Extensive Modification Of DSLR Includes High Quality Audio

Modern DSLR cameras are incredible pieces of technology that can take excellent high-quality photos as well as record video and audio. However, as they become jacks of all trades they risk being masters of none, and the audio quality in modern DSLRs certainly reflects that old cliche. To get true high-quality audio while recording with a camera like this Canon 80d, you’ll either need a secondary audio recording device or you’ll need to interface one directly into the camera itself.

This build from [Tony] aka [Carnivore] goes into the inner workings of the camera to add an audio mixer to the camera’s audio input, allowing for multiple audio streams to be recorded at once. First, he removed the plastic around the microphone port and attached a wire to it that extends out of the camera to a 1/8″ plug. While he had the case open he also wired a second shutter, added a record button to a custom location on the front of the camera, and bypassed a switch which prevents the camera from operating if the battery door isn’t closed.

With those modifications in place, he removed the internal flash from the camera before closing the body. A custom 3D printed mount was placed in the vacant space which now houses the audio mixer, a SR-AX100 from Saramonic. This plugs in to the new microphone wire from earlier in the build, allowing the camera to have an expanded capacity for recording audio.

While [Tony] has a fairly unique use case for all of these modifications to an already $1000 camera, getting into the inner workings of DSLRs isn’t something to shy away from if you need something similar done. We’ve even seen modifications to cameras like these to allow for watercooling during video recording.

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Listening To Long Forgotten Voices: An Optical Audio Decoder For 16 Mm Film

Like many of us, [Emily] found herself on COVID-19 lockdown over the summer. To make the most of her time in isolation, she put together an optical audio decoder for old 16 mm film, built using modern components and a bit of 3D printing.

It all started with a broken 16 mm projector that [Emily] got from a friend. After repairing and testing the projector with a roll of film bought at a flea market, she discovered that the film contained an audio track that her projector couldn’t play. The audio track is encoded as a translucent strip with varying width, and when a mask with a narrow slit is placed over the top it modulates the amount of light that can pass through to a light sensor connected to speakers via an amplifier.

[Emily] used a pair of razor blades mounted to a 3D printed bracket to create the mask, and a TI OPT101 light sensor together with a light source to decode the optical signal. She tried to use a photoresistor and a discrete photodiode, but neither had the required sensitivity. She built a frame with adjustable positions for an idler pulley and the optical reader unit, an electronics box on one end for the electronic components, and another pulley attached to a stepper motor to cycle a short loop of the film.

Most of the projects we see involving film these days are for creating digital copies. You can digitize your old 35 mm photo film using a Raspberry Pi, some Lego pieces, and a DSLR camera, or do the same for 8 mm film with a 3D printed rig. Continue reading “Listening To Long Forgotten Voices: An Optical Audio Decoder For 16 Mm Film”

Squeezing Every Bit From An ATMega

While the ATMega328 is “mega” for a microcontroller, it’s still a fairly limited platform. It has plenty of I/O and working memory for most tasks, but this Battleship game that [thorlancaster328] has put together really stretches the capabilities of this tiny chip. Normally a Battleship game wouldn’t be that complicated, but this one has audio, an LED display, and can also play a fine rendition of Nyan Cat to boot, which really puts the Atmel chip through its paces.

The audio is played through a 512-byte buffer and an interrupt triggers the microcontroller when to fill the buffer while it works on the other processes. The 12×12 LED display is also fed through a shift register triggered by the same interrupt as the audio, and since the build uses so many shift registers the microcontroller can actually output four separate displays (two players, each with a dispaly for shots and one for ships). It will also eventually support a player-vs-computer mode for the battleship game, and also has a mode where it plays Nyan cat just to demonstrate its own capabilities.

We’re pretty impressed with the amount of work this small microcontroller is doing, largely thanks to code optimization from its creator [thorlancaster328]. If there’s enough interest he also says he will provide the source code too. Until then, be sure to check out this other way of pushing a small microcontroller to its limits.

Thanks to [Thinkerer] for the tip!

Building Distributed Mode Loudspeakers With Plywood

Distributed-mode loudspeakers work rather differently from the typical drivers used in 99% of applications. Instead of using piston-like motion to create sound waves, they instead rely on exciting an entire panel to vibrate and thus produce sound. [JGJMatt] decided to build a pair of bookshelf-sized units, with great results.

The build begins with a pair of 44mm DML exciters, readily available online. These had to be modified to remove their stock metal mounting plates that degraded the sound output in early tests. Instead, 3D printed pieces were used to mount the exciters to the 3mm plywood boards, which were lasercut to act as the main DML panels. Additionally, whizzer cones were fitted to the panels in an effort to further boost the high frequency response of the speakers. The speaker stands are assembled out of more 3D printed pieces and aluminium rods, giving a clean, modern look to the final product.

The performance of the speakers is admirable based on the test video, though [JGJMatt] notes that they should be paired with a subwoofer in use as the DML units do not readily produce frequencies below 100Hz. We’ve seen similar builds before on a larger scale, too. Video after the break.

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Booting A PC From Vinyl For A Warmer, Richer OS

If you’ve scrolled through the list of boot options offered on any PC’s BIOS, it reads like a history of storage technology. Up top we have the options to boot from disk, often a solid-state drive, then USB disk, optical drive, removable media, and down the bottom there’s usually an option to boot from the network. Practically no BIOS, however, has an option to boot a PC from a vinyl record — at least until now.

