baking. [scoochmaroo] on Instructables put together a list of homebrew recipes for the now defunct Hostess snack cakes.

Perfect for autonomous robots


[maxogden] over on the gits put together a script for automatically joining wireless networks on Linux. This was tested on a Raspberry Pi, and we’re thinking it would be perfect for whatever autonomous creation you’ll be building in your workshop next year.

Pulling the LCD screens out of a MyVu glasses display


[John Floren] really sells us on a pair of MyVu 301 Video Glasses. He lists the features as being bulky, ugly, and uncomfortable. That’s the reason why he’s showing you how to crack open the glasses in order to steal the tiny LCD modules.

The LCD screen for each eye is mounted inside of the assembly seen above. The screen is perpendicular to the wearer’s eye, with some space in the body to facilitate the lens and reflector that enlarge the image and direct it toward the eye. After removing the display from the module [John] tried to hook it up to a camera via the driver hardware which comes with the glasses. It must have been a bit of a head scratcher that all he could get was a plain white image. This is fixed by finding the polarizing filter inside the module and laying it over the screen. This is demonstrated in the clip after the break.

We don’t know where he’s planning to go from here, but we can suggest a few different projects. This hardware could be useful in creating his own augmented reality hat. Using it as a video game controller is another thing that pops to mind. Wouldn’t it be cool to have this in the scope sight of a light gun?

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