Kickstarting Router-Based Development Boards

[Squonk] is rather famous in the world of repurposed routers, having reverse engineered the TL-WR703N wireless router from TP-Link a few years ago. With that knowledge, he’s developed an open platform for Things on the Internet called Domino. It’s pretty much exactly what you would get by cracking open a router bought on AliBaba, only in a much more convenient package with many more pins broken out.

The Domino builds on [Squonk]’s reverse engineering efforts of the TP-Link TL-WR703N wireless router, the router that has stolen the thunder from the Linksys WRT54G for all those sweet, sweet, embedded hacks. Both the 703N and the Domino are built around the Atheros AR9331. While the router version of this chipset only breaks out a few GPIOs and other interesting pins, the Domino breaks out just about everything – GPIO, JTAG, I2S, UART, SPI, USB, and Ethernet can be found on the device.

The basic Domino can hopefully be had with a $25 pledge to the Kickstarter campaign. That’s a little less than the normal price for a WR-703N, and if you’re putting a router in a hat it might be worth your while. There are a few advanced versions that include an ATMega32u4 microcontroller, making it compatible with the Arduino Yun as well.

Retrotechtacular: Stateside Assembly And Launch Of V-2 Rockets

At the end of World War II, the United States engaged in Operation Paperclip to round up German V-2 rockets and their engineers. The destination for these rockets? White Sands Proving Grounds in the New Mexico desert, where they would be launched 100 miles above the Earth for the purpose of high altitude research.

This 1947 War Department Film Bulletin takes a look inside the activities at White Sands. Here, V-2 rockets are assembled from 98% German-made parts constructed before V-E day. The hull of each rocket is lined with glass wool insulation by men without masks. The alcohol and liquid oxygen tanks are connected together, and skins are fitted around them to keep fuel from leaking out. Once the hull is in place around the fuel tanks, the ends are packed with more glass wool. Now the rocket is ready for its propulsion unit.

In the course of operation, alcohol and liquid oxygen are pumped through a series of eighteen jets to the combustion chamber. The centrifugal fuel pump is powered by steam, which is generated separately by the reaction between hydrogen peroxide and sodium permanganate.

A series of antennas are affixed to the rocket’s fins. Instead of explosives, the warhead is packed with instruments to report on high altitude conditions. Prior to launch, the rocket’s tare weight is roughly five tons. It will be filled with nine tons of fuel once it is erected and unclamped.

At the launch site, a gantry crane is used to add the alcohol, the liquid oxygen, and the steam turbine fuels after the controls are wired up. The launch crew assembles in a blockhouse with a 27-foot-thick roof of reinforced concrete and runs through the protocol. Once the rocket has returned to Earth, they track down the pieces using radar, scouting planes, and jeeps to recover the instruments.

Thanks for the tip, [Thomas].

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.

diy power wagon

Snow Blower Turned Power Wagon

Winter is now gone and it’s time to put away that snowblower. Well, it seems that [SWNH] either didn’t hear the news or thought not using his snowblower for most of the year was a waste of a great resource. No, he’s not using it to blow dirt around, he converted it into a Power Wagon.

A Power Wagon is just what it sounds like, a wagon that is motorized and it is used for moving stuff around your yard. [SWNH] started by disassembling the 2 stages of the snowblower. They came off as a unit with only 6 bolts. Next up, the wagon bed was made, starting with an angle iron frame with a plywood bottom and sides. Two large casters with rubber wheels supports the front of the wagon.

Using the power wagon is easy, fill up the bin and use the snowblower controls to drive the cargo around. [SWNH] says that it steers like a shopping cart. And since the wagon bed is bolt-on, it can be removed and the blower assembly re-installed next winter to take care of that pesky snow.

Powerwheels Jeep

Powerwheels Racing Series In Detroit

[Transistor-Man] and the gang finally got around to documenting their experience at the Detroit Makerfaire 2014 and the Powerwheels racing series. They weren’t planning on entering, but in a last-minute decision they decided to see if they could whip up an entry just over one week before the competition! They did — and it’s awesome. They call it the Chibi-Atomic-Jeep.