Clearly a project from the “Because why not?” school of hacking, [Jozef Bogin] came up with the twist to the normal booting process for an IBM-PC. As in the IBM-PC — a model 5150, with the putty-colored case, dual 5-1/4″ floppies, and one of those amazing monochrome displays with the green slow-decay phosphors. To pull off the trick, [Jozef] leverages the rarely used and little known cassette tape interface that PCs had back in the early days. This required building a new bootloader and burning it to ROM to make the PC listen to audio signals with its 8255 programmable peripheral interface chip.

Once the PC had the right bootloader, a 64k FreeDOS bootable disk image was recorded on vinyl. [Jozef] provides infuriatingly little detail about the process other than to mention that the audio was sent directly to the vinyl lathe; we’d have loved to learn more about that. Nonetheless, the resulting 10″ record, played back at 45 RPM with some equalization tweaks to adapt for the RIAA equalization curve of the preamp, boots the PC into FreeDOS just fine, probably in no more time than it would have taken to boot from floppy.

It’s may not be the first time we’ve seen software on vinyl, but it’s still a pretty cool hack. Want to try it yourself but lack a record-cutting lathe? Maybe laser-cutting your boot disc will work.

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Axe Hacks: New Sounds For Your Electric Guitar Beginning From What Makes Them Tick

Creating music is a perfect hobby for anyone into hacking, and the amount of musical hacks and self-made instruments we come across here makes that supremely evident. It’s just a great match: you can either go full-on into engineering mode as music is in the end “just” applied physics, or simply ignore all of the theory and take an artistic approach by simply doing whatever feels right. The sweet spot is of course somewhere in between — a solid grasp of some music theory fundamentals won’t hurt, but too much overthinking eventually will.

The obvious choice to combine a favorite pastime like electronics or programming with creating music would be in the realm of electronic music, and as compelling as building synthesizers sounds, I’ll be going for the next best thing instead: the electric guitar. Despite its general popularity, the enormous potential that lies within the electric guitar is rarely fully utilized. Everyone seems to just focus on amp settings and effect pedals when looking for that special or unique sound, while the guitar itself is seen as this immutable object bestowed on us by the universe with all its predestined, magical characteristics. Toggle a pickup switch, and if we’re feeling extra perky, give that tone pot a little spin, that’s all there is to it.

The thing is, the guitar’s electrical setup — or wiring — in its stock form simply is as boring and generic as it can get. Sure, it’s a safe choice that does the job well enough, but there’s this entirely different world of tonal variety and individual controllability locked inside of it, and all it really takes is a screwdriver and soldering iron to release it. Plus, this might serve as an interesting application area to dive into simple analog electronics, so even if guitars aren’t your thing yet, maybe this will tickle your creativity bone. And if bass is more your thing, well, let me be ignorant and declare that a bass is just a longer guitar with thicker, lower-tuned strings, meaning everything that follows pretty much applies to bass as well, even if I talk about guitars.

However, in order to modify something, it helps to understand how it functions. So today, we’ll only focus on the basics of an electric guitar, i.e. what’s inside them and what defines and affects their tone. But don’t worry, once we have the fundamentals covered, we’ll be all settled to get to the juicy bits next time.

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That Elusive Valve Amp Sound, For Not A Lot! (There Has To Be A Catch)

It was with considerable interest last month that I set out to track down where in the world there are still factories making tubes. My research found them in Slovakia, Russia, and China, and it’s fairly certain I didn’t find all the manufacturers by any means. There appeared to be a whole class of mundane tubes still in production that weren’t to be found on their glossy websites. A glance at any outlet through which Chinese modules can be bought will find this type of tube in small audio amplifier projects, and some of them can be astoundingly cheap. When faced with cheap electronics of course I’m tempted to buy some, so I parted with about £10 ($12.50) and bought myself a kit for a two-tube device described as a stereo preamplifier and headphone amplifier.

An Unusual Tube Choice For Audio

What I received for my tenner was a press-seal bag with a PCB and a pile of components, and not much else. No instructions, which would have been worrisome were the board not clearly marked with the value of each component. The circuit was on the vendor’s website and is so commonly used for these sort of kits that it can be found all over the web — a very conventional twin common-cathode amplifier using a pair of 6J1 miniature pentodes, and powered through a +25 V and -25 V supply derived from a 12 VAC input via a voltage multiplier and regulator circuit. It has a volume potentiometer, two sets of phono sockets for input and output, and the slightly naff addition of a blue LED beneath each tube socket to impart a blue glow. I think I’ll pass on that component.

The 6J1 seems to be ubiquitous throughout the Chinese kits, which is surprising when you understand that it’s not an audio tube at all. Instead it’s a small-signal VHF amplifier, a rough equivalent of the European EF95, and would be much more at home in an FM radio receiver or turret TV tuner from the 1950s. I can only assume that somewhere in China there’s a tube factory tooled up for radio tube production that is targeting this market, because another tube you will see in audio power amplifier kits is the FU32 or QQV03-20 in European parlance, a large power beam tetrode that might have been found in a 1950s military radio transmitter. Still just as if you were to use an RF transistor in an audio circuit it would give good account of itself, so it is with an RF tube. There is no reason a 6J1 won’t do an acceptable job in a circuit such as this one.

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