Sending Music Long Distance Using A Laser

This isn’t the first time we’ve seen DIYers sending music over a laser beam but the brothers [Armand] and [Victor] are certainly in contention for sending the music the longest distance, 452 meter/1480 feet from their building, over the tops of a few houses, through a treetop and into a friend’s apartment. The received sound quality is pretty amazing too.

In case you’ve never encountered this before, the light of the laser is modulated with a signal directly from the audio source, making it an analog transmission. The laser is a 250mW diode laser bought from eBay. It’s powered through a 5 volt 7805 voltage regulator fed by a 12V battery. The signal from the sound source enters the circuit through a step-up transformer, isolating it so that no DC from the source enters. The laser’s side of the transformer feeds the base of a transistor. They included a switch so that the current from the regulator can either go through the collector and emitter of the transistor that’s controlled by the sound source, giving a strong modulation, or the current can go directly to the laser while modulation is provided through just the transistor’s base and emitter. The schematic for the circuit is given at the end of their video, which you can see after the break.

They receive the beam in their friend’s apartment using solar cells, which then feed a fairly big amplifier and speakers. From the video you can hear the surprisingly high quality sounds that results. So check it out. It also includes a little Benny Hill humor.

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Hacker Places To Visit: Musée des Arts et Métiers in Paris

I think the restaurant is really close now...
I think the restaurant is really close now… CC: E. Broeks

The best way to pull off this deception: tell your significant other that you’d want nothing more than a romantic week in Paris. Arrive in Paris, stash your bags, and then take either the number three or eleven Metro. When you get to the station that looks like the inside of a giant steam engine, Arts et Métiers, get out. You’re now ten Euros away from one of the coolest museums a hacker could visit.

A significant portion of modern science’s beginnings is sitting in the Musée, polished and beautiful. Most of them are housed in cabinets so old they’re part of the exhibit. Now, the Henry Ford museum in Detroit Michigan is a monument to industrialization, and cool in its own right, but it leaves some questions unanswered. We’re all spoiled by desktop CNCs, precision measurement tools for pennies, and more. How did we get here? How did they measure a shaft or turn a screw before precision digital micrometers? What did early automation look like? Early construction?

Also did I mention it has Foucault’s Pendulum? You know, the one that finally convinced everyone that the Earth rotated around an axis? No big deal.

The museum has a few permanent exhibits: instruments scientifique, matériaux, construction, communication, énergie, mécanique et transports.

What kind of basic museum would have just one example of Pascal's work?
What kind of basic museum would have just one example of Pascal’s work? CC: Anton Lefterov

Instruments Scientifiques was one of my favorites. Not only did it include old scientific instruments, it had sections containing some of the original experiments in optics, computation, and more. For example you can see not just one but a few original examples of Pascal’s Pascaline, arguably the first mechanical calculators in the modern era to be used by the layman for every day calculation, signed by Pascal. It’s also worth noting just how incredible the workmanship of these tools are. They’re beautiful.

Matériaux was initially a disappointment as I entered it from the wrong end. For me it started of with a tragically boring and simplistic display on recycling materials designed primarily to torture children on field trips. Luckily it quickly ramped into a fascinating display on materials manufacturing technology. How did we go from hand looms to fully automated Jacquard looms (of which you can see some of the first examples) to our modern day robotic looms? How did ceramic evolve? What was early steelmaking like? It’s very cool and models are all in beautiful condition.

It reeked of copper, machine oil, and phenolics. They just don't make computers like they used to.
It reeked of copper, machine oil, and phenolics. They just don’t make computers like they used to.

By the time I got to Communication I was reaching the limit of my endurance and also what you can fit into a single day of the museum. It’s a large building. It was packed through many of the early examples of computing, television, and space. There was quite a display of early camera equipment. You could get close enough to some truly massive old computers to smell the still off-gassing phenolics.

Construction held my interest for a long time. It’s not my usual interest, but after living in Paris for a month or so I was absolutely burning with curiosity. How did anyone without a single powered crane or vehicle build so many buildings out of stone? It’s packed for four rooms and two stores from floor to ceiling of beautiful little wood models explaining exactly how.

