Tearing Down A Mysteriously Cheap $5 Fiber Optic To Cable TV Adapter

In his regular browsing on AliExpress, [Ben Jeffrey] came across something he didn’t understand—a $5 fiber optic to RF cable TV adapter. It was excessively cheap, and even more mysteriously, this thing didn’t even need power. He had to know how it worked, so he bought one and got down to tinkering with it.

Inside the device in question.

[Ben] needed some hardware to test the device with, so he spent $77 on a RF-to-fiber converter and a cheap composite-to-RF modulator so he could test the $5 fiber-to-RF part. A grand expenditure to explore a $5 device, but a necessary sacrifice for the investigation. Once [Ben] hooked up a fiber optic signal to the converter, he was amazed to see it doing its job properly. It was converting the incoming video stream to RF, and it could readily be tuned in on a TV, where the video appeared clean and true.

It was disassembly that showed how simple these devices really are. Because they’re one-way converters, they simply need to convert a changing light signal into an RF signal. Inside the adapter is a photodiode which picks up the incoming light, and with the aid of a few passives, the current it generates from that light becomes the RF signal fed into the TV. There’s no need for a separate power source—the photodiode effectively works like a solar panel, getting the power from the incoming light itself. The part is ultimately cheap for one reason—there just isn’t that much to it!

It’s a neat look at something you might suspect is complex, but is actually very simple. We’ve explored other weird TV tech before, too, like the way Rediffusion used telephone lines to deliver video content. Video after the break.

A map of the United States showing a series of interconnected lines in white, red, orange, yellow, and green to denote fiber optic and electrical transmission lines. Dots of white, orange, and yellow denote the location of the data centers relative to nearby metropolitan centers.

NREL Maps Out US Data Infrastructure

Spending time as wee hackers perusing the family atlas taught us an appreciation for a good map, and [Billy Roberts], a cartographer at NREL, has served up a doozy with a map of the data center infrastructure in the United States. [via LinkedIn]

Fiber optic lines, electrical transmission capacity, and the data centers themselves are all here. Each data center is a dot with its size indicating how power hungry it is and its approximate location relative to nearby metropolitan areas. Color coding of these dots also helps us understand if the data center is already in operation (yellow), under construction (orange), or proposed (white).

Also of interest to renewable energy nerds would be the presence of some high voltage DC transmission lines on the map which may be the future of electrical transmission. As the exact location of fiber optic lines and other data making up the map are either proprietary, sensitive, or both, the map is only available as a static image.

If you’re itching to learn more about maps, how about exploring why they don’t quite match reality, how to bring OpenStreetMap data into Minecraft, or see how the live map in a 1960s airliner worked.

Cheap Fiber Optic Wand Toy Becomes Tiny Weird Display

If you’ve ever seen those cheap LED fiber optic wands at the dollar store, you’ve probably just thought of them as a simple novelty. However, as [Ancient] shows us, you can turn them into a surprisingly nifty little display if you’re so inclined.

The build starts by removing the fiber optic bundle from the wand. One end is left as a round bundle. At the other end, the strands are then fed into plastic frames to separate them out individually. After plenty of tedious sorting, the fibers are glued in place in a larger rectangular 3D-printed frame, which holds the fibers in place over a matrix of LEDs. The individual LEDs of the matrix light individual fibers, which carry the light to the round end of the bundle. The result is a tiny little round display driven by a much larger one at the other end.

[Ancient] had hoped to use the set up for a volumetric display build, but found it too fragile to be fit for purpose. Still, it’s interesting to look at nonetheless, and a good demonstration of how fiber optics work in practice. As this display shows, you can have two glass fibers carrying completely different wavelengths of light right next to each other without issue.

We’ve featured some other great fiber optic hacks over the years, like this guide on making your own fiber couplings. Video after the break.

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Hackaday Links: August 4, 2024

Good news, bad news for Sun watchers this week, as our star launched a solar flare even bigger than the one back in May that gave us an amazing display of aurora that dipped down into pretty low latitudes. This was a big one; where the earlier outburst was only an X8.9 class, the one on July 23 was X14. That sure sounds powerful, but to put some numbers to it, the lower end of the X-class exceeds 10-4 W/m2 of soft X-rays. Numbers within the class designate a linear increase in power, so X2 is twice as powerful as X1. That means the recent X14 flare was about five times as powerful as the May flare that put on such a nice show for us. Of course, this all pales in comparison to the strongest flare of all time, a 2003 whopper that pegged the needle on satellite sensors at X17 but was later estimated at X45.

