An Old Calculator Lives Again

August 24, 2020 by Al Williams 42 Comments

There was a time when any electronics student would have a slide rule hanging off their belt. By the 1970s, the slide rule changed over to an electronic calculator which was a pricy item. Today you can buy calculators at the dollar store. [JohnAudioTech] pulled out an old Radio Shack vacuum fluorescent display (VFD) calculator and found it didn’t work. Obviously, that means it is time to open it up.

It is fun to see one of these old devices opened up again. Consumer electronics with big through-hole ICs! Troubleshooting the device wound up being anti-climatic, as a broken wire to the battery compartment explained the whole thing.

As a teardown, though, this is a fun video. Not only are all the parts through-hole, but the PCB is clearly a manual layout with serpentine traces flowing across the board like some sort of art piece. Continue reading “An Old Calculator Lives Again” →

Gaze Inside The Valve Index VR Headset In Detailed Teardown

August 13, 2020 by Donald Papp 9 Comments

Valve’s unique multilayer lenses are far thinner than one might expect.

Want to see what exactly is inside the $500 (headset only price) Valve Index VR headset that was released last summer? Take a look at this teardown by [Ilja Zegars]. Not only does [Ilja] pull the device apart, but he identifies each IC and takes care to point out some of the more unique hardware aspects like the fancy diffuser on the displays, and the unique multilayered lenses (which are much thinner than one might expect.)

[Ilja] is no stranger to headset hardware design, and in addition to all the eye candy of high-res photographs, provides some insightful commentary to help make sense of them. The “tracking webs” pulled from the headset are an interesting bit, each is a long run of flexible PCB that connects four tracking sensors for each side of the head-mounted display back to the main PCB. These sensors are basically IR photodiodes, and detect the regular laser sweeps emitted by the base stations of Valve’s lighthouse tracking technology. [Ilja] also gives us a good look at the rod and spring mechanisms seen above that adjust distance between the two screens.

Want more? [Ilja] also has a gallery of high-resolution images available for those you who fancy a closer look. Also, if you missed it, we covered an examination of the Index’s optical design as part of everything you probably didn’t know about field of view in head-mounted displays.

[via Twitter]

Teardown: Orthofix SpinalStim

August 5, 2020 by Tom Nardi 59 Comments

If you’ve ever had a particularly nasty fracture, your doctor may have prescribed the use of an electronic bone growth stimulator. These wearable devices produce a pulsed electromagnetic field (PEMF) around the bone, which has been shown to speed up the natural healing process in a statistically significant number of patients. That’s not to say there isn’t a debate about how effective they actually are, but studies haven’t shown any downsides to the therapy, so it’s worth trying at least.

When you receive one of these devices, it will be programmed to only operate for a certain amount of time or number of sessions. Once you’ve “used up” the bone stimulator, it’s functionally worthless. As you might imagine, there’s no technical reason this has to be the case. The cynic would say the only reason these devices have an expiration date on them is because the manufacturer wants to keep them from hitting the second hand market, but such a debate is perhaps outside the scope of these pages.

The Orthofix SpinalStim you’re seeing here was given to me by a friend after their doctor said the therapy could be cut short. This provided a somewhat rare opportunity to observe the device before it deactivated itself, which I’d hoped would let me take a closer look at how it actually operated.

As you’ll soon see, things unfortunately didn’t work out that way. But that doesn’t mean the effort was fruitless, and there may yet be hope for hacking these devices should anyone feel like taking up the challenge.

Continue reading “Teardown: Orthofix SpinalStim” →

Inside A $30,000 8 GHz Scope

July 29, 2020 by Al Williams 20 Comments

One of the best things about the Internet — especially the video part — is that you can get exposed to lots of things you might otherwise not be able to see. Take oscilloscopes, for example. If you were lucky, you might have one or two really nice instruments at work and you certainly weren’t going to be allowed to tear them open if they were working well. [The Signal Path], as a case in point, tears down a $30,000 MSO6 8 GHz oscilloscope.

Actually, the base price is not quite $30,000 but by the time you outfit one, you’ll probably break the $30K barrier. Compared to the scopes we usually get to use, these are very different. Sure, the screens are larger and denser, but looking at the circuit boards they look more like some sort of high-end computer than an oscilloscope. Of course, in a way, that’s exactly what it is.

Continue reading “Inside A $30,000 8 GHz Scope” →

Vintage Instrument Gets Modern Replacement For Unobtainium Parts

July 10, 2020 by Dan Maloney 13 Comments

One of the best parts about Hackaday is how much you learn from the projects that people tackle, especially when they are repairs on old gear with unknown failure modes and potentially multiple problems. By the same token, the worst part about Hackaday is seeing what other people are capable of and knowing that you’ve got a long way to go to catch up to them.

