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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Rubidium Disciplined Real Time Clock

[Cameron Meredith] starts the Hackaday.io page for one of his projects by quoting a Hackaday write-up: “A timepiece is rather a rite of passage in the world of hardware hacking“. We stand by that assertion, but we’d say most of the clocks we feature aren’t as capable as his project. He’s made a real-time-clock module controlled by a rubidium frequency standard, and since it also includes a GPS clock he can track local time dilation effects by comparing the two.

Surplus rubidium standards are readily available, but each description of one seems to feature a lot of old-fashioned hardware hacking simply to get it working. This one is no exception, an unusual connector had to be replaced and an extra power supply module attached. Once those modifications had been made and a suitable heatsink had been attached, he was able to bring the rubidium standard, an RTC module, and GPS module together with an ATMega32U4 miniature Arduino-compatible board and an LCD display. The firmware is functional, but he admits it is not finished.

All the project’s files can be found on the Hackaday.io page linked above. Future plans include also monitoring the NIST WWVB radio time signal from Fort Collins, Colorado, for an extra time dilation comparison.

We’ve featured innumerable clocks over the years here at Hackaday, but among them have been a few based upon atomic standards. More than one has been used as a lab reference standard, but most similar to this build is [Max Carters] experiments to check the accuracy of an atomic standard, also using the WWVB transmissions.

Catching Lightning With High Voltages And A Kite

Flying a kite on a stormy day is not the wisest thing to do, except, of course, you’re intentionally trying to catch a lightning bolt. The guys from [kreosan] replicated the famous experiment, with which Benjamin Franklin once set out to prove the electrical nature of lightning.

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Solenoid Engine with Woodworking Chops

Simple, elegant, and well executed. This solenoid engine build is everything we’ve come to love about [Matthias Wandel]’s work. If you don’t recognize his name you probably remember the name of his site: Wood Gears.

In what feels like an afternoon project he put together a solenoid engine. It translates the linear motion of a small solenoid into the circular motion of a flywheel. The only specialized part in this hack is the solenoid. It has a pretty long throw and includes a hinge pin at the end.

The rest is crafted mostly of wood — it is admirable how he uses that table saw like a surgeon uses a scalpel. The wooden components include a base, flywheel, very interesting bearing blocks, and a few mounting brackets to hold everything in just the right place. Add to this a coat hanger for the cam shaft, the internals of a terminal strip for the cam, some heavy gauge wire, and you’re in business. The latter two make up a clever electrical switch that synchronizes the drive of the solenoid with the flywheel.

It’s amusing to hear [Matthias] mention that this engine isn’t very practical. We still think the project has merit — it’s great for learning about how simple an engine can be, and for developing an intuitive appreciation for how great commercially available motors and engines actually are. Plus, if you can mimic these fabrication techniques you can build anything. Great work on this one [Matthias], another thing of beauty!

Check out his video below, then go back and check out his air-powered engine and of course, a hack that actually uses wood gears.

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Hackaday Prize Entry: Theia IoT light-switch

There are it seems no wireless-enabled light switches available in the standard form factor of a UK light switch. At least, that was the experience of [loldavid6], when he decided he needed one. Also, none of the switches he could find were open-source, or easy to integrate with. So he set out to design his own, and the Theia IoT light switch is the result.

In adapting a standard light switch, he was anxious that his device would not depend on the position of the switch for its operation. Therefore he had to ensure that the switch became merely an input to whichever board he designed, rather than controlling the mains power. He settled upon the ESP8266 wireless-enabled microcontroller as the brains of the unit, with a relay doing the mains switching. He first considered using an LNK304 off-line switching PSU chip to derive his low voltages, but later moved to an off-the-shelf switch-mode board.

So far two prototype designs have been completed, one for each power supply option. Boards have been ordered, and he’s now in the interminable waiting period for international postage. All the KiCad and other files are available for download o the project’s hackaday.io page, so you can have a look for yourselves if you are so inclined.

You might ask why another IoT light switch might be needed. But even though they are now available and inexpensive, there is still a gap for a board that is open, and more importantly does not rely on someone else’s cloud backend. Plus, of course, this board can be used for more than lighting.

Light bulb image: Осадчая Екатерина (Own work) [CC BY-SA 4.0], via Wikimedia Commons.

Cute but Serious-Faced Automata Produce a Pour Over

robot-cafe-cartCheck out the great workmanship that went into [TonyRobot]’s coffee vending version of ROBOT CAFE at Tokyo Maker Faire 2016. We’d really like to see this in action, so if anyone has more success than we did at tracking down more info (especially if it’s video) let us know in the comments below. We spot laser-cut wood making up the clever scoop design (and the numerous gears within it) but simply must know more.

Technically this is less “robot” and more “automata“. The cart charmingly fuses vending machine practicality with a visual display… and a great one at that. The aesthetic of the Robot Cafe leaps over the uncanny valley and fully embraces lovable robot faces.

Coffee is ground by a manual-style grinder into a scoop, which is then dumped into a pour-over filter. The hot water is then raised from below to pour over the grounds. These characters can be reconfigured based on the needs of the venue. The creator page linked above has three pictures of the same cart and same robo-baristas, but they are fishing for sodas instead. The glass bottles are lifted through the hole you can see on the right of the cart’s counter, using a fishing line with a magnet to grip the metal bottle cap.

We were delighted when robot vending machines started to appear — the kind with a big glass window and a gantry that grabs your corn-syrupy beverage. But take inspiration from this. True vending nirvana is as much theater as it is utility.

[via Gizmodo Japan]

Pressure Plate LED Coasters!

Looking to use up some more of his flexible LED strip, Hackaday alum and Tindie writer [Jeremy Cook] tried for a funky accent to his dinner or coffee table: light up coasters.

Using his CNC router to carve out two pieces of translucent plastic to house four 3V CR2032 batteries, four pieces of LED strip, and some wire, [Cook] had created a pressure plate circuit that activated once a drink is set on it. The original layout of the circuit, however, didn’t work, and the space for the LED strips proved to be too small. A quick redesign and some more time with his router resulted in an almost working product. Initially intending to use screws to secure the coaster, hot glue provided the perfect amount of spring once he had thinned out the coaster top to allow it to more easily flex and complete the circuit.

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