Ode To An AVO 8 Multimeter

October 27, 2020 by Jenny List 41 Comments

I’m moving, and in the process of packing all of my belongings into storage boxes to disappear into a darkened room for the next year. Perhaps I could become one of those digital nomads I hear so much about and post my Hackaday stories from a sun-kissed beach while goldfish shoals nibble at my toes. But here in a slightly damp British autumn, box after box of a lifetime’s immersion in tech needs sorting and directing. Why on earth did I hang on to three Philips N1500 VCR system video cassette recorders from the early 1970s! (Don’t worry, those have found a good home.)

Say Hello To An Old Friend Of Mine

As I was packing up my bench, I happened upon a multimeter. I have quite a few multimeters and this isn’t the first time I’ve written about these indispensable instruments, but this one’s a little special.

It’s a treasure from my youth, that most venerable of British test equipment: the AVO 8. This was the ubiquitous multimeter to be found in all manner of electrical and electronic workshops across most of the 20th century, and remains to this day one of the highest quality examples of its type.

It’s a relatively huge Bakelite box about 190mm x 170mm x 100mm in size, and it is instantly recognisable by its dual rotary selector switches and the window for viewing the needle, which forms a characteristic circular arc kidney shape.

The earliest ancestors of my meter appeared in the 1920s, and the first model 8 in the early 1950s. Mine is a Mk III that a penciled date on the inside of its meter movement tells me was made in November 1965 and which I bought reconditioned from Stewart of Reading in about 1991, but manufacture continued until the last Mk VIII rolled off the production line in 2008. It’s to my shame that my AVO is a bit dusty and that maybe I haven’t used it much of late, but as I picked it up all the memories of using it to fix dead TV sets and set up optimistic experiments in radio came flooding back. If there’s one instrument that connects me to the youthful would-be electronic engineer that I once was, then here it is. Continue reading “Ode To An AVO 8 Multimeter” →

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]

Reliving Heathkit’s Glory Days Through A Teardown And Rebuild

June 26, 2020 by Dan Maloney 10 Comments

In its heyday, the experience offered by the Heath Company was second to none. Every step of the way, from picking something out of the Heathkit catalog to unpacking all the parts to final assembly and testing, putting together a Heathkit project was as good as it got.

Sadly, those days are gone, and the few remaining unbuilt kits are firmly in the unobtanium realm. But that doesn’t mean you can’t tear down and completely rebuild a Heathkit project to get a little taste of what the original experience was like. [Paul Carbone] chose a T-3 Visual-Aural signal tracer, a common enough piece that’s easy to find on eBay at a price mere mortals can afford. His unit was in pretty good shape, especially for something that was probably built in the early 1960s. [Paul] decided that instead of the usual recapping, he’d go all the way and replace every component with fresh ones. That proved easier said than done; things have changed a lot in five decades, and resistors are a lot smaller than they used to be. Finding hookup wire to match the original was also challenging, as was disemboweling some of the electrolytic cans so they could be recapped. The finished product is beautiful, though — even the Magic Eye tube works — and [Paul] reports that the noise level is so low he wasn’t sure if turned it on at first.

We’ve covered the rise and fall of Heathkit, as well as their many attempted comebacks, including an inexplicable solder-free radio and the “world’s most reliable” clock. Looking at these offerings, we think [Paul] may be onto something here.

Popping The Hood On The Flux Beamo Laser Cutter

June 22, 2020 by Tom Nardi 27 Comments

While the K40 has brought affordable laser cutting to the masses, there’s no question that it took a lot of sacrifices to hit that sub-$400 price point. There’s a reason that we’ve seen so many upgrades and improvements made to the base model machine, but for the price it’s hard to complain. That being said, for users who don’t mind spending a bit more money for a more complete out-of-the-box experience, there are other options out there.

One of them is the beamo, from FLUX. [Frank Zhao] recently picked up one of these $1,900 USD laser cutters because he wasn’t thrilled with the compromises made on the K40. Specifically, he really liked the idea of the internal water cooling system. Oddly enough, something about using a garden hose and buckets of water to cool the laser seemed off-putting. Luckily for us, he’s got a technical eye and the free time necessary to do a teardown and objective analysis of his new toy.

The short version of the story is that [Frank] is not only happy with the results he’s getting, but finds the machine to be well designed and built. So if you’re looking for a rant, sorry. But what you will find is a methodical look at each subsystem of the beamo, complete with annotated pictures and the kind of technical details that Hackaday readers crave.