A case in point is [Curious Marc]’s recent repair of an old pulse generator. The instrument in question is an H-P 8082A, a device from a time when H-P was a place where “good engineers managed by even better engineers [wanted] to help other engineers,” as [Marc] so eloquently puts it. The instrument was capable of 250 MHz output with complete control over the amplitude, frequency, duty cycle, and rising and falling edge geometry of the pulses, in addition to being able to output double pulses. For an all-analog instrument made in 1974, it was in decent shape, and it still powered up and produced at least the square wave output. But [Marc]’s exploration revealed a few problems, which are detailed and partially addressed in the first video below.

In part two [Marc] goes after the problem behind the pulse delay function. He traced it to a bad IC, which was bad news since it was a custom H-P part using emitter-coupled logic (ECL) to achieve the needed performance that can no longer be sourced. So naturally, [Marc] decided to replace the chip with a custom circuit. The design and simulation of the circuit are detailed in part two, while the non-trivial details of designing a PCB to handle the high-speed signals take up most of part three. We found the details on getting the trace impedance just right fascinating.

In the end, [Marc]’s pulse generator was salvaged. It’ll go into service helping him probe the mysteries of vintage electronics from the Apollo era, so we’re looking forward to seeing more about this great old instrument.

Continue reading “Vintage Instrument Gets Modern Replacement For Unobtainium Parts” →

Unrolling The Mystery Inside An Aluminum Electrolytic Capacitor

July 1, 2020 by Roger Cheng 4 Comments

When we remove the enclosure of modern electronics, we see a lot of little silvery cylinders wrapped with heat shrink plastic. These aluminum electrolytic capacitors are common residents on circuit boards. We may have cut one open to satisfy our curiosity of what’s inside, but that doesn’t necessarily mean we understood everything we saw. For a more detailed guided tour, follow [TubeTime]’s informative illustrated Twitter thread.

Electronics beginners are taught the basic canonical capacitor: two metal plates and an insulator separating them. This is enough to understand the theory of capacitor operation, but there were hints the real world is not quite that simple. We don’t even need to disassemble an electrolytic capacitor to get our first hint: these cylinders have markings to indicate polarity, differentiating them from the basic capacitor which is symmetric and indifferent to polarity. Once taken apart and unrolled, we would find two thin aluminum foils separated by a sheet of paper. It would be tempting to decide the foil were our two plates and the paper is our insulator, except for the fact those two metal plates are different sizes further deviating from the basic capacitor.

Electronics veterans know the conductor–insulator–conductor pattern is not foil–paper–foil, but actually foil–oxide–electrolyte. But there is more to [TubeTime]’s tour than this answer, which includes pictures of industrial machinery, a side adventure in electrolytic chemistry using a tiny glass beaker, concluding with links to more information. And once armed with knowledge, we can better understand why electrolytic capacitors don’t necessarily need to be replaced in old equipment and appreciate them within the larger history of capacitors context.

Comparing Bare Silicon On Two Game Boy Audio Chips

June 27, 2020 by Al Williams 2 Comments

We always look forward to a new blog post by [Ken Shirriff] and this latest one didn’t cure us of that. His topic this time? Comparing two Game Boy audio chips. People have noticed before that the Game Boy Color sounds very different than a classic Game Boy, and he wanted to find out why. If you know his work, you won’t be surprised to find out the comparison included stripping the die out of the IC packaging.

[Ken’s] explanation of how transistors, resistors, and capacitors appear on the die are helpfully illustrated with photomicrographs. He points out how resistors are notoriously hard to build accurately on a production IC. Many differences can affect the absolute value, so designs try not to count on exact values or, if they do, resort to things like laser trimming or other tricks.

Capacitors, however, are different. The exact value of a capacitor may be hard to guess beforehand, but the ratio of two or more capacitor values on the same chip will be very precise. This is because the dielectric — the oxide layer of the chip — will be very uniform and the photographic process controls the planar area of the capacitor plates with great precision.

We’ve decapsulated chips before, and we have to say that if you are just starting to look at chips at the die level, these big chips with bipolar transistors are much easier to deal with than the fine and dense geometries you’d find even in something like a CPU from the 1980s.

We always enjoy checking in with [Ken]. Sometime’s he’s taking apart nuclear missiles. Sometimes he is repairing an old computer. But it is always interesting.