How computers work, starting with transistor gates

[Andrew Gibiansky] has just started a tutorial series called Computing with Transistors. It’s purpose is to pull back the many veiled layers between high level languages and the controlling of electrons. And fittingly this first post starts off by explaining voltage source, load, and current. Don’t be thrown by its simplicity though. [Andrew] quickly moves on to talk about switching transistors and how they are used to build gates like the OR NOR gate seen above.

If this is the least bit interesting you should also look back at the post about Nand 2 Tetris. It’s an online course that works its way through The Elements of Computing Systems text book. We’ve been following that journey ourselves, having made it through the hardware build in about a week. The assembler took about the same amount of time, and right now we’re in debugging hell trying to get the last function call and return parts of the VM translator to work right. We’ve used most of the skills needed in this journey before, but never all in one project. It really has shed a lot of light on the gaps in our knowledge, and we’re having a lot of fun at the same time!

[via Reddit]

BeagleBone powers this networked LED marquee

[Mahmut] calls this project SmartBox. It’s a BeagleBone controlled LED marquee which can pull down information off of the Internet.

The project started with the display itself. [Mahmut] used six 5×7 LED modules to populate a circuit board he produced himself. The low side of the modules is controlled by some MBI5026 constant current drivers, with PNP transistors on the high side. The display connects to the BeagleBone ARM board using a couple of IDC ribbon cable connectors. With that up and running he started working on the enclosure. The display board was modeled in Google SketchUp to ensure that the case design would fit it properly. The laser cut acrylic case is in two parts, the base holds the driver electronics, with a hinged section for adjusting the angle of the marquee.

So far there are a few different connectivity features which are shown off in the clip after the break. The BeagleBone has the ability to pull down Twitter feeds, notify about incoming email, and scroll messages.

[Read more...]

Controlling Google TV from a Raspberry Pi (or other networked devices)

Google TV is a network connected television. It does what you would think: plays television programs, streams media from the internet, and allows you to open URLs on your TV. But one nice feature is that it can also be controlled over the network rather than just via an IR remote. Google publishes apps which make this simple with a smartphone. But the communications protocols are open source, so [Leon Nicholls] wrote a Google TV remote control library in Java.

The video after the break shows him pairing a Raspberry Pi with his television. The image above is the pairing verification code you must enter on the remote hardware before control is authorized. Apparently this is a step that needs to happen every time if using Google’s Anymote library. [Leon] improved that, by saving the pairing data so that the first authorization is all that it takes.

He figures this could be used for home automation. We’re not sure what we’d use it for but we’d love to hear your ideas in the comments.

One-button audiobook player made from a Raspberry Pi

[Michael Clemens] was looking for gifts for his Grandmother’s 90th Birthday. She is visually impaired and loves to be able to listen to audiobooks. The problem is that she doesn’t really get the hang of using electronics. He made things easy by building her a one-button audiobook player.

The Raspberry Pi board is a perfect solution for this project. It’s cheap, it has an audio port, it has storage for the books on the system SD card, and it runs Linux. The last part is key as it made things very simple when [Michael] started pulling together the various components.

When the RPi is powered up it drops immediately into a Python script which loads the audio track and places the music player daemon in pause. The yellow button seen above works as a play/pause button when clicked. If the listener misses something she can hold the button for more than four seconds to go back one track. Loading new books is easy too. [Michael] copies the files onto a thumb drive with a special volume label. When plugged into the RPi USB port the script automatically copies the book and starts playing when the drive is removed. He included a video demo on his project page linked above.

Hacking an old radar gun to interface with a laptop

[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.

[Read more...]

Playing video games on your office phone

So IT has your computer locked down, but if you’re lucky enough to have this model of telephone you can still play video games while at work. [AUTUIN] was at the thrift store and for just $8 he picked up an ACN videophone on which he’s now playing video games. We don’t know what magical second-hand stores sell functioning electronics of this caliber  but you should never pass up an opportunity like this.

It turns out the phone is running Linux natively. After some searching [AUTUIN] found that it is possible to telnet to a root shell on the device. Doing so he was able to figure out that the phone uses standard packages like ALSA for the Audio and /dev/input/event0 for the keypad. It even includes an SD card slot so he loaded one with a Debian image and used pivot_root to switch over to that OS. At this point the phone is his to command and of course he loaded up a video game which you can see in the clip after the break.

[Read more...]

Hackaday’s official Kickstarter policy

we don’t have one… yet.

We’re getting inundated with campaigns on crowdfunding sites like kickstarter and indiegogo. Sometimes they’re really cool projects, sometimes they’re not. Unfortunately, they are all basically appeals for coverage on hackaday so they can get money. That immediately puts a negative taste in our mouths. Then again, if a hacker legitimately makes something really awesome, why wouldn’t we want to help spread the word?

We don’t want to stop a really cool project from being shared with you just because it is on kickstarter, but we also don’t want to serve as a crowdfunding advertising platform. It ends up being complicated, especially if the idea is really cool, but the details are sparse.

So, what do you think? Share your thoughts on how hackaday should handle crowdfunding in projects.

p.s. This started as a rant about how sick of the constant pleas for kickstarter coverage we’re getting. We’re trying to stay positive and constructive here, please do the same in the comments.

 

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