Upgrading A Classic Function Generator

If you need an oscilloscope, function generator, or other piece of kit for your electronics workbench, there are plenty of modern options. Dropping $4,000 for a modern oscilloscope is nice if you have the money, but if you’d rather put it to better use there are great options that don’t cost a fortune. There are some addons that can turn a smartphone into an oscilloscope but one of the best values out there are older pieces of equipment from the 80s that still work great. You can even upgrade them with some more modern features too, like [NFM] did with this vintage function generator.

This function generator is an HP3325A and it is several decades old, so some work was needed just to restore it to original working condition. The cooling fan and capacitors all needed to be replaced, as well as a few other odds and ends. From there [NFM] set about adding one of the two optional upgrades available for this device, the high voltage output. This allows the function generator to output 40 volts peak-to-peak at 40 milliamps. While he did have an original version from HP, he actually had a self-made design produced that matches the function of the original.

Even if you don’t have this specific function generator, this guide goes into great details about the functioning of older equipment like this. Most of the parts are replaceable and upgrades aren’t completely out of the question like some modern equipment, and with the right care and maintenance these pieces of equipment could last for decades longer.

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

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.

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Cesium Clock Teardown, Or Quantum Physics Playground

Half the fun of getting vintage test equipment is getting to open it up. Maybe that’s even more than half of the fun. [CuriousMarc] got an HP 5061A Cesium clock, a somewhat famous instrument as the model that attempted to prove the theory of relativity. The reason? The clock was really the first that could easily be moved around, including being put on an airplane. You can watch the video below.

According to the video, you can simplify special relativity to saying that time slows down if you go fast — that is known as time dilation. General relativity indicates that time slows down with increasing gravity. Therefore, using airborne Cesium clocks, you could fly a clock in circles high up or fly at high speeds and check Einstein’s predictions.
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Dissecting China-Sourced Vintage HP 1970s ICs: Genuine Or Not?

While repairing a real-time clock module for a 1970s HP computer that had been damaged by its leaky internal battery, [CuriousMarc] began to suspect that maybe the replacement clock chips which he had sourced from a seller in China were the reason why the module still wasn’t working after the repairs. This led him down the only obvious path: to decap and inspect both the failed original Ti chip and the replacement chip.

The IC in question is the Texas Instruments AC5948N (along with the AC5954N on other boards), which originally saw use in LED watches in the 1970s. HP used this IC in its RTC module, despite it never having been sold publicly. This makes it even more remarkable that a Chinese seller had the parts in stock. As some comments on the YouTube video mention, back then there wasn’t as much secrecy around designs, and it’s possible someone walked out of the factory with one of the masks for this chip.

Whether true or not, as the video (also included after the break) shows, both the original 1970s chip and the China-sourced one look identical. Are they original stock, or later produced from masks that made their way to Asia? We’ll probably never know for sure, but it does provide an exciting opportunity for folk who try to repair vintage equipment.

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A Modern Take On A Piece Of Old Test Equipment

The HP 11947A is something of a footnote in the back catalogue of Hewlett Packard test equipment. An attenuator and limiter with a bandwidth in the megahertz rather than the gigahertz. It’s possible that few laboratories have much use for one in 2019, but it does have one useful property: a full set of schematics and technical documentation. [James Wilson] chose the device as the subject of a clone using surface mount devices.

The result is very satisfyingly within spec, and he’s run a battery of tests to prove it. As he says, the HP design is a good one to start with.   As a device containing only passive components and with a maximum frequency in the VHF range this is a project that makes a very good design exercise for anyone interested in RF work or even who wishes to learn a bit of RF layout. At these frequencies there are still a significant number of layout factors that can affect performance, but the effect of conductor length and  stray capacitance is less than the much higher frequencies typically used by wireless-enabled microcontrollers.

Patch, Or Your Solid State Drives Roll Over And Die

Expiration dates for computer drives? That’s what a line of HP solid-state drives are facing as the variable for their uptime counter is running out. When it does, the drive “expires” and, well, no more data storage for you!

There are a series of stages in the evolution of a software developer as they master their art, and one of those stages comes in understanding that while they may have a handle on the abstracted world presented by their development environment they perhaps haven’t considered the moments in which the real computer that lives behind it intrudes. Think of the first time you saw an SQL injection attack on a website, for example, or the moment you realised that a variable type is linked to the physical constraints of the number of memory locations it has reserved for it. So people who write software surround themselves with an armoury of things they watch out for as they code, and thus endeavour to produce software less likely to break. Firmly in that arena is the size of the variables you use and what will happen when that limit is reached.

Your Drive Is Good For About 3 Years And 9 Months

Sometimes though even developers that should know better get it wrong, and this week has brought an unfortunate example for the enterprise wing of the hardware giant HP. Their manufacturer has notified them that certain models of solid-state disk drives supplied in enterprise storage systems contain an unfortunate bug, in which they stop working after 32,768 hours of uptime. That’s a familiar number to anyone working with base-2 numbers and hints at a 16-bit signed integer in use to log the hours of uptime. When it rolls over the value will then be negative and, rather than the drive believing itself to be in a renewed flush of youth, it will instead stop working.

Egg on the faces of the storage company then, and an urgently-released patch. We suspect that if you own a stack of these drives you will already know about the issue and be nervously pacing the racks of your data centre.

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Where Did Pocket Computing Start?

A smartphone in 2019 is an essential piece of everyday equipment. Many of you are probably reading this page on one, and it will pack a very significant quantity of computing power into your hand. Pocket computing has a long history stretching back decades before the mass adoption of smartphones though, and Paleotronic has an interesting retrospective of that earlier history.

The piece starts with the Radio Shack PC-1, a rebadged Sharp with a calculator-style keyboard and a one-line alphanumeric LCD display, then continues through the legendary TRS-80 Model 100 to the era of the palmtop. It’s a difficult subject to cover in its entirety as there are so many milestones on the pocket computing path, but it’s an interesting read nevertheless as it successfully evokes the era when a 300 Baud connection via an acoustic coupler was a big deal. We might for example have mentioned the Atari Portfolio if only for its use by a young John Connor to scam an ATM in Terminator 2, and as any grizzled old sysadmin will tell you, there was a time when owning a Nokia Communicator might just save your bacon.

Of the classic pocket computing devices mentioned, only one has received significant coverage here. The TRS-80 model 100 still has a huge following, and among quite a few hacks featuring it we’ve seen one brought into the smartphone age by getting the ability to make a cellular connection.

TRS-80 Model 100 image: Jeff Keyzer from Austin, TX, USA [CC BY-SA 2.0]