Raspberry Pi controlled tank goes deeper than you might think

This remote control tank now takes its orders from a Raspberry Pi board. Well, actually it’s taking orders from commands pushed to the RPi board via SSH. The control scheme works out quite well. Using a low-profile WiFi dongle the RPi automatically connects to the wireless network when it is powered on. This makes it a snap to SSH into the device, and a more user-friendly controller will put a nice front-end into play at some time in the future.

But the real meat and potatoes of the hack comes in getting the RPi to talk to the tank’s circuitry. Just getting the Heng Long Tiger I remote control tank apart proved to be a ton of work as the treads need to be removed to do so and there’s a lot of screws holding it together. Instead of just replacing all of the control circuitry [Ian] wanted to patch into the original controller. To do so he spent a bit of time analyzing the signals with an oscilloscope and discovered that commands were coming in a Manchester encoded format. He established what various packets were doing, used a transistor to protect the GPIO pin on his board, and now has full control of the Tank. The final part of the hardware alteration was to power the RPi from the Tank’s battery.

After the break you can catch a demo of the reassembled tank sporting its new wireless controller.

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Computer desk… literally

This piece of furniture begs the question, why think of a desk and a computer case as separate things? It combines Ikea furniture with electronic hardware to create the ultimate command center.

First the obvious parts: there’s a nook for the computer case that hangs just below the desktop off to the side, and the twin displays are mounted front and center. The divider between the cabinet pieces was cut away to allow the monitors to be wall-mounted. But things start to get interesting to the left of those monitors. You can see a series of dial displays in the door for that cabinet. Those meters were sourced from the MIT Flea Market and after a bit of alteration they display CPU load information fed to them by  an Arduino board. This also drives some LED strips which are mounted behind the frosted glass panel that we guess could be called a back splash. The heavier the load, the better the light show.

All of the power management is taken care of in the cabinet to the right of the monitors. The top row hides a printer, external hard drive backup system, and several gaming consoles. Heat will be an issue so exhaust fans were added to each of these partitions. They’re switched based on a temperature sensor in each. It’s a lot of work, but the outcome proves it was worth it.

[via Reddit]

Raspberry Pi power regulator transplant reduces power consumption

If you want to run your Raspberry Pi from something other than a mains power converter, and you’ve got some courage to spare, this hack is right up your alley. [Tom] wrote in with a switch mode power replacement for the RPi’s stock linear regulator. This is the first hack we’ve seen where the RPi’s on-board hardware is being altered and that’s where things get a little scary.

The first thing done was to remove the linear regulator, leaving the unpopulated RG2 footprint seen above. Apparently a rework station wasn’t available as the technique they used describes holding the board up by gripping the regulator with tweezers, then blasting it with a hot air gun. It makes us a bit queasy because the processor chip has a solder footprint you don’t want to mess with.

But apparently all is still well. With the wasteful linear regulator gone a pair of 5v and 3.3V switch regulators inject voltage through the GPIO header. Initial tests show a savings of around 25% but we’d imaging this varies greatly based on load.

Under-bench timed outlets won’t let you leave the iron on

When we used to use firesticks (the pen style plug-in soldering irons) it was always a worry that we might leave them on. But now we use a base unit which has an indicator light to serve as a reminder. Still, [FoxxTexx] isn’t taking any chances and instead built this timer-based outlet which kills the power automatically.

The parts are all pretty common. The timer itself is the same form factor as a light switch and is commonly used for heat lamps or hot tub jets. It feeds the outlet next to it by way of the indicator switches to the right. We like the use of the switches but since mains voltage is still running through them we would suggest using a three-gang box and mounting them on the cover plate so that all the wiring is contained. If done this way you could just have the electrical box siting on your bench, but it is a nice touch to have it mounted this way.

We’ve long been proponents of a timer system. Back when we put together our Hacker’s Soldering Station we just used a plug-in timer unit.

Robot dares you to snatch the pebble from this flower

This pleasant-looking plant may try to take your hand off if you’re not careful. The robot flower (translated) includes sensors that cause the petals to move in reaction to external stimuli.

You can just make out the distance sensors as black rectangles on two of the petals. These let the flower track an object by rotating the flower stem. But if they determine the object is getting a bit too close for comfort, the servo motor on the back of each petal will cause the flower to suddenly clamp shut.

The video after the break starts off with an in-depth look at the hardware that went into the project. An Arduino clone called the GRoboduino makes this project a lot easier since it has a bunch of extras on the board aimed at things like sensors and servo motors. The mounting technique for the petal-powering-servos is quite attractive, and we enjoy the Snapple lid (probably not the actual brand but you get the picture) which has been coated with yellow felt for the center of the bloom. The final look is normal enough to fit in with home decor, but it still has enough geek in it to melt our hacker hearts.

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Testing Lithium cells for use with a hybrid car

[Mikey] got a real deal on some A123 Pouch Cells. These are large Lithium cells that tolerate 100A discharge and 50A recharge currents, with 20 AH of life off of one charge. He’s been doing a bunch of testing to find out if the cells can go into an expandable battery pack and be made for use with hybrid cars.

We just looked in on a battery tester used for solar power car arrays. This is a similar situation except [Mikey] is focusing on the test data, rather than the apparatus. The link above is a collection of his notes from testing. Start reading at the bottom of the page up to get the chronology right. He starts to zero in on the most efficient charging methods. Immediately he’s hit with a big need for cooling as the cells take no time to pass 100 degree Fahrenheit. He continues testing with heat sink and fan, and even brings a thermal imaging camera to help with the design.

[Thanks Chris]

A guide for laying out 4+ layer PCBs

Learning to lay out a printed circuit board takes some time. But after you’ve churned out a few it’s really pretty easy. If you find yourself at that point it may be time to learn about more complicated board fabrication. We think a good primer is this multi-layer PCB layout guide which [Rik te Winkel] recently put together. It’s one of the results of his internship experience.

One of the major differences with boards that have more than two layers is the ability to alter what layers are actually connected by vias. Vias are plated holes through the substrate that connect different layers of copper. In the case of a 2-layer board these just go right through and connect the top to the bottom. But as you can see above, there are additional choices when it comes to multi-layer boards. #1 is a through via connecting all of the layers. #2 is a blind via; it stops part way through the board. And #3 is a buried via; it connects internal layers but cannot be seen from either side.

The guide is aimed at Eagle CAD. To use more than two layers you’ll have to purchase a license. But we think the concepts can easily be translated to other PCB layout software like Kicad.