I keep my tunes in an ammo can

ammo-can-boombox

Calling this a boom box is at least slightly ironic. Instead of high explosives it now carries high decibels in its new life as a self-contained sound system.

Despite the conspicuous power cord a peek inside reveals a big enough battery to keep the tunes playing for hours on end. [King Rootintootin] kept the cost on the build down since he was given the used speakers and amp by his girlfriend’s dad. The amp kicks out about 25 Watts with the battery rated at 7.2 Ah. He added a charger and routed the controls to the side of the ammo box so that it can be charged without removal. The only external component is the audio jack which connects it to the music source.

One of the suggested improvements from the Reddit thread is to add baffles inside of the enclosure so that sound from the two stereo channels doesn’t interfere with each other.

Soldering Small Components for a Video DA

Video DA Board

Video distribution amplifiers are used to amplify a video signal and split it into multiple outputs so multiple displays can be driven. They are also used to correct the gain of an incoming video signal. [Andrew] was having trouble with the video signal from an interferometer, and found the issue was caused by a low output gain. His solution was to build his own video distribution amplifier.

The THS7374 appeared to be the perfect chip for this application. It’s a four channel video amplifier IC, and only requires a few passive components to run. The only problem was the package: a 14 pin TSSOP with 0.65 mm pitch. Not fun to solder by hand, especially if you don’t have a PCB.

[Andrew]‘s solution was to build his own breakout out of copper-clad board. He worked under a microscope and cut out a pattern for the part, then soldered 30 AWG wire to the pins to make connections. After cleaning off any copper that could cause a short, the board was working, and the video waveform looked great on an oscilloscope.

After testing, even more gain was needed. [Andrew] ended up cascading two of the amplifiers. This method of prototyping doesn’t look easy, but could be worth it when you need a single board.

Adding AirPlay to a shelf system

adding-airplay-to-a-shelf-system

AirPlay is a great system. It allows you to send whatever media is playing from one device to another. Sure, we wish it were a bit more open (Apple is certainly not known for that) but there are several option for creating your own AirPlay receivers. After coming across a project that does just that, [Matt Shirley] decided to turn his shelf system into an AirPlay receiver.

The path to his goal depends on the Raspberry Pi’s ability to receive AirPlay audio using the Shairport package (we just looked in on another player that does this last week). He uses an Edirol UA-5 USB audio interface as an amplifier for his record player. He wasn’t using the USB port for it and knew that it would be simple to connect the RPi USB as a host for the device.

Wanting to keep the look of the system as clean as possible he popped the lid off of the amp. There is just enough room to fit the small RPi board inside. He hacked (literally, look at the pictures) an opening for the USB ports into the side of the metal enclosure. A short patch cable connects from one port to the USB jack on the back of the amplifier. The white cable leaving the side of the case provides power to the Rasperry Pi. The surgery was a success and now he can listen to his tunes with a tap of his finger.

An amplifier circuit good enough to eat

Gingerbread-Amplifier-009

[Dino's] kitchen skills match his hardware hacking prowess. Look really close at the image above and you’ll realize this collection of transistors and passive components is edible. Rather than decorating cookies for the holidays he built this audio amplifier from gingerbread, icing, and candy.

The thing is, [Dino] almost always has that extra touch to his presentations. If you watch the video after the break you’ll notice that the sound is not the crystal clear quality we’re used to hearing in his video. That’s because he used the hardware from which the edible offering was modeled to do the audio for the presentation clip.

After laying out the design using Express PCB he gets down to business. The base, which is gingerbread, looks just like a square of Radio Shack protoboard. To make the diodes he rolled up some tin foil around a screw driver to use as a mold for sugar and water which had been boiled long enough to give a dark color. A similar technique was used to cast the other parts. Everything was tied together using frosting and pieces of red and black licorice.

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Frankenstein, an all-tube home theater amplifier

amp

Here’s an exercise in excess if we’ve ever seen one. While working on his undergrad at Michigan State, [Gregory] thought it would be a great idea to build an all-tube home theater system. He calls his seven-foot tall rack of amplifiers ‘Frankenstein,’ and we’ve got to agree this build is an impressive monstrosity of engineering prowess.

[Gregory]‘s Frankenstein is a complete 5.1 home theater system. In the interests of sanity, the majority of the equipment in the rack is off-the-shelf gear including a CD player, surround sound processor, and a beautiful McIntosh solid state preamp. The power amps, though, are where this build really shines.

For the sub, [Gregory] built a wonderful monoblock tube amp, able to push nearly 300 watts into a subwoofer. The other channels for this home theater system are amplified with a huge four channel tube amp providing 480 watts per channel. In total, there are 23 tubes in [Gregory]‘s amplifier system, enough to consume 20 amps of filament current.

You can check out [Gregory]‘s demo video of his system after the break.

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Cute little amplifier has a tube pre

tube

While you won’t catch us in an argument with an audiophile regarding the sound quality of tube vs. solid state amps, there is a general consensus that tube amplifiers sound much better than their transistorized brethren. Actually building an all-tube amplifier, though, is a bit harder than one built around common ICs – there are transformers to deal with and of course very high voltages. One solution to get the sound of tubes easily but still retaining the simplicity of integrated circuits is a hybrid amp, or a tube preamplifier combined with a solid state power section. They’re easy enough to build as [Danilo] shows us with his hybrid tube amp design (Italian, translation).

[Danilo]‘s design uses two ECC86 for the left and right channels powered by a 12 Volt supply. Each channel is sent through a tube and then amplified by a TDA2005 20 Watt power amplifier. After plugging in a CD player, the result is a clear, warm sound that can put a whole lot of power through a speaker.

A pair of briefcase boombox builds

Here are two different briefcase speaker projects. [Dale] built the offering on the right back in high school and the upgraded version 2.0 more recently. He was inspired to send in a tip for the projects after seeing yesterday’s suitcase full of tunes.

The first version uses a pair of speakers pulled out of a car at the junkyard. They’re mounted on some particle board which beefs up the side of the plastic briefcase. The amplifier that drives it is mounted inside the case along with a battery to power the system. [Dale] included a crude storage bracket for the input cable and since the amp can drive four speakers there are connectors on the outside for two more.

Version two has quite a bit more polish. He doesn’t show that one off quite as much, but you can see there is a LED strip on the case that serves as a VU meter, as well as a numeric display which might be battery voltage? He mentions that this blows away any commercially available systems his coworkers have brought to the job site.

Video of both rigs can be found after the break.

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