Wireless Base Station Eavesdrops On Robot Communications

March 18, 2013 by 6 Comments

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The good [Doctor Iguana] has been working on a pair of robots which communicate with each other using mRF24J40MA wireless transceivers. This presents a challenge in debugging, as he really didn’t have an easy way of monitoring those communications. His solution was to build his own base station which lets him use a computer to monitor what each robot is saying.

He spun his own board for the project. USB connectivity is provided by an FTDI chip, the FT232RL. This converts the USB communications in to serial for the dsPIC33 microcontroller. The FTDI chip comes with a fairly fine-pitch, but the footprint can still be fabricated using toner transfer if you’re fairly familiar with the process. [Dr. Iguana] took some close-up images of the unpopulated board which might make you a little nervous with the soldering iron. The other end of the board hosts the same Microchip wireless module as he used in his robots.

After a bit of rework (noted on the photo labels) he got this up and running. Now he can capture all of the wireless communications and see if problems are due to the sender or the receiver.

Hack Removes Firmware Crippling From NVIDIA Graphics Card

March 18, 2013 by 135 Comments

If hardware manufacturers want to keep their firmware crippling a secret, perhaps they shouldn’t mess with Linux users? We figure if you’re using Linux you’re quite a bit more likely than the average Windows user to crack something open and see what’s hidden inside. And so we get to the story of how [Gnif] figured out that the NVIDIA GTX690 can be hacked to perform like the Quadro K5000. The thing is, the latter costs nearly $800 more than the former!

[Gnif] wanted the card for gaming and to support multiple monitors. It has no problem driving up to three screens under Windows. But the Linux drivers only allow this on the professional counterpart to the GTX690, the Quadro K5000. It turns out that the card responds to a device ID as assigned by a series of analog values. These can be tweaked by swapping, yanking, or adding resistors in just the right places. As with that Agilent multimeter unlock of his which we saw a few days ago, he somehow managed to figure out the secret sauce that unlocks the power hidden in this card.

Heat Your House With Propane (but Not In The Way You’re Thinking)

March 18, 2013 by 87 Comments

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[Ralph Doncaster] has a geothermal heat pump which is responsible for providing heat for his home. He’s been looking into some hacks that would make it more efficient and decided that the freon (R-22) needed to be tweaked. Some would say the stuff is bad for the environment, so he decided to go a different route. He replaced the Freon with propane, using this rig to make the fuel-grade propane more like cooling-grade propane called r-290.

He purchased the gauge set which is used whenever a technician services an A/C system (but you can also see it in this other A/C propane hack). That’s important because it’s responsible for making sure the old coolant is recaptured (his hose failure nixed this part of the plan) and the new coolant goes where it should at the correct pressure. But before dumping in propane from the local hardware store he needs to dry it out. Fuel-grade propane can have moisture in it, which can be bad for the cooling system. He bought a drier device, the grey bulb seen above, and soldered it on one end to a propane torch fitting and to a valve connection on the other. Now he could remove moisture as he pressurized the system.

Everything is working again, and the cooling side of the system gets much colder. He plans to do more testing as time goes by.

Google Glass Hack For Apple Fanboys Can Be Had Right Now

March 17, 2013 by 27 Comments

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If you’re a follower of Apple hardware the upcoming Google Glass release probably doesn’t interest you much. But the concept is universally cool. If you want to have your own one-eyed voice-activated computer running iOS, then this is the hack for you. [John] calls it the Beady-i, and posted a step-by-step article on how he put it together.

The headpiece is shown on the left. It’s a combination of a pair of glasses with projection screens built-in, and a gaming headset. [John] cut off one of the lenses, and removed the remaining arm of the glasses. That arm was replaced with the frame of a gaming headset, which now wraps around the back of his neck to make sure the lopsided display isn’t going to fall off.

By combining the electronics from both the glasses and the headset, and terminating the connections with a docking plug he’s got what he was after. The lens displays what is shown on the screen, and the gaming headset lets him hear the device’s sound in one ear and register input using the microphone.

Custom Boards At Home Without Etching

March 17, 2013 by 39 Comments

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PC board houses are getting more accessable and less expensive all the time. Some of us are even getting very, very good at making our own circuit boards at home. There are times, though, when a project or prototype requires an extremely cheap custom board right now, something etching a custom board won’t allow. [KopfKopfKopfAffe] has a unique solution to this problem, able to create custom boards in under an hour without any nasty chemicals.

Instead of starting his build with copper-clad board, [KopfAffe] used every rapid prototyper’s friend, simple one-sided perf board. The shape of the board was milled out on a CNC machine, and both the top silk screen and bottom layer were marked off using the toner transfer method. After that, a custom circuit is just a matter of placing components and putting solder bridges between all the marked pads.

[KopfAffe] is only using this technique for single-sided boards, but we don’t see any reason why it couldn’t be employed for simple double-sided boards. This would still have the problem of making vias between the layers, but that’s still a problem with proper, home-etched double sided boards.

Auto Off For Any Circuit

March 17, 2013 by 54 Comments

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Properly configured, your computer will go into sleep mode when left unattended for a long enough time. So will your cell phone, and just about every other piece of sufficiently complex electronics. Much simpler circuits, though, are left at the mercy of a SPST switch; if you forget to turn a flashlight off, it will be dead next time you need to use it. Wanting an auto-off circuit simple electronics, [Kyle] threw together this auto shutoff circuit.

The basic idea behind the cirucuit is to use a microcontroller as a timer controlling two transistors. When [Kyle]’s circuit is power cycled, the timer inside an AVR starts, making a pin high, and when the timer is up, making the pin low again. This pin feeds into a PNP transistor which is in turn connected to a NPN transistor, creating a very tiny auto off circuit for anything with an SPST switch.

[Kyle] says there are a few improvements to be made – using MOSFETS to handle higher currents and possibly using a smaller microntroller like an ATtiny 4/5/9/10 to shrink the circuit’s volume. It’s a great idea, bringing the idea of a flashlight with auto shutoff into reality.

Testing Caps With A DIY ESR Meter

March 16, 2013 by 21 Comments

There’s a problem with collecting old tube amps and vintage electronics – eventually the capacitors in these machines will die. It’s not an issue of a capacitor plague that causes new electronics to die after a few years; with time, just about every capacitor will dry out, rendering antique electronics defective. The solution to getting old gear up and running is replacing the capacitors, but how do you know which ones are good and which are bad? With [Paulo]’s DIY ESR meter, of course.

An ideal capacitor has a zero equivalent series resistance, and failure of a capacitor can be seen as an increase in its ESR. Commercial ESR meters are relatively cheap, but [Paulo] was able to build one out of a 555 chip, a small transformer, and a few other miscellaneous components.

The entire circuit is built on stripboard, and if you’re lucky enough to find the right parts in your random parts bin, you should be able to build this ESR meter with components just laying around.