Mystery HP Gear Teardown

October 22, 2021 by Al Williams 6 Comments

What’s round, has what looks like a vacuum tube in the center, and was made in the 1950s by HP? We don’t know either, but [The Signal Path] restored one and shows us this mystery instrument in a recent video that you can see below. We aren’t going to spoil the surprise over what the device is, but we will share that he does reveal what it is very early in the video, so there’s not much of a tease.

We will, however, give you a few hints. Looking at it, you can guess that it is meant for high voltage use and, in fact, it is rated for up to 25 kV. We’ll also drop the hint that it is made for use with AC, not DC. The shape of the plug at the end of the wire is also a clue, we think.

There isn’t much inside the unusual round case (another clue, by the way), but there are some vintage parts we haven’t seen in quite awhile. One last clue: Why is there a metal rod and ball sticking out of one side of the device?

Honestly, the insides are a bit underwhelming so unlike some teardown videos we’ve seen, the real star of this video is the unusual device more so than its inner workings. If you have a hankering for a more sophisticated HP exploration, check out the HP3458A repair we covered earlier. Or go old school and peek inside an HP 150A.

Continue reading “Mystery HP Gear Teardown” →

Calculate Like It’s 1989 With This HP15C Emulator

August 31, 2021 by Dan Maloney 41 Comments

Back in the day, your choice of calculator said a lot about your chops, and nothing made a stronger statement than the legendary Hewlett-Packard Voyager series of programmable calculators. From the landscape layout to the cryptic keycaps to the Reverse Polish Notation, everything about these calculators spoke to a seriousness of purpose.

Sadly, these calculators are hard to come by at any price these days. So if you covet their unique look and feel, your best bet might be to do like [alxgarza] and build your own Voyager-series emulator. This particular build emulates the HP15C and runs on an ATMega328. Purists may object to the 192×64 LCD matrix display rather than the ten-digit seven-segment display of the original, but we don’t mind the update at all. The PCB that the emulator is built on is just about the right size, and the keyboard is built up from discrete switches that are as satisfyingly clicky as the originals. We also appreciate the use of nothing but through-hole components — it seems suitably retro. The video below shows that the calculator is perfectly usable without a case; a 3D-printed case is available, though, as is an overlay that replicates the keypad of the original.

We’ve seen emulators for other classic calculators of yore, including Sinclair, Texas Instruments, and even other HP lines. But this one has a really nice design that gets us going.

Continue reading “Calculate Like It’s 1989 With This HP15C Emulator” →

Boat Anchor Nixie Clock Plays The Cold Warrior Role Convincingly

April 27, 2021 by Dan Maloney 13 Comments

The early Cold War years may have been suffused with existential dread thanks to the never-ending threat of nuclear obliteration, but at least it did have a great look. Think cars with a ton of chrome, sheet steel toys with razor-sharp edges, and pretty much the entire look of the Fallout franchise. And now you can add in this boat anchor of an electromechanical Nixie clock, too.

If [Teti]’s project looks familiar, perhaps it’s because the build was meant as an homage to the test equipment of yore, particularly some of the sturdier offerings from Hewlett-Packard. But this isn’t some thrift store find that has been repurposed; rather, the entire thing, from the electronics to the enclosure, is scratch built. The clock circuit is based on 4000-series CMOS chips and the display uses six IN-1 Nixies. Instead of transistors to drive the tubes, [Teti] chose to use relays, which in the video below prove to be satisfyingly clicky and relaxing. Not relaxing in any way is the obnoxious alarm, which would be enough to rouse a mission control officer dozing in his bunker. [Teti] has a blog with more details on the build, the gem of which is information on how he had the front panel so beautifully made.

We can’t say enough about the fit and finish of this one, as well as the functionality. What’s even more impressive is that this was reportedly [Teti]’s first project like this. It really puts us in mind of some of the great 6502 retrocomputer builds we’ve been seeing lately.