As the competition name implies, they had to base the vehicle off of a Powerwheels frame. Bunch of steel tubing, some TIG welding and a nice paint job, and they had the base frame of their vehicle. At the heart of it? An alternator from a van — surprisingly powerful and easy to control. They used cheap 8″ wheels from Harbor Freight Tools — they worked great, just didn’t last very long… By the time the races were over, they went through NINE of these tires. Good thing they’re cheap!

The most impressive part of the build is the gears. They made them using a water-jet cutter at the local hobby shop and a Bridgeport mill with an indexing head — not an easy task to complete!

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Interactive Software To Solve Crosstalk Problems

A link to this video demonstrating PCB cross-talk ended up in my mailbox the other day as I tend to stay on the mailing lists of the some of the high end CAD companies. There are some really interesting and powerful “mega-tools” that do things like plot noise density for decoupling analysis and extremely high speed timing analysis, though the costs of these tools are commensurate with their capabilities. This one is part of the Mentor Graphics PCB Simulation software.

The tool shown does the math needed to predict the induced voltage noise (cross-talk) generated by the proximity of noise sources to the noise susceptible elements, and the tool does so interactively. This is remarkable… in the past we would calculate some examples of trace width, spacing, and the type of signals involved, and then generate some rules of thumb that we tried to apply during the layout process. It was an educated guess that was sometimes not as close as we would have liked.

Virtual Scope Showing Predicted Crosstalk
Virtual Scope Showing Predicted Cross-talk

 

The cool part of this software is the interactive nature. One can learn the effects of placement on cross-talk in real time, which helps build an intuitive understanding.

I will add the standard disclaimer that a tool is exactly that, a tool, and it only represents an approximation of real life at best. It’s tempting to design to the tool itself, and many engineers have learned the limitation of a tool the hard way. Instead think of the tool as another opinion, or as mentioned, a learning aid to gather an intuitive feel for the effects of placement on circuit performance.

circuit board

Driving A Brushless DC Motor Sloooooooowly

Driving a brushless DC (gimbal) motor can be a pain in the transistors. [Ignas] has written up a nice article not only explaining how to do just this with an Arduino, but also explaining a little bit on how the process works. He uses a L6234 Three Phase Motor Driver, but points out that there are other ways to interface the BLDC motor with the Arduino.

warningA warning is warranted – this is not for the faint of heart. You can easily destroy your microcontroller if you’re not careful. [Ignas] added several current limiting resistors and capacitors as advised in the application note (PDF warning) to keep things safe.

Everything worked well at high speeds, but for slower speeds the motor was choppy. [Ingus] solved this riddle by changing over to a sine wave to drive the motor. Instead of making the Arduino calculate the wave, he used a look up table.

Be sure to check out his blog for full source and schematics. There is also a video demonstrating just how slow he can make the motor move below.

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VCF East X: The World’s Largest USB Thumb Drive

The Vintage Computer Festival last weekend featured racks and racks of old minicomputers, enough terminals for an entire lab, and enough ancient storage devices to save a YouTube video. These storage devices – hard disks, tape readers, and 8″ disk drives – were only connected to vintage hardware, with one exception: a DEC RL02 drive connected to a modern laptop via USB.

The DEC RL02 drive is the closest you’re going to get to a modern mechanical hard drive with these old machines. It’s a huge rack unit with removable platters that can hold 10 Megabytes of storage. [Chris] found one of these old drives and because he wanted to get into FPGA development, decided to create a USB adapter for this huge, old drive.

The hardware isn’t too terribly complex, with a microcontroller and an FPGA that exposes the contents of the drive over USB mass storage. For anyone trying to bootstrap a PDP-11 or -8 system, [Chris] could download disk images from the Internet, write them to the disk, and load up the contents of the drive from the minicomputer. Now, he’s using it with SimH to have a physical drive for an emulated system, but the controller really doesn’t care about what format the disk pack is in. If [Chris] formatted a disk pack with a FAT file system, he would have the world’s largest and heaviest USB thumb drive in the world.

Video below.

Update: As promised, [Chris] put all the code in a git

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