Build a Simple Audio Amp

[Ynze] has built an audio amplifier that looks and sounds great. His amplifier uses a National Instruments (now TI) LM3886 Overture series 68 Watt power amp. The LM3886 places [Ynze's] amp squarely in the “Gainclone” catagory. Gainclone or Chipamp are terms long used by the DIY community to describe audio amps based upon highly integrated semiconductor amplifiers. The Gainclone name stems from the original Gaincard audio amplifier sold by 47 labs.

The Gaincard used less than $100 USD of parts when it was introduced in 1999. It sounded good enough to command a $3300 USD price tag on the audiophile market. The low parts count and simple construction spawned the audio DIY community to build their own versions of the Gaincard. Hundreds of variants exist now, and wading through the different versions can be a bit of a daunting task. [Ynze] found a basic design that works, and built from there.

One of the interesting things about [Ynze's] amp, as well as many of the Gainclones, is the fact that they use no circuit board. All wiring is done point to point. resistors are soldered directly to the pins of the amplifier chip. This can be some tricky soldering for beginners, but several PCB kits are available. [Ynze] built his amp in two cases. One case holds the power supply, and the other contains the amplifier itself. [Ynze] is using a large toroid transformer to drop his local 230V mains down to +25V and -25V. The amplifier circuit itself is simple – a few discrete components surround the LM3886 and it’s heat sink. [Ynze] also did some very nice carpentry work on his wood chassis. The resulting amp looks like it’s right out of the 1960′s – but hides 1990′s electronics inside.

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Un-crapifying a Car Stereo

[Noah Farrington] has just accomplished a major milestone in his life, purchasing his first car! A glorious 2001 Ford Focus wagon. While it may be a fully loaded luxury vehicle, it is missing one thing poor [Noah] can’t live without. An aux-in port. He had a few options for rectifying the situation. Live with it as is, hack the strange Ford media protocol out of the back, or fool the CD player into playing his input. Naturally he chose the third option.

His first challenge was removing the deck from the car. People told him he’d have to buy fancy stereo removal tools — he made do with tent pegs and coat hangers. Using the same method as described in a past aux-in hack, he identified the audio in leads on the CD player’s ribbon cable. By carefully soldering in his own aux-in plug, he’s almost ready for business! Unfortunately, the CD player also needs to think that it is on for it to properly output the audio. [Noah] chose the simple solution — record a silent CD to always leave in the deck. Stick around after the break to see it in action.

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Superb DIY Daft Punk Helmets

Learn how to create your own exceptional looking Daft Punk helmets using casting and molding techniques.  The project comes from a professional prop creator who shows you step by step how to create your own through a two part tutorial.  The overall detail and craftsmanship is absolutely superb.

As you can see through the project photos, the overall process seems pretty labor intensive with numerous sanding and molding stages.  Definitely worth it though, for the outstanding results.  If it’s too much work to build one, you can always buy a replica from the author.

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Ethernet Enabled Christmas Bells – Create a Tune in Real Time!

Here’s a superb project which allows you to create a Christmas jingle using a flash interface in your browser.  Then, you’re redirected to a webcam where you can see your tune played in real time!  Awesome!  The project uses the Arduino to handle the communication and bell control.  It’s dirt simple – you create different tones using letters on the keyboard and your your 20 seconds of musical wizardry is recorded and played back like a Christmas tune.

Create your Tune: 

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Sonar With Python and Conference Call Hardware

[Jason] just tipped us off about his recent experiment, in which he creates a sonar system using standard audio equipment and a custom Python program. In case some of our readers don’t already know it, Sonar is a technique that uses sound propagation to detect objects on or under the surface of the water.

It is commonly used in submarines and boats for navigation. [Jason]‘s project uses active sonar, which consists in sending short audio bursts (chirps) and listening for echoes. The longer it takes for the echo to return, the further the object is. Though his proof of concept is not used underwater, that may change if he continues the project.

The audio editing software Audacity was used to make a fast frequency changing chirp, along with PyAudio libraries for the main Python program. Exact time of arrival is detected by correlating the microphone output with the transmitted signal. Given that [Jason] uses audible frequencies, we think that the final result shown in the video embedded below is quite nice.

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Headphone Hack Makes Wireless an Option

If you have a favorite pair of over-the-ear headphones you may want to consider upgrading them with a wireless option. The key word here is “option” because these still retain their functionality as a wired headphone. This is nice if you only want to deal with battery life when you’re actually roaming around.

Of course the thing that makes this type of hack work is the extra room inside the body of the earpieces. [Tony] cracked them open and decided there was just enough room to fit the internals of a Bluetooth audio adapter. It has it’s own Li-ion battery (boasting 12 hours of use) which is why there is an added charging port. To fit the board he had to remove some of the aluminum body from the enclosed part of the headphones. He also wired up a tactile switch to act as the power button for the Bluetooth module.

Details are scarce on how the speakers are wired between the module and the jack. But we think he simply wired them in parallel rather than using a switched jack. You can see a quick demo after the break but it really doesn’t augment the build details at all.

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Custom Wireless Headphone Charging Station

We’ve come to expect quite a lot of convenience from our technology, to the point where repeatedly plugging in a device for recharging can seem tedious. Hackaday regular [Valentin Ameres] decided to ditch the plugs and built his own wireless headphone charger. We’ve seen [Valentin's] work before, and one thing’s for certain: this guy loves his laser cutter. And he should, considering it’s churned out key components for a gorgeous Arc Reactor replica and his Airsoft Turret. [Valentin] fired it up yet again to carve the charging stand out of acrylic, then used a small torch and the edge of a table to bend the stand into shape.

He sourced the needed coils online and soldered the receiving coil to a spare miniUSB plug. These components are glued onto a laser-cut acrylic attachment, which fits against the side of the headphone and is held in place by plugging directly into the earpiece’s miniUSB jack. The headphones rest on the laser-cut charging stand, which has an extrusion of acrylic on one side that holds the emitter coil in position against the receiver coil. [Valentin] also added a simple momentary switch at the top of the stand to activate both the emitter coil and a status LED when pressed by the headphones.

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Bluetooth Audio Adapter Hacked to Switch Off Amplified Speakers

This Bluetooth Audio Adapter is meant to connect a Bluetooth audio source (like a smartphone or tablet) to a speaker system with a plain old line-in connection. It has the ability to automatically connection when the Bluetooth device comes into range. Sounds convenient until [Andreas Pösch] points out that he still has to switch the speakers on and off manually. This hack automates the entire thing using a bit of additional hardware.

If you look closely you’ll see that the black cables have barrel jacks. This is a power pass-through rig that he whipped up. The protoboard includes a 7805 linear regulator which feeds power to the green circuit board in lieu of it’s original power adapter. A MOSFET switches outbound power headed for the speakers. All of it fits inside of the original enclosure, and he only had to add one port for the AC adapter.

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