An Illuminating Look At A Wolf 5151 Light Source

May 23, 2022 by Tom Nardi 8 Comments

While originally designed to put light where the sun don’t shine for medical purposes, [Nava Whiteford] says the Wolf 5151 Xenon endoscopic light source also works well for microscopy and general optical experiments, especially since you can get them fairly cheap on the second hand market. His cost just $50 USD, which is a steal when you consider a replacement for its 300 watt Olympus-made bulb will run you about 200 bucks alone.

That said, [Nava] recently moved on to a more compact light source, and figured that was a good enough excuse to crack open the Wolf 5151 and see what makes it tick. In this particular post he’s just looking at the optical side of things, which is arguably the most interesting aspect of the device. Helpfully, the whole assembly is mounted to its own sled of sorts that can be pulled from the light source for a closer examination.

Beyond that expensive bulb we mentioned earlier, there’s a thick piece of what appears to be standard plate glass being used as an IR and UV filter. [Nava] suspects this component is responsible for keeping the rest of the optics from overheating, which is backed up by the fact that the metal plate its mounted to appears to feature a K-type thermocouple to keep an eye on its operating temperature. Forward of that is a unique aspheric lens that features a rough spot to presumably scatter the light at the center of the beam.

Our vote for the most fascinating component has to go to the Neutral Density (ND) filter, which is used to control the intensity of the light. In a more pedestrian light source you could just dim the bulb, but in this case, the Wolf 5151 uses a metal disk with an array of holes drilled into it. By rotating the disc with a DC motor, the lens can be variably occluded to reduce the amount of light that reaches the aperture, which connects to the fiber cable.

While it’s perhaps no surprise the build quality of this medical gear is considerably beyond the commercial gadgets most of us get to play with, it still doesn’t hold a candle (no pun intended) to the laser module pulled from a Tornado jet fighter.

Knowing Your Place: The Implications Of GPS Spoofing And Jamming

May 23, 2022 by Maya Posch 30 Comments

Artificial satellites have transformed the world in many ways, not only in terms of relaying communication and for observing the planet in ways previously inconceivable, but also to enable incredibly accurate navigation. A so-called global navigation satellite system (GNSS), or satnav for short, uses the data provided by satellites to pin-point a position on the surface to within a few centimeters.

The US Global Positioning System (GPS) was the first GNSS, with satellites launched in 1978, albeit only available to civilians in a degraded accuracy mode. When full accuracy GPS was released to the public under the 1990s Clinton administration, it caused a surge in the uptake of satnav by the public, from fishing boats and merchant ships, to today’s navigation using nothing but a smartphone with its built-in GPS receiver.

Even so, there is a dark side to GNSS that expands beyond its military usage of guiding cruise missiles and kin to their target. This comes in the form of jamming and spoofing GNSS signals, which can hide illicit activities from monitoring systems and disrupt or disable an enemy’s systems during a war. Along with other forms of electronic warfare (EW), disrupting GNSS signals form a potent weapon that can render the most modern avionics and drone technology useless.

With this in mind, how significant is the threat from GNSS spoofing in particular, and what are the ways that this can be detected or counteracted?

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A fusion splicer being used to repair an optical fiber

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

May 23, 2022 by Robin Kearey 31 Comments

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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Lotus 123 For Linux Is Like A Digital Treasure Hunt

May 23, 2022 by Al Williams 84 Comments

Ever hear of Lotus 123? It is an old spreadsheet program that dominated the early PC market, taking the crown from incumbent Visicalc. [Tavis Ormandy] has managed to get the old software running natively under Linux — quite a feat for software that is around 40 years old and was meant for a different operating system. You can see the results in glorious green text on a black screen in the video below.

If you are a recent convert to Linux, you might not remember what a pain it was “in the old days” to install software. But in this case, it is even worse since the software isn’t even for Linux. The whole adventure started with [Tavis] wanting to find the API kit used to add plugins to Lotus. In theory, you could use it to add modern features to the venerable spreadsheet program.

The $395 software development kit wasn’t very common and there was also a Unix version of Lotus 123, but no one seemed to have a copy of that. [Tavis] eventually found someone who ran a circa-1990 BBS and had the data on tape. Turned out there was a hot copy of the SDK that he was able to use. But he noticed something else in the BBS’s list of files: the long-lost Unix version of Lotus!

An investigation found the installer used TD0 files which took some research. Luckily, a utility exists that can convert these to raw disk images. Inside was a very large object file. Apparently, in the days without dynamic loading, that object would be linked with plug in modules to install them.

The object file had all of its debugging information intact which shed a lot of light on the program’s internal operations. The old executables used COFF format but it is possible to relink it to an ELF file. Of course, it isn’t just that easy. [Tavis] wrote a small program to remove the old-style Unix system calls so they could be rerouted to Linux system calls. Some calls just pass through, but others need some translation due to differences in things like structure layout, sizes, and alignment.

In the end, it all worked but didn’t have a valid license. However, [Tavis] felt like since he did have a license and the software is abandoned, he was within his rights to crack the license check.

We are well-known abusers of spreadsheets around here. Of course, we aren’t the only ones.

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