Continue reading “Boat Anchor Nixie Clock Plays The Cold Warrior Role Convincingly” →

This Expedient Microfiche Reader Illuminates Retro Datasheets

December 20, 2020 by Dan Maloney 22 Comments

You have to be of a certain vintage to remember doing research on microfilm and microfiche. Before the age of mass digitization of public records, periodicals, and other obscure bits of history, dead-tree records were optically condensed onto fine-grain film, either in roll form or as flat sheets, which were later enlarged and displayed on a specialized reader. This greatly reduced the storage space needed for documents, but it ended up being a technological dead-end once the computer age rolled around.

This was the problem [CuriousMarc] recently bumped into — a treasure trove of Hewlett-Packard component information on microfiche, but no reader for the diminutive datasheets. So naturally, he built his own microfiche reader. In a stroke of good luck, he had been gifted a low-cost digital microscope that seemed perfect for the job. The scope, with an HD camera and 5″ LCD screen, was geared more toward reflective than transmissive use, though, so [Marc] had trouble getting a decent picture of the microfiches, even with a white paper backing.

Version 2.0 used a cast-off backlight, harvested from a defunct DVD player screen, as a sort of light box for the stage of the microscope. It was just about the perfect size for the microfiches, and the microscope was able to blow up the tiny characters as well as any dedicated microfiche reader could, at a fraction of the price. Check out the video below for details on the build, as well as what [Marc] learned from the data sheets about his jackpot of HP parts.

With the wealth of data stored on microforms, we’re surprised that we haven’t seen any readers like this before. We have talked about microscopic wartime mail, though.

Continue reading “This Expedient Microfiche Reader Illuminates Retro Datasheets” →

Retro Calculator Design Has Creative Tactile Touchscreen

October 18, 2020 by Lewin Day 25 Comments

We’ve all heard it a thousand times – they don’t make ’em like they used to. Sometimes, that’s for good reason, but there is a certain build quality to electronics of the mid-20th century that is hard to find in hardware today. This inspires great nostalgia and dedication in some, like [Michael Park], who set out to build a calculator reminiscent of the best HP designs from yesteryear.

The scissor mechanism allows the touch screen to move linearly and activate the tactile switch without twisting, no matter where along its surface it is pressed.

One of the major factors for [Michael] was the great feel of the keys on these classic units. Wanting to experiment with different layouts without a lot of rewiring, the idea of keys with individual displays became attractive. Existing parts on the market were prohibitively expensive, however. Instead, [Michael] used a single touchscreen with a switch mounted underneath to provide tactile feedback with a nifty scissor-arm guide mechanism. Combined with individual see-through plastic overlays, the MP-29 has a fully reconfigurable pad of 30 keys with dynamically updatable labels.

It’s a creative choice, and one that looks highly satisfying to use. It has all the tactile benefits of individual keys, both in the keypresses and being able to navigate the keypad without looking. Combined with the benefit of reconfigurable keys thanks to the touch screen underneath, it’s a great way to build a user-interface.

The rest of the calculator design closely mimics the HP-29, though [Michael] is also experimenting with alternative layouts too. There are plenty of religious wars in the calculator community over usability, after all – mostly over which side of the pad has the arithmetic functions.

We’ve lamented the demise of the standalone calculator recently; with so many smart devices around, it’s hard to see it making a major comeback anytime soon. Of course, if you’re opinionated on the topic, sound off in the comments below. Video after the break.

Continue reading “Retro Calculator Design Has Creative Tactile Touchscreen” →

Retrotechtacular: The $5,000 40 Pound HP Classroom Computer

October 2, 2020 by Al Williams 21 Comments

See if you can talk your local school district into buying a computer that costs about $5,000 and weighs 40 pounds. That was HP’s proposition to schools back in 1968 so really it is more like $35,000 today. The calculator had a CRT display for the RPN stack that you could mirror on a big screen. You could also get a printer or plotter add-on. Pretty hot stuff for the ’60s.

The 1970 videos promoting the HP 9100, posted by the [Computer History Archive Project], shows something we’d think of as a clunky calculator, although by the standards of the day it was a pretty good one with trig functions and a crude programming capability.

Continue reading “Retrotechtacular: The $5,000 40 Pound HP Classroom Computer” →

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” →