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Properly Pipe Laser Light Around With Homebrew Fiber Couplings

It’s a rare person who can pick up a cheap laser pointer and not wield it like a lightsaber or a phaser, complete with sound effects. There’s just something about the “pew-pew” factor that makes projecting a laser beam fun, even if it’s not the safest thing to do, or the most efficient way to the light from one place to another.

We suspect that [Les Wright] has pew-pewed his way through more than a few laser projects in his lab, including his latest experiments with fiber coupling of lasers. The video below is chock full of tips on connecting cheap communications-grade fiber assemblies, which despite their standardized terminations aren’t always easy to use with his collection of lasers. Part of the challenge is that the optical fiber inside the cladding is often very small — as few as 9 microns. That’s a small target to hit without some alignment help, which [Les] uses a range of hacks to accomplish.

The meat of the video demonstrates how to use a cheap fiber fault locator and a simple optical bench setup to precisely align any laser with an optical fiber. A pair of adjustable mirrors allow him to overlap the beams of the fault locator and the target laser precisely. The effects can be interesting; we had no idea comms-grade fiber could leak as much light through the cladding as this, and the bend-radius limits are pretty dramatically illustrated. [Les] teases some practical sensing applications for this in a follow-up video, which we’re looking forward to.

Looking for more laser fun with your remaining eye? Check out [Marco Reps] teardown of a 200-kW fiber laser.

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Sorry, Your Internet Connection Is Slow

How fast is your Internet connection? The days of 56K modems are — thankfully — long gone for most of us. But before you get too smug with your gigabit fiber connection, have a look at what researchers from the Network Research Institute in Japan have accomplished. Using a standard diameter fiber, they’ve moved data at a rate of 1 petabit per second.

The standard fiber has four spatial channels in one cladding. Using wavelength division multiplexing, the researchers deployed a total of 801 channels with a bandwidth over 20 THz. The fiber distance was over 50 km, so this wasn’t just from one side of a lab to another. Well if you look at the pictures perhaps it was, but with big spools of fiber between the two lab benches. The project uses three distinct bands for data transmission with 335 channels in the S-band, 200 channels in the C-band, and 266 channels in the L-band.

To put this into perspective, a petabit — in theory — could carry a million gigabit Ethernet connections if you ignore overhead and other losses. But even if that’s off by a factor of 10 it is still impressive. We can’t imagine this will be in people’s homes anytime soon but it is easy to see the use for major backhaul networks that carry lots of traffic.

We are still amazed that we’ve gone from ALOHA to 2.5-gigabit connections. Although the Raspberry Pi can’t handle even a fraction of the bandwidth, you can fit it with a 10-gigabit network card.

A fusion splicer being used to repair an optical fiber

Using A Fusion Splicer To Repair A Samsung TV’s Cable

Some Samsung TVs come with a system called One Connect, where all external cabling is connected to a separate box so that only one small signal cable goes to the TV. In some versions, the cable linking the TV with its Connect Box is a pure fiber optic cable that’s nearly transparent and therefore easy to hide.

Thin fiber optic cables are fragile however; when [Elecami Wolf] got one of these TVs for a very low price it turned out that this was because its One Connect cable had snapped. Replacement cables are quite expensive, so [Elecami Wolf] went on to investigate the inner workings of the fiber optic cable and figured out how to repair a broken one.

The cable consists of four pairs of plastic-coated glass fibers, which are attached to receivers and transmitters inside the thick connectors on either end. Repairing the cable required two things: figuring out which fibers should connect to each other, and a reliable way of connecting them together.

The first was difficult enough: a simple 1:1 connection didn’t work, so it took a bit of work to figure out the correct connection setup. One clever trick was pointing a camera at a working cable and comparing the flashing lights at each end; this helped to identify the right order for two of the four pairs. For the other two, a combination of reverse-engineering the electronic circuits and some systematic trial-and-error yielded a complete wiring diagram.

For the second part, [Elecami Wolf] called on a fiber optic expert who lent him a fusion splicer. This is a rather neat piece of equipment that semi-automatically brings two pieces of fiber together and welds them with an electric arc. Once this was complete, it was a matter of covering the splices to protect them from sharp bends, and the fancy TV was working again.

Although not everyone will have access to a multi-mode fusion splicer machine, [Elecami Wolf]’s videos provide fascinating insights into the workings of modern fiber-optic based consumer electronics. This might be the first fiber-optic splicing attempt we’ve seen; but if you’re trying to hook up an optical fiber to your circuit, this ball lens setup is a neat trick.

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