Automatic Speaker Control Via TV

August 15, 2012 by Mike Szczys 5 Comments

[Jon] wanted his speakers to come on and off along with his TV. The speaker heats up if left on so he didn’t want to do that. But killing the power also resets the volume level (this is an old set of PC speakers and the remote is wired, not IR) so using one of those switched power strips was out as well. He thought a bit about trying to use the power LED on the TV to build his own circuit when it dawned on him. It’s possible to monitor the USB port on the TV and use it to switch on the speakers.

The circuit above uses a couple of opto-isolators to protect both the television and the speakers. The 5V line from the USB port on the back of the TV is monitored by an XNOR gate (which helps to filter out some of the toggling at power-on). When that gate latches it activates a 555 timer which in turn fires up the speakers. Presumable this happens when power is cut as well, but we’ll let you work through the circuit logic yourself.

How Not To Dim EL Panels, TRIACs!

August 10, 2012 by Jesse Congdon 15 Comments

We’ve all been there: an exciting brilliant idea, scratched onto a napkin, hastily plugged into a breadboard, all for naught. Even the best ideas sometimes suffer from a heavy dose of reality. [Ch00f] over at ch00ftech recently had a similar experience dimming an EL panel of his using a TRIAC and some clever waveform manipulation. Instead of tossing the parts ~~across the room in a fit~~ aside and moving on he goes into a detailed analysis of what went wrong.

This method differs from the way most EL drivers dim output loads, instead of chopping the output like a PWM controlled LED the TRIAC snips the ends of the waveform and makes an ugly but less powerful output. The issue with this method is that when you cut the waveform during non-zero crossings it causes massive current spikes. These can wreak havoc on a cheap EL inverter and generally cause headaches all around. [Ch00f ] speculates that his woes may be due to the fact that EL wire is a capacitive load, causing voltage to fall out of phase with the current. This is one of those engineering problems with a thousand and one answers, we can’t wait to see what he comes up with.

Check out the writeup for all the “deets” (as [ch00f] would say) as it is a pretty good primer on TRIAC operation. If there isn’t enough glowy wire in this post you can also check out this sound reactive panel or an informative guide on EL or even more from [ch00f] in general.

MythTV Library On Apple TV Without A Jailbreak

August 2, 2012 by Mike Szczys 16 Comments

[Dan] wrote in to share a link to his MythTv to Apple TV setup. He found a way to make the recordings he made on his Linux box available on the 2nd Generation Apple TV. Our first thought is that he would use XBMC on a jailbroken device but that is not the case. The secret is to roll iTunes into the mix.

Take a look at the diagram above. The system starts with an Arch Linux box that runs MythTV, an open source program which allows you to record from tuner or encoder hardware. But actually watching those recordings on an iOS device is difficult for a couple of reasons. First, Apple likes to keep their devices locked up tight in hopes that you buy your entertainment rather than watching over-the-air records. Second, if you’re recording ATSC channels the files may be 1080i or 1080p, neither of which can be handled by the Apple TV 2. [Dan] gets around this by first using the command line version of Handbrake to transcode the recordings to an h264 format. He then uses iTunes running on an Windows 7 virtual machine (on the Linux box) to host the transcoded files in a library the Apple TV can access.

Digital TV Converter Reverse Engineering

August 1, 2012 by Mike Szczys 15 Comments

Back when broadcast television was first switching over from analog to digital most people needed to get a converter box to watch DTV broadcasts. Remember that abomination that was “HD-Ready”? Those TVs could display an HD signal, but didn’t actually have a digital tuner in them. Nowadays all TVs come with one, so [Craig] found his old converter box was just gathering dust. So he cracked it open and reverse engineered how the DTV hardware works.

The hardware includes a Thompson TV tuner, IR receiver for the remote control, and the supporting components for an LGDT1111 SoC. This is an LG chip and after a little searching [Craig] got his hands on a block diagram that gave him a starting place for his exploration. The maker of the converter box was also nice enough to include a pin header for the UART. It’s populated and even has the pins labeled on the silk screen. We wish all hardware producers could be so kind. He proceeds to pull all the information he can through the terminal. This includes a dump of the bootloader, readout of the IR codes, and much more.

Diablo 3 Is An Arcade Game, Apparently

July 26, 2012 by Brian Benchoff 7 Comments

MAME cabinets are simply awesome. They’re a great way to relive the stained and sticky fluorescent carpets, loud noises, and Neon signs and blacklights of old arcades. If there’s one problem with MAME cabinets, it’s that gaming has moved on from the quarter-eating cabinets of yesteryear. It simply doesn’t make sense to put Starcraft, TF2, or other popular games in an arcade cabinet.

[Dave] grew up playing Gauntlet in the arcade, but the various console ports never lived up to the experience of playing it with a joystick and buttons. When Diablo 3 came out, [Dave] knew what he had to do. He built a Diablo 3 arcade cabinet, fully playable and faithful to the dungeon crawlers of yore.

Thankfully, an old cabinet wasn’t gutted for this build; a month before the game came out, [Dave] picked up a few pieces of plywood and built himself an arcade cabinet. After applying some very nice graphics and installing buttons and a joystick, [Dave] had a fully functional Diablo arcade game that doesn’t even require quarters.

Recently, we’ve seen our share of builds that turn traditional game controls on their head, a trend we hope continues. You can check out [Dave]’s demo video after the break.

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One Remote To Stream Them All

July 24, 2012 by Mike Szczys 11 Comments

We’d bet that most readers stream video as the lion’s share of their entertainment consumption. It’s getting easier and easier thanks to great platforms like XBMC, but not everything is available in one place, which can be a bit off-putting. [Tony Hoang] is trying to simplify his viewing experience by creating one remote to rule all of his streaming software. He’s got an HTPC connected to his entertainment center, and used a bit of scripting to add some functionality to this Lenovo N9502 remote control.

The hack is entirely software-side. The remote already works quite well, but he remapped the home, end, and page up buttons, as well as the mouse controller. The three buttons will launch XBMC, Hulu, and Netflix respectively. They are also set to kill the other applications before launch so that one button will do everything needed to switch between one another. The mouse remapping takes care of up, down, left, and right keys for navigation in the UI and control of the playing videos. See a demo of the setup after the break.

Everything was done with autohotkey scripts for Windows. But this should be easy to code with other OSes as well. If you’re prone to have a slip of the finger you might want to work out a double-click to launch the applications so you don’t accidentally hit a key in the middle of your favorite show.

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Create A Laminar Flow Jet Without Pesky Fiber Optics.

July 24, 2012 by Jesse Congdon 15 Comments

[ApexLogic] had some PMMA core acrylic rod rod left over from a project and decided to use it as the lighting element in a laminar flow water jet.

The typical water jet consists of a bunch of sponges and drinking straws sandwiched together to slow a rough water stream and then a finely cut nozzle to provide a smooth ripple-free strand of clear water. If light is applied to this stream of water it tends to act similarly to fiber optics. [ApexLogic], however, uses a combination of shaved PVC filings, Brillo, and what appears to be most of the plumbing aisle of a local hardware store to get the same laminar flow. To top it off the polished acrylic rod is much less fragile than its glass-fiber counterpart and can have a high power light glued to the end for a nice water tight seal.

The system currently runs off of garden hose pressure, and would probably need some kind of a boost before it went into that front yard mega fountain that [Caleb] is still waiting for somebody to make. If you still need some clarity on laminar water jets check out these videos on a few