Énergie was quite cool. It followed the development of steam power for the most part. It started with primitive waterwheels. Moved on to turbines. Then showed the gradual increase in complexity until the the modern day. It had some internal combustion too, but much of that was reserved for the transports section of the museum. It also had some interactive displays to entertain children and Hackaday writers. However they were in desperate need of an oiling and this is by far the most ear-piercingly squeaky exhibit in the whole building.

A lathe fit for a king!
A lathe fit for a king! CC: Rama

Mécanique is competing with instruments scientifique as my favorite exhibit. Have you ever wanted to see hundreds of examples of screw machines, old lathes, and the evolution of the milling machine? What about models of the factories that built steam engines or massive wagon wheels. They even had a lathe that belonged to a French king. Apparently he thought metalworking was the way to get in touch with the common people.

Transports was a nice exhibit, but it fell a little short for me since I’d been to the aforementioned Henry Ford museum. However, it covered the history of some of the European automobile manufacturers pretty well. Had a nice section on trains and subways. And even had some models of the ships used in the European Space Agency.

The entrance of the school. Has some original, “flying,” machines. CC: King Boshi

The last exhibit is the museum itself. It’s an historic building. It was originally built as a school for training engineers in 1794 but as the school grew out of it, it slowly transformed into the museum it is today. The architecture is beautiful. It’s adorned in stone and statue like all the French museums. It also has sections cut out in some of the higher storeys of the building so you can see how it was constructed.

Part of its beauty is also related to the school swallowing up the Priory of Saint Martin des Champs (Google translate does a great job if you don’t read French). The Priory is a beautiful old church, founded in 1079. It was home to the last trial by combat the country would see. You can piece together the story between the two pages dedicated to the combatants Jean de Carrouges and Jacques Le Gris.

The muses of agriculture and industry now look over the sanctuary.
The muses of agriculture and industry now look over the sanctuary.

The final display in the museum is in the church. It holds Foucault’s pendulum, dangling from the center of the sanctuary. If you get there early enough in the day you may get to watch it knock over a peg or two and prove the rotation for yourself.

Rather than the statues of the saints there are statues of the muses of Industrie and Agriculture. The hall is filled with more exhibits. There are cutaway original automobiles. A model of the Statue of Liberty. A catwalk lets you take a high view of the surroundings. It is also beautiful in and of itself. The church is well maintained and painted in the style original to them.

If you find yourself in Paris with a few hours (or days) to spare I highly recommend this museum. Any technical person would be hard pressed to leave uninspired and unawed by the display. It’s good to get a perspective on the past.

Featured Photo CC: Roi Boshi


Retrotechtacular: Fantastic Backyard Inventions of Yore

News corporation [British Pathé] created many newsreels and documentaries throughout their 60-year history. Recently, the company released scores of films from their archives and put them on the internet. Here is a delightful collection of short films they created that highlight strange and wonderful inventions in various fields, including transportation and communication.

One of the standout inventions is the Dynasphere, a mono-wheeled vehicle that probably deserves its own week in the Retrotechtacular spotlight. There are a couple of pedal-powered planes that may have inspired the Gossamer Condor, and a hover scooter that resembles an air hockey striker and doubles as a leaf blower. In another film, a man drives a Vespa to the banks of the Thames and parks it. He pulls a fin down from each side of the scooter, turning it into a seafaring craft. When he snaps his fingers, a cute girl appears from somewhere just outside the frame. She climbs on the back, and they take off across the water.

The average running time of these films is about two minutes. Some of them are much shorter, prompting many questions. Fortunately, most of the video descriptions have links with more information about these marvelous inventions. Almost all of the inventors in these films show a complete disregard for safety, but nearly everyone involved seems to be having the time of their lives.

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Solar-Cell Laser Communication System

Forget the soup cans connected by a piece of string. There’s now a way to communicate wirelessly that doesn’t rely on a physical connection… or radio. It’s a communications platform that uses lasers to send data, and it’s done in a way that virtually anyone could build.

This method for sending information isn’t exactly new, but this project is one of the best we’ve seen that makes it doable for the average tinkerer. A standard microphone and audio amplifier are used to send the signals to the transmitter, which is just a typical garden-variety laser that anyone could find for a few dollars. A few LEDs prevent the laser from receiving too much power, and a solar cell at the receiving end decodes the message and outputs it through another amplifier and a speaker.

