CNC machines can be very noisy, and we’re not talking about the kind of noise problem that you can solve with earplugs. With all those stepper motors and drivers, potentially running at high-speed, electrical noise can often get to the point where it interferes with your control signals. This is especially true if your controller is separated from the machine by long cable runs.
But electrical noise won’t interfere with light beams! [Musti] and his fellow hackers at IRNAS decided to use commodity TOSLINK cables and transmitter / receiver gear to make a cheap and hackable fiber-optic setup. The basic idea is just to bridge between the controller board and the motor drivers with optical fiber. To make this happen, a couple of signals need to be transmitted: pulse and direction. They’ve set the system up so that it can be chained as well. Serializing the data, Manchester encoding it for transmission, and decoding it on reception is handled by CPLDs for speed and reliability.
The team has been working on this project for a while now. If you’d like some more background you can check out their original design ideas. Design files from this released version are up on GitHub. A proposed improvement is to incorporate bi-directional communications. Bi-directional comms would allow data like limit-switch status to be communicated back from the machine to the controller over fiber.
This optical interface is in service of an open-source plasma cutter design, which is pretty cool in itself. And if the IRNAS group sounds familiar to you, that may be because we recently ran a story on their ambitious gigabit ethernet-over-lightbeam project.
Researchers at University College London successfully transferred data over an optical transmission system at a rate of 1.125 Tb/s. That’s over ten times as fast as typical commercial optical systems, and thousands of times faster than the standard broadband connection. The study appeared in Scientific Reports and takes advantage of encoding techniques usually seen in wireless systems.
The prototype system uses fifteen channels on different wavelengths. Each channel used 256QAM encoding (the same as you see on cable modems, among other things). A single receiver recovers all of the channels together. The technology isn’t commercially available yet. It is worth noting that the experiment used a transmitter and receiver very close to each other. Future tests will examine how the system performs when there are hundreds or thousands of feet of optical fiber between them.
Continue reading “Suddenly, 4G Feels Slow”
[Peter] has finished up his fiber optic microscope light source. When we last visited [Peter] he created a dimmer circuit for a 10 watt LED. That LED driver has now found its final home in [Peter’s] “Franken-ebay scope”, a stereo microscope built from parts he acquired over several years. Stereo microscopes scopes like these are invaluable for working on surface mount parts, or inspecting PCB problems. [Peter] had the fiber optic ring and whip, but no light source. The original source would have been a 150W Halogen lamp. The 10 watt led and driver circuit was a great replacement, but he needed way to interface the LED to the fiber whip. Keeping the entire system cool would be a good idea too.
This was no problem for [Peter], as he has access to a milling machine. He used an old CPU heat sink from his junk box as the base of the light source. The heat sink was drilled and tapped for the LED. The next problem was the actual fiber whip interface. For this, [Peter] milled a custom block from aluminum bar stock. The finished assembly holds the LED, driver, and the fiber whip. A sheet metal bracket allows the entire assembly to be mounted on the microscope’s post. We have to admit, if we were in [Peter’s] place, we would have gone with a cheap LED ring light. However, the end result is a very clean setup that throws a ton of light onto whatever [Peter] needs magnified.
Continue reading “Building an LED Source for a Fiber Optic Ring Light”
If you want to go high bandwidth, fiber optics is the way to go. From trans-oceanic cables to the yet-unseen ‘fiber to every home,’ fiber optics allows a lot more bandwidth than a copper cable. In low-bandwidth applications, fiber optic cable transmits data using one color of light. There’s a way to get more bandwidth out of a fiber optic cable, as [Shahriar] found out while experimenting with an RGB LED.
For his experiment, [Shahriar] used a BlinkM programmable RGB LED and a Sparkfun color sensor. In fiber optic lines with one light, it is possible to send many simultaneously using PWM, but noise becomes a problem at high data rates. Using an RGB LED, [Shahriar] sends three levels of Red, Green, and Blue to transmit 9 bits at a time – perfect for sending a byte with a parity check in one quick light burst.
[Shahriar]’s technique is exactly how the pros pump massive amounts of data through a single fiber optic cable. All the tools, code, and MATLAB functions are available on [Shahriar]’s site, ready to be used by anyone wanting to experiment for themselves.
In the video after the break, [Shahriar] breaks everything down, including the tools, theory, and actual circuits. It’s an amazing video demo, so thorough we’re wondering if [Shahriar] has any teaching ambitions.
Continue reading “Color multiplexing through fiber optics”
[Garrett] over at MaceTech was approached by a friend who needed a light-up mohawk installed on a Viking helmet, and he needed it ASAP.
Now, [Garrett] does tons of work with LEDs but it’s not every day you are asked to construct a sound-responsive LED mohawk. He had all sorts of LEDs and other bits on hand, but finding the fiber optics that would make up the mohawk itself took a bit of time.
After a bit of searching, he located some cheap bulk fiber optic toy wands, and got busy cutting them apart to remove the fiber bundles. The fibers were glued into a laser cut plastic assembly, where they were paired with a handful of OctoBrite CYANEA modules [Garrett] had on hand. He bought a handful of components from SparkFun, including an Arduino Pro Mini to control the device, as well as an electret mic and graphic equalizer chip to handle the audio input/filtering.
He wrapped up the code portion of the mohawk and handed it off to his friend, who says that the “helmet is +99 to epic awesomeness”, which sounds like a ringing endorsement to us.
Check out the video below to see the fiber optic mohawk helmet in action.
Continue reading “Awesome fiber optic LED Viking helmet”
There’s something calming about looking up into the night sky and seeing an array of shining stars off in the distance. [Marou] is a big fan of stargazing, but sometimes conditions are not optimal, so he decided to bring the stars inside.
His idea was to build a ceiling lamp that didn’t bask the room with light, but rather one that reproduced the peaceful twinkle of the night sky. He covered a wooden table with dark fabric and drilled a ton of tiny holes into the surface. He fitted the holes in the table with two big bundles of optical fibers since one bundle couldn’t quite cover the entire thing.
To light the cables, he built a pair of 4-LED illuminators, which contain red, blue, green, and white LEDs. Each light source is controlled via an Arduino which takes its direction from [Marou’s] infrared remote.
While the idea isn’t new, the implementation is pretty cool. At first we were expecting a small lamp, but anchoring an entire table to the ceiling as a light panel is definitely something we hadn’t seen before.
If you want to build something similar in your own living room, [Marou’s] Arduino code is free for the taking.
What do you do with 100 player piano rolls but no player piano? You come up with a way to digitize the information for MIDI playback. The rolls have 90 columns worth of holes, 88 for the keys and two more for pedals. Voids in the paper cause a note or pedal to be played, so an optical sensor can be used to transform the analog data into digital information. Simple enough, you’ll just need 90 sensors. But this brings up quite an alignment issue. The solution is to use fiber optic cable to position the IR light source in a hand-made 0.2″ spaced jig. At least the spacing meshes nicely with standard 0.1″ protoboard, which is what was used for mounting the sensors.