Beyond The Basics: Exploring Exotic Scope Trigger Modes

December 20, 2023 by Al Williams 15 Comments

Will Rogers once said that veterinarians are the best doctors because their patients can’t tell them where it hurts. I’ve often thought that electronic people have a similar problem. In many cases, what’s wrong with our circuits isn’t visible. Sure, you can visually identify a backward diode, a bad solder joint, or a blown fuse. But you can’t look at a battery and see that it is dead or that a clock signal isn’t reaching some voltage. There are lots of ways to look at what’s really going on, but there is no substitute for a scope. It used to be hard for the average person to own a scope, but these days, it doesn’t require much. If you aren’t shopping for the best tech or you are willing to use it with a PC, oscilloscopes are quite affordable. If you spend even a little, you can now get scopes that are surprisingly capable with features undreamed of in years past. For example, many modern scopes have a dizzying array of triggering options. Do you need them? What do they do? Let’s find out.

I’ll be using a relatively new Rigol DHO924S, but none of the triggering modes are unique to that instrument. Sometimes, they have different names, and, of course, their setup might look different than my pictures, but you should be able to figure it out.

What is Triggering?

In simple terms, an oscilloscope plots time across the X-axis and voltage vertically on the Y-axis. So you can look at two peaks, for example, and measure the distance between them to understand how far apart they are in time. If the signal you are measuring happens repeatedly — like a square or sine wave, for example — it hardly matters which set of peaks you look at. After all, they are all the same for practical purposes.

Pretty square waves all in a row. Channel 2 is 180 degrees out of phase (inverted). But is that all there is?

The problem occurs when you want to see something relative to a particular event. Basic scopes often have level triggering. They “start” when the input voltage goes above or below a certain value. Suppose you are looking at a square wave that goes from 0 V to 5 V. You could trigger at about 2.5 V, and the scope will never start in the middle of a cycle.

Digital scopes tend to capture data before and after the trigger, so the center of the screen will be right on an edge, and you’ll be able to see the square waves on either side. The picture shows two square waves on the screen with the trigger point marked with a T in the top center of the display. You can see the level in the top bar and also marked with a T on the right side of the screen.

What happens if there are no pulses on the trigger source channel? That depends. If you are in auto mode, the scope will eventually get impatient and trigger at random. This lets you see what’s going on, but there’s no reference. If you are in normal mode, though, the scope will either show nothing or show the last thing it displayed. Either way, the green text near the top left corner will read WAIT until the trigger event occurs. Then it will say T’D.

Continue reading “Beyond The Basics: Exploring Exotic Scope Trigger Modes” →

Parachute Drops Are Still A Viable Solution For Data Recovery From High Altitude Missions

December 19, 2023 by Lewin Day 12 Comments

Once upon a time, when the earliest spy satellites were developed, there wasn’t an easy way to send high-quality image data over the air. The satellites would capture images on film and dump out cartridges back to earth with parachutes that would be recovered by military planes.

It all sounds so archaic, so Rube Goldberg, so 1957. And yet, it’s still a viable method for recovering big globs of data from high altitude missions today. Really, you ask? Oh, yes indeed—why, NASA’s gotten back into the habit just recently!

Continue reading “Parachute Drops Are Still A Viable Solution For Data Recovery From High Altitude Missions” →

The IBM 5100, image from December 1975 issue of BYTE.

Bringing APL To The Masses: The History Of The IBM 5100

December 19, 2023 by Maya Posch 42 Comments

The 1970s was a somewhat awkward phase for the computer industry — as hulking, room-sized mainframes became ever smaller and the concept of home and portable computers more capable than a basic calculator began to gain traction. Amidst all of this, two interpreted programming languages saw themselves being used the most: BASIC and APL, with the latter being IBM’s programming language of choice for its mainframes. The advantages of being able to run APL on a single-user, portable system, eventually led to the IBM 5100. Its story is succinctly summarized by [Bradford Morgan White] in a recent article.

Although probably not well-known to the average computer use, APL (A Programming Language) is a multi-dimensional array-based language that uses a range of special graphic symbols that are often imprinted on the keyboard for ease of entry.

It excels at concisely describing complex functions, such as the example provided on the APL Wikipedia entry for picking 6 pseudo-random, non-repeating integers between 1 and 40 and sorting them in ascending order:

x[⍋x←6?40]

Part of what made it possible to bring the power of APL processing to a portable system like the IBM 5100 was the IBM PALM processor, which implemented an emulator in microcode to allow e.g. running System/360 APL code on a 5100, as well as BASIC.

Despite [Bradford]’s claim that the 5100 was not a commercial success, it’s important to remember the target market. With a price tag of tens of thousands of (inflation-adjusted 2023) dollars, it bridged the gap between a multi-user mainframe with APL and far less capable single-user systems that generally only managed BASIC. This is reflected in that the Commodore SuperPET supported APL, and the 5100 was followed by the 5110 and 5120 systems, and that today you can download GNU APL which implements the ISO/IEC 13751:2001 (APL2) standard.

We’ve previously looked at the Canadian-made MCM/70, another portable APL machine that embodied the cyberdeck aesthetic before William Gibson even gave it a name.