Of course you will need line-of-sight to get this communications system up and running, but as long as you have that taken care of the sky’s the limit. You can find incredibly powerful lasers lying around if you want to try to increase the communication distance, and there are surprisingly few restrictions on purchasing others that are 1W or higher. You could easily increase the range, but be careful not to set your receiving station (or any animals, plants, buildings, etc) on fire!

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Wouldn’t Tweeting in Morse Code be More Like “Pecking”?

If you find yourself glued to social media and also wish to know Morse code… we can think of no better invention to help hone your skills than the Twitter Telegraph. This vintage to pop culture mashup by [Devon Elliott] is a recent project that uses a sounder from the 19th century to communicate incoming tweets with dots and dashes.

Back in the day when everyone was connected by wire, the sounder was a device on the receiving end of the telegraph which translated the incoming signal to an audible clicking. Two tall coils sat with a metal tab teetering between them. When electricity surged into one of the coils it would magnetize, pulling the tab downward in a pattern which mimicked the incoming current sent from the other end. [Devon] decided to liberate the sounder from its string-and-two-can origins and use a more modern source of input. By adding a FONA board which comes equipped with a SIM card, the device was capable of connecting and receiving data from the Internet. An Arduino is responsible for taking the data received and translating it into Morse code using the Mark Fickett’s Arduinomorse library, and then sending it out through an I/O pin to the sounder itself to be tapped.

The finished project is connected to a cellular network which it uses to receive SMS messages and tweets. By mentioning the handle @ldntelegraphco you can send the Twitter Telegraph your own message which will be tapped in code for everyone in the vicinity to hear… which is worth giving a try for those of you curious types. Lastly, if you have an interest in taking a look at the code for your own use, it is available on [Devon’s] github.

8 Bit Message in a Digital Bottle

As seasoned data-travelers, we’re used to wielding the internet to send messages and communicate to others without any limitations. No one has to be stranded on a figurative island blowing smoke signals… unless of course they wanted to be. What [Harm Alexander Aldick] has done with his project “Lorem Ipsum”, is create a situation where others can only communicate to him through a sort of message in a bottle. The bottle in this case is an electronic widget.

In this social experiment, [Harm] has stationed a small Ikea picture frame at his desk, which shows images and text sent to him in real-time from others in the world. With an Arduino as the brain, a small 8×8 LED matrix mounted at the bottom right of the frame displays the data received by means of an ethernet module. Anyone can use his web interface to modify the pixels of the matrix on a virtual version of the installation. Once sent, the message is transmitted through an IPv6 internet connection and is translated to UDP which the unit is controlled by.

[Harm]’s project investigates how people react when given the chance to send a message in complete anonymity to someone they don’t know… in of all things, the form of something as limited as 64 pixels. The project name “Lorem Ipsum” refers to the filler text used in graphic design to hold the place of what would otherwise be more meaningful information, so that it doesn’t detract from the experience of viewing the layout. Curious about what sort of ‘graphical experience’ I would come up with myself, I took a shot at punching away at [Harm’s] GUI. I got momentarily lost in turning the little red dots on and off and eventually turned out this little ditty:


It was supposed to be something of a triangle, yet turned into a crop circle… or pronged nipple. After it was sent, I wondered whether or not [Harm] actually saw it. In the case that he did, I can only imagine what I communicated to our fellow hacker abroad with my squall of dots. All of these thoughts though are the whole point of the project. Awesome work!

Sound card microcontroller/PC communication

The usual way send data from a microcontroller is either over RS-232 with MAX232 serial ICs, crystals, and a relatively ancient computer, or by bit-banging the USB protocol and worrying about driver issues. Not content with these solutions, [Scott] came up with sound card μC/PC communication that doesn’t require any extra components.

[Scott] bought a cheap USB sound card dongle on eBay (although a built-in sound card will do) and wired up the tip and ring of the plug to the microcontroller. The data is sent from the microcontroller a lot like Morse code – a short gap between pulses is a zero, a long gap is a one. This is parsed by a Python script using PyAudio. Synchronization, timing, and calibration is automatic because of a 10-bit ‘packet header’ explained in this video.

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