Let’s say you use an SD card-base portable audio recorder for work – doing an interview, perhaps. Things go well until one day, you turn the recorder off before stopping the recording. Without pressing that big red Stop button, the file doesn’t close, and you’re left with a very large 0kB file on the SD card. How do you get it back? There are tools that will do it for you, but they cost money. You can do it yourself with a hex editor, though, and it’s actually pretty easy.
The software required for this feat of data recovery is Roadkil’s Disk Imager to dump all the bits on the SD card to an image file, the free version of ISO Buster to show the block addresses and length of each file, and the hex editor of your choice. The process starts as simply an experiment for hot to create an MP3 file by cutting and pasting bits into a hex editor. A good file was found in the hex editor, copied to a new file, and played. Everything works so far; great.
For the actual data recovery, a spreadsheet was created to make an educated guess as to where the lost file should be. Starting at this address, about 90MB of data was copied into a new hex editor window. This is where the recovery hit a snag. Because the SD card was plugged into a Mac before, a bunch of data was written on the card. This went into the first available place on the disk, which just happened to be the header of the lost MP3 file.
That’s not a problem; there’s already the header from an MP3 file sitting in a hex editor from the first experiment to see if this was possible. By copying a few hundred bytes to the front of the lost file, the file was corrected just enough that an MP3 player could reconstruct the file.
It’s not perfect – the first fifty seconds of the interview was garbled. The rest of the interview was saved, though, and that’s much better than losing the entire thing. Thanks [Lewin] for sending this one in.
Continue reading “Manual Data Recovery With A Hex Editor”
[Pat]’s friend got a Pono for Christmas, a digital audio player that prides itself on having the highest fidelity of any music player. It’s a digital audio device designed in hand with [Neil Young], a device that had a six million dollar Kickstarter, and is probably the highest-spec audio device that will be released for the foreseeable future.
The Pono is an interesting device. Where CDs have 16-bit, 44.1 kHz audio, the Pono can play modern lossless formats – up to 24-bit, 192 kHz audio. There will undoubtedly be audiophiles arguing over the merits of higher sampling rates and more bits, but there is one way to make all those arguments moot: building an MP3 player out of an oscilloscope.
Digital audio players are limited by the consumer market; there’s no economical way to put gigasamples per second into a device that will ultimately sell for a few thousand dollars. Oscilloscopes are not built for the consumer market, though, and the ADCs and DACs in a medium-range scope will always be above what a simple audio player can manage.
[Pat] figured the Tektronicx MDO3000 series scope sitting on his bench would be a great way to capture and play music and extremely high bit rates. He recorded a song to memory at a ‘lazy’ 1 Megasample per second through analog channel one. From there, a press of the button made this sample ready for playback (into a cheap, battery-powered speaker, of course).
Of course this entire experiment means nothing. the FLAC format can only handle a sampling rate of up to 655 kilosamples per second. While digital audio formats could theoretically record up to 2.5 Gigasamples per second, the question of ‘why’ would inevitably enter into the minds of audio engineers and anyone with an ounce of sense. Short of recording music from the master tapes or another analog source directly into an oscilloscope, there’s no way to obtain music at this high of a bit rate. It’s just a dumb demonstration, but it is the most expensive MP3 player you can buy.
When you get that itch to build something, it’s difficult to stop unless you achieve a feeling of accomplishment. And that’s how it was with [Rohit’s] boombox build.
He started out with a failing stereo. He figured he could build a replacement himself that played digital media but his attempts at mating microcontrollers and SD cards was thwarted. His backup plan was to hit DX for a cheap player and he was not disappointed. The faceplate he found has slots for USB and SD card, 7-segment displays for feedback, and both buttons and a remote for control. But this little player is meant to feed an amplifier. Why buy one when you can build one?
[Rohit] chose ST Micro’s little AMP called the TDA2030 in a Pentawatt package (this name for a zig-zag in-line package is new to us). We couldn’t find stocked chips from the usual suspects but there are distributors with singles in the $3.50-5 range. [Rohit] tried running it without a heat sink and it gets hot fast! If anyone has opinions on this choice of chip (or alternatives) we’d love to hear them.
But we digress. With an amp taken care of he moved onto sourcing speakers. A bit of repair work on an upright set got them working again. The bulky speaker box has more than enough room for the amp and front-end, both of which are pretty tiny. The result is a standalone music player that he can be proud of having hacked it together himself.
Headphones have become ubiquitous these days. Thanks to the iPod and the smartphone, it’s become commonplace to see someone wearing a pair of earbud style headphones. Earbuds aren’t always comfortable though. On some people they are too loose. On others, the fit is so tight that they cause pain.To that end, we’ve found a few great solutions for this problem.