We especially like his attempts to identify parts which might be difficult to source in the future; it looks like the CO2 laser tube might be proprietary, but everything else looks fairly jellybean. That includes the Raspberry Pi 3B that’s running the show, and the off-the-shelf touch screen HDMI display used for the interface. [Frank] did note that FLUX was unwilling to give him the credentials to log into the Pi and poke around, but with direct access to the SD card, it’s not like that will stop anyone who wants to get in.

In a way, laser cutters are in a similar situation today to that desktop 3D printers were in a few years ago. The cheap ones cut so many corners that upgrades and fixes are almost a necessity, and building your own machine is often less expensive than buying a commercial offering with similar specs. While the beamo is still a bit too expensive for the average hobbyist, it’s good to see machines of this caliber are at least coming down out of the 5 figure range.

Just How Do Aircraft Transponders Work Anyway?

June 22, 2020 by Jenny List 32 Comments

Most of us will have a hazy idea of how radar works to detect aircraft by listening for reflected radio waves. And we’ll probably also know that while radar can detect aircraft, it’s not the most efficient or useful tool in the hands of an air traffic controller. Aircraft carry transponders so that those on the ground can have a clearer picture of the skies, as each one reports its identity, altitude, and position. [Yeo Kheng Meng] was lucky enough to secure a non-functioning aircraft transponder and do a teardown, and his write-up makes for interesting reading as he explains their operation before diving into the hardware.

The 1978 and 1979 date codes on the various integrated circuits and transistors identify it as having been made in 1979, so not having a CPU is not entirely unsurprising given its age. Instead this is a straightforward device that responds to pulse lengths of different timings with sequential bursts of data.

[Yeo Kheng] is mystified by the RF strip and associated components, which look to us like a typical crystal oscillator and frequency multiplier strip from that era, along with some screened boxes that probably contain cavity filters and given that there is also a high voltage power supply present, a tube RF power amplifier. GHz-capable semiconductors were quite exotic in the 1970s, while high-frequency tubes had by then a long history.

It’s evident that the tech behind aircraft transponders has moved on since this unit was built, but one thing’s certain. Hackers in 1978 would have had to go to a lot of work to listen to them and interpret the results, while here in the 21st century it’s something we do routinely.

Teardown: Nabaztag

May 26, 2020 by Jenny List 27 Comments

In 2020 there is nothing novel or exciting about an online device. Even the most capable models are designed to be unobrusive pucks and smart speakers; their function lies in what they do rather than in how they look. In 2005, an Internet connected device was a rare curiosity, a daring symbol of a new age: the “Internet of Things”!

Our fridges were going to suggest recipes based upon their contents, and very few people had yet thought of the implications of an always-on connected appliance harvesting your data on behalf of a global corporation. Into this arena stepped the Nabaztag (from the Armenian for “rabbit”), an information appliance in the form of a stylised French plastic rabbit that could deliver voice alerts, and indicate status alerts by flashing lights and moving its ears.

Continue reading “Teardown: Nabaztag” →

Hacking Apollo Hack Chat

April 20, 2020 by Dan Maloney 2 Comments

Join us on Wednesday, April 22 at noon Pacific for the Hacking Apollo Hack Chat with “CuriousMarc” Verdiell, Ken Shirriff, Mike Stewart, and Carl Claunch!

When President Kennedy laid down the gauntlet to a generation of scientists and engineers to land a man on the Moon before the close of the 1960s, he likely had little idea what he was putting in motion. The mission was dauntingly complex, the science was untested, and the engineering was largely untried. Almost everything had to be built from scratch, and entire industries were born just from the technologies that had to be invented to make the dream come true.

Chief among these new fields was computer science, which was barely in its infancy when the 1960s started. By the end of the decade and the close of the Space Race, computers had gone from room-filling, power-guzzling machines to something compact and capable enough to fly men to the Moon and back. The computers that followed all built on the innovations that came about as a result of Apollo, and investigating the computers of the era and finding out what made them tick is an important part of our technological culture.

That’s where this retrocomputing dream team came into play. Together, they’ve poked and prodded at every bit of hardware from the Space Race era they could find, including a genuine Apollo Guidance Computer (AGC) that was rescued from the trash. What’s more, they actually managed to restore it to working condition with a series of epic hacks and sheer force of will.

Marc, Ken, Mike, and Carl will stop by the Hack Chat to talk about everything that went into getting the AGC working again, along with anything else that pops up. Come ready to have your Apollo-era hardware itches scratched by the people who’ve been inside a lot of it, and who have seen first-hand what it took to make it to the Moon and back.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, April 22 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Continue reading “Hacking Apollo Hack Chat” →