Top image: The IBM 5100, image from December 1975 issue of BYTE.

Thanks to [Stephen Walters] for the tip.

When Is An Engineer Not An Engineer? When He’s A Canadian Engineer

December 18, 2023 by Jenny List 218 Comments

In medieval Europe, many professions were under the control of guilds. These had a monopoly over that profession in their particular city or state, backed up with all the legal power of the monarch. If you weren’t in the guild you couldn’t practice your craft. Except in a few ossified forms they are a thing of the past, but we have to wonder whether that particular message ever reached Western Canada.

An electoral candidate with an engineering degree who practices what any sane person would call engineering, has been ordered by a judge to cease calling himself an engineer. The heinous crime committed by the candidate, one [David Hilderman], is to not be a member of the ~~guild~~ Association of Professional Engineers and Geoscientists of B.C. We get it that maybe calling a garbage truck driver a waste collection engineer may be stretching it a little, but here in the 21st century we think the Canadian professional body should be ashamed of themselves over this case. Way to encourage people into the engineering profession!

Here at Hackaday, quite a few of us writers are engineers. Stepping outside our normal third person, I, [Jenny List], am among them. My electronic engineering degree may be a little moth-eaten, but I have practiced my craft over several decades without ever being a member of the British IEE. No offence meant to the IEE, but there is very little indeed they have to offer me. If the same is true in Canada to the extent that they have to rely on legal sanctions to protect their membership lists, then we think perhaps the problem is with them rather than Canadian engineers. You have to ask, just how is an engineering graduate who’s not a guild member supposed to describe themselves? Some of us need to know, in case we ever find ourselves on holiday in Canada!

Header: Joe Gratz, CC0.

Renewable Energy: Beyond Electricity

December 18, 2023 by Bryan Cockfield 72 Comments

Perhaps the most-cited downside of renewable energy is that wind or sunlight might not always be available when the electrical grid demands it. As they say in the industry, it’s not “dispatchable”. A large enough grid can mitigate this somewhat by moving energy long distances or by using various existing storage methods like pumped storage, but for the time being some amount of dispatchable power generation like nuclear, fossil, or hydro power is often needed to backstop the fundamental nature of nature. As prices for wind and solar drop precipitously, though, the economics of finding other grid storage solutions get better. While the current focus is almost exclusively dedicated to batteries, another way of solving these problems may be using renewables to generate hydrogen both as a fuel and as a means of grid storage. Continue reading “Renewable Energy: Beyond Electricity” →

Mickey Shall Be Free!

December 18, 2023 by Jenny List 24 Comments

The end of the year brings with it festive cheer, and a look forward into the new year to come. For those with an interest in intellectual property and the public domain it brings another treat, because every January 1st a fresh crop of works enter the public domain.

We’ll take a look at the wider crop around the day, but this year the big story is that Mickey Mouse, whose first outing was in 1928’s Steamboat Willie, is to get his turn to be released from copyright. [Jennifer Jenkins] from Duke University’s Center for the Study of the Public Domain, is using Mickey’s impending release to take a look at the law surrounding such a well-protected work.

Mickey has perhaps the greatest symbolism of all intellectual property when it comes to copyright terms, having been the reason for the Disney Corporation’s successive successful attempts to have copyright terms extended. Now even their reach is about to come to an end, but beware if you’re about to use him in your work, for the Mickey entering the public domain is an early outing, without gloves or the colours and eyes of his later incarnations. Added to that, Disney have a range of trademarks surrounding him. The piece makes for an interesting read as it navigates this maze, and makes some worthwhile points about copyright and the public domain.

Last year, we welcomed Fritz Lang’s Metropolis to the public domain. Meanwhile if you’re reading this in 2023, we believe our use of a header image featuring the 1928 Mickey to be covered by the doctrine of fair use.

How Germany’s Troubled Pebble Bed Reactor Came Of Age In China

December 14, 2023 by Maya Posch 57 Comments

Although the concept of nuclear fission is a simple and straightforward one, the many choices for fuel types, fuel design, reactor configurations, coolant types, neutron moderator or reflector types, etc. make that nuclear fission reactors have blossomed into a wide range of reactor designs, each with their own advantages and disadvantages. The story of the pebble bed reactor (PBR) is among the most interesting here, with its development winding its way from the US Manhattan Project over the Atlantic to Germany’s nuclear power industry during the 1960s, before finding a welcoming home in China’s rapidly growing nuclear power industry.

As a reactor design, PBRs do not use fuel rods like most other nuclear reactors, but rather spherical fuel elements (‘pebbles’) that are inserted at the top of the reactor vessel and extracted at the bottom, allowing for continuous refueling, while helium acts as coolant. With a strong negative temperature coefficient, the design should be extremely safe, while providing high-temperature steam that can be used for applications that otherwise require a coal boiler or gas turbine.

With China recently having put its twin-PBR HTR-PM plant into commercial operation, why is it that it was not the US, Germany or South Africa to first commercialize PBRs, but relative newcomer China?

Continue reading “How Germany’s Troubled Pebble Bed Reactor Came Of Age In China” →