[cptnpiccard] has documented his custom molded Sugru earbuds in an Imgur gallery. He’s molded a pair of standard earbuds into a cast of his ear. He uses them both for hearing protection and tunes while skydiving. Sugru’s FAQ states that while the cured material is safe for skin contact (and in ear use) some people are sensitive to the uncured material.
While discussing his project on Reddit, a few users chimed in and mentioned they’ve made custom molded earbuds using Radians custom earplug kits. The Radians material hardens up in only 10 minutes, which beats waiting an hour for Sugru.
The absolute top of the food chain has to be building your own triple driver in ear monitors, which is exactly what [marozie] has done. Professional custom molded monitors can cost over $1000, which puts them in the realm of professional musicians and audiophiles. [marozie] discovered that mouser stocks quite a few transducers from Knowles. These tiny speakers don’t come cheap, though; you can spend upwards of $70 just for a single driver.
[marozie] took a cast of his ear using an earmold impression kit. He used this cast to create a mold. From there it was a matter of pouring resin over his carefully constructed driver circuits and audio tubes. The resulting monitors look and sound incredible.
It goes without saying that making custom in ear monitors involves putting chemicals into you ears. The custom earmold kits come with tiny dams to keep the mold material from going in too far and causing damage. This is one of those few places where we recommend following the instructions. Click past the break to see a demo video of the ear molding process.
Continue reading “DIY Custom Molded Earbud Roundup”
[Matt]’s been working on a small hombrew MP3 player, and although it’s not much more useful than an iPod Shuffle, sometimes that’s all you need. Besides, it turned out to be a beautiful project, completely custom, and a great example of what a high resolution 3D printer can do with an enclosure design.
Inside Bumpy is an ATMega32u4 with a VS1003 MP3 codec IC. The device is powered by a 1000mAh lithium battery, and the user interface is an exercise in simplicity; a single click/scroll wheel changes the volume, toggles play and pause, and selects the next or previous track. Eight LEDs mounted in the center of the board glow through the case for status, volume, and interface feedback.
By far the most impressive part of Bumpy is the case. It was printed at [Matt]’s place of employment – Formlabs – in white UV curing resin. The pictures show a surface finish that would be difficult to replicated on a squirting plastic style 3D printer, with a textured, bumpy surface that inspired the name.
This AM radio looks a bit like it did coming out of the factory. But there are a lot of changes under the hood and that faceplate is a completely new addition. The project really is a restoration with some augmentation and [Michael Ross] did a great job of documenting the project.
The Kenyon radio was built in 1946 and uses vacuum tubes for the amplifier. Considering its age this was in relatively good shape and the first thing that [Michael] set out to do was to get the electronics working again. It involved replacing the messy collection of capacitors inside. He then cleaned up the tubes, checking for any problems, and put the electronics back together to find they work great!
He cleaned up the chassis and gave it a new coat of finish. The original dial plate was missing so he built a wood frame to match a dial scale he ordered. The bell-shaped brass cover hides the light that illuminates the dial.
He could have stopped there but how much do people really listen to AM radio these days? To make sure he would actually use the thing he added an Arduino with an MP3 shield. It patches into the antenna port via a relay, injecting modern tunes into the old amplifier circuit. Catch a glimpse of the final project in the video after the break.
Continue reading “AM tube radio restored and given MP3 playback too”
[Ivan] made something special with this car stereo hack. He altered the head unit to play MP3 files from USB and added an auxiliary line-in. But looking at it you’d never know. That’s thanks to the work he did to create a false button hiding the audio jack, and a false cassette hiding the USB port and MP3 player display. Possibly the best part is that the radio itself still works like it always did.
There are several components that went into making the system work. It starts with the cassette/radio head unit. To that he added an MP3 player with remote which he picked up on Deal Extreme. He wasn’t a huge fan of the IR remote that came with it so he rolled in a remote that mounts on the steering wheel. To pull everything together he used a PIC 16F877a. The microcontroller controls the lines which tell the head unit if a tape has been inserted. When [Ivan] selects either the Aux input or wants to play MP3s from a thumb drive the uC forces the head unit into cassette mode and the audio from the player is injected into the cassette player connections.
To help deter theft [Ivan] created two false fronts. The end of a cassette tape plugs into the USB port. The rewind button plugs into the Aux jack. You can get a good look at both in the demo after the break.
Continue reading “MP3/USB/Aux hack hidden behind cassette facade”