Gigabit Ethernet Through the Air

There are a couple of really great things about transmitting data using light as the carrier. It can be focused so that it doesn’t spill all over the neighborhood like radio signals do — giving it both some security against eavesdropping and preventing one signal from stepping on another’s toes. And while you can modulate radio signals up nearly to the carrier frequency, the few gigahertz we normally use for radio just won’t cut it for really high bit rates. Light gets you terahertz.

The Koruza project is an open-source, “inexpensive” system that aims to transmit 1 Gb/sec over distances around 100 meters, using modulated infrared light. The intended use-case is urban building-to-building communication at speeds that would otherwise require laying fiber-optic cables. Indeed, the system piggy-backs on existing fiber-optic equipment to get the job done, but the hard part is aligning the units to get maximum signal from point A to point B.

koruza-spec-info

Koruza does this by including motorized lenses on the 3D-printed chassis. You make a rough alignment with a visible green laser, and then fine-tune the IR beams from a web console where you get immediate feedback on how the received signal strength is changing. Both Koruza boxes have a Raspberry Pi inside and use normal networking for calibration and signal-strength statistics. It’s a really neat system, and it’s fully DIY’able except for the commodity fiber-optic bits.

We’ve always had a soft-spot in our heart for transmitting data over light beams. The Ronja project has been doing so since 2001, and over longer distances, with completely DIY hardware, if at a slower bitrate. And now that Li-Fi seems to be getting traction, we might see an unfocused equivalent running inside our homes.

Thanks [Pavel] for the tip!

UV Laser Projector Shines With Glow-in-the-Dark Vinyl

Mirror galvanometers were originally developed in the 17th century to precisely measure very small changes in current. Unlike other instruments of the day, a mirror galvanometer could clearly show minute current variations by translating tiny movements of the mirror into large movements of the light reflected off of the mirror. Before clean electrical amplification became possible, this was the best means of measuring tiny differences in current. True mirror galvanometers are very sensitive instruments, but hobby servos can be used as a low-fidelity alternative, like with this project on Hackaday.io created by [robives].

Using a mirror galvanometer is by far the most common technique for laser projection shows – it’s really the only way to move the laser’s beam quickly enough to create the visual illusion of a solid line in real time. A mirror galvanometer works by using coils to attract magnets attached to the mirror, allowing the angle of the mirror to change when current is applied to the coils. This movement is extremely small, but is amplified by the distance to the projection surface, meaning the laser’s beam can move huge distances in an instance. If you’ve ever seen a laser show, it almost certainly used this technique. But driving galvos requires a beefy DAC, so we can’t blame [robives] for wanting to keep it digital.

[robives’s] project side-steps the need for galvanometers by using glow-in-the-dark vinyl and a UV laser. The result is a laser beam trail which lasts much longer, which means that solid lines are visible without the need for high-speed galvos. A build like this lets you experiment with laser projections without dealing with sensitive mirror galvos, and instead use components that you probably already have sitting on your workbench.

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Increasing The Brightness Of A Philips LivingColors Lamp

[Martin] recently purchased a Philips LivingColors lamp. It’s a commercial product that basically acts as mood lighting with the ability to change to many different colors. [Martin] was disappointed with the brightness of his off-the-shelf lamp. Rather than spend a few hundred dollars to purchase more lamps, he decided to modify the one he already had.

[Martin] started by removing the front cover of his lamp. He found that there were four bright LEDs inside. Two red, one green, and one blue. [Martin] soldered one wire to the driver of each LED. These wires then connected to four different N-channel MOSFET transistors on a piece of protoboard.

After hooking up his RIGOL oscilloscope, [Martin] was able to see that each LED was driven with a pulse width modulated signal. All he had to do was connect a simple non-addressable RGB LED strip and a power source to his new driver board. Now the lamp can control the LED strip along with the internal LEDs. This greatly extends the brightness of the lamp with minimal modifications to the commercial product. Be sure to check out the video below for a complete walk through. Continue reading “Increasing The Brightness Of A Philips LivingColors Lamp”

Adding A Backlight To A Cheap Multimeter

We don’t all need super high quality electronic testing gear. Sometimes second-hand or inexpensive equipment is accurate enough to get the job done. Though it can be a bit annoying to miss out on some of those “luxury” features. [Ekriirke] had this problem with his cheap multimeter. He wished the LCD screen had a backlight for easier visibility, so rather than upgrade to a more expensive unit he just added one himself.

After opening up the multimeter [Ekriirke] found that it ran on a single 12V battery. He realized that the simplest thing to do would be to wire up four white LEDs in series. The four LEDs were arranged within the case off to each side of the LCD, one in each corner. The leads were bent at 90 degree angles and soldered together “dead bug” style. Thin strips of copper foil tape were attached to the PCB in such a way that the anode and cathode from the LEDs would make contact when the case was closed back up.

The tape wraps around to the other side of the PCB where there was more room for the next piece of the circuit. A capacitor, resistor, and transistor are used in conjunction with a momentary switch. This circuit allows [Ekriirke] to turn on the light for about ten seconds by pressing the button one time. The circuit also runs through the meter’s dial switch, preventing the LEDs from being turned on while the meter itself is turned off.

[via Reddit]

Flat Pack Elastic Band Lamp is a Thing of Beauty

[Matt] was looking for a project for his senior industrial design studio at Wentworth Institute of Technology. He ended up designing a clever lamp that can be flat packed. [Matt] started by drawing out designs on paper. He really liked the idea of combining curves with straight lines, but he wanted to translate his two-dimensional drawings into a three-dimensional shape.

zOz0ys6 - ImgurHaving access to a laser cutter made the job much easier than it could have been and allowed [Matt] to go through many designs for the lamp frame. The two main pieces were cut from acrylic and include mounting pegs for the elastic bands. The two plastic pieces are designed to slot together, forming a sort of diamond shape.

The final version of the lamp required that the elastic bands had holes punched in them for mounting. The holes were placed over the small pegs to keep the bands in place. [Matt] used 3/4″ industrial elastic bands for this project. He then used a 120V 15W candelabra light bulb to illuminate the lamp. The final design is not only beautiful, but it can be flat packed and manufactured inexpensively.

If you want more inspiration for artistically designed lamps check out this one that uses the corrugation in cardboards as a shade pattern.

[via reddit]

Incredibly Simple Stage For Product Photos

If you’ve ever tried to take nice photos of small objects in your home, you might have found that it can be more difficult than it seems. One way to really boost the quality of your photos is to get proper lighting with a good background. The problem is setting up a stage for photos can be expensive and time-consuming. [Spafouxx] shows that you don’t need to sink a lot of money or energy into a setup to get some high quality photos.

His lighting setup is very simple. Two wooden frames are built from scraps of wood. The frames stand upright and have two LED strips mounted horizontally. The LEDs face inwards toward the object of the photos. The light is diffused using ordinary parchment paper that you might use when baking.

The frames are angled to face the backdrop. In this case, the backdrop is made of a piece of A4 printer paper propped up against a plastic drink bottle. The paper is curved in such a way to prevent shadows. For being so simple, the example photo shows how clean the images look in the end.

Motion Light In Dark Stairwell Brightens Trips To The Basement

WARNNG: Walking around in the dark could be dangerous to your health! You may bump into something or worse, take a tumble down the stairs. Safety conscious [Ganesh] has come up with a solution for us folks too lazy to manually turn on a light. It’s a simple light controlled by a motion sensor that anyone can put together.

The meat and potatoes of the build is an off-the-shelf motion sensor, the same kind that is used in a home security system. We humans emit infrared energy and that is just what this sensor ‘sees’. The motion sensor is powered by 12 VDC and has a pair of DC output leads that are used to control a relay. [Ganesh] used an standard hobby relay board with built in power spike protection diode and transistor to supply the current required to trip the relay. Closing the relay sends mains power to the AC light bulb. Both the triggering threshold and the ‘on’ time are controlled by potentiometers integrated with the motion sensor.

Check the video out after the break of the device working its magic and lighting the way to [Ganesh’s] basement dungeon…

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