Author: Al Williams

3965 Articles

Intuition About Maxwell’s Equations

November 13, 2024 by 13 Comments

You don’t have to know how a car engine works to drive a car — but you can bet all the drivers in the Indy 500 have a better than average understanding of what’s going on under the hood. All of our understanding of electronics hinges on Maxwell’s equations, but not many people know them. Even fewer have an intuitive feel for the equations, and [Ali] wants to help you with that. Of course, Maxwell’s gets into some hairy math, but [Ali] covers each law in a very pragmatic way, as you can see in the video below.

While the video explains the math simply, you’ll get more out of it if you understand vectors and derivatives. But even if you don’t, the explanations provide a lot of practical understanding

Understanding the divergence and curl operators is one key to Maxwell’s equations. While this video does give a quick explanation, [3Blue1Brown] has a very detailed video on just that topic. It also touches on Maxwell’s equations if you want some reinforcement and pretty graphics.

Maxwell’s equations can be very artistic. This is one of those topics where math, science, art, and history all blend together.

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Teaching Computers To Read — Sort Of

November 12, 2024 by 8 Comments

If you ask someone who grew up in the late 1970s or early 1980s what taught them a lot about programming, they’d probably tell you that typing in programs from magazines was very instructive. However, it was also very boring and error-prone. In fact, we’d say it was less instructional to do the typing than it was to do the debugging required to find all your mistakes. Magazines hated that and, as [Tech Tangents] shows us in a recent video, there were efforts to make devices that could scan barcodes from magazines or books to save readers from typing in the latest Star Trek game or Tiny Basic compiler.

The Cauzin Softstrip was a simple scanner that could read barcodes from a magazine or your printer if you wanted to do backups. As [Tech Tangents] points out, you may not have heard of it, but at the time, it seemed to be the future of software distribution.

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Retrotechtacular: Color TV

November 12, 2024 by 20 Comments

We have often wondered if people dreamed in black and white before the advent of photography. While color pictures eventually became the norm, black and white TV was common for many years. After all, a TV set was a big investment, so people didn’t run out and buy the latest TV every year. Even if you did buy a new or used TV, a black and white model was much less expensive and, for many years, some shows were in black and white anyway. RCA, of course, wanted you to buy a color set. [PeriscopeFilm] has a 1963 promotional film from RCA extolling the virtues of a color set. The video also shows something about how the sets were made, as you can see below.

We aren’t sure we’d have led with the idea that color could save your life in this context, but we have to salute the melodrama. There is a good bit of footage of picture tube manufacturing, although the technical detail is — understandably — aimed at the general public.

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Z80 Testing The 80s Way

November 12, 2024 by 23 Comments

According to [MTSI], if you used a Z80 chip back in the 1980s, it almost certainly passed through the sole Fairchild Sentry 610 system that gave it the seal of approval.

The Sentry was big iron for its day. The CPU was a 24-bit device and ran at a blistering 250 kHz. Along with a tape drive and a specialized test bed, it could test Z80s, F8s, and other Mostek products of the day. There was a disk drive, too. The 26-inch platters stored under 10 kilobytes. Despite the relatively low speed of the CPU, the Sentry could test devices running up to 10 MHz, which was plenty for the CPUs it was testing. The actual test interface ran at 11 MHz and used an exotic divider to generate slower frequencies.

According to the post, an informal count of the number of chips in the device came up with around 60,000. That, as you might expect, took a huge power supply, too.

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Retrogadgets: Oscilloscope Cameras

November 11, 2024 by 23 Comments

Today, if you want to get a picture from your oscilloscope — maybe to send to a collaborator or to stick in a document or blog post — it is super easy. You can push an image to a USB stick or sometimes even just use the scope’s PC or web interface to save the picture directly to your computer. Of course, if it is on the computer, you could use normal screen capture software. But that hasn’t always been the case. Back in the days when scopes were heavy and expensive, if you wanted to capture an image from the tube, you took a picture. While you might be able to hold up your camera to the screen, they made specific cameras just for this purpose.

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Cheap Sensor Changes Personality

November 10, 2024 by 27 Comments

If you want to add humidity and temperature sensors to your home automation sensor, you can — like [Maker’s Fun Duck] did — buy some generic ones for about a buck. For a dollar, you get a little square LCD with sensors and a button. You even get the battery. Can you reprogram the firmware to bend it to your will? As [Duck] shows in the video below, you can.

The device advertises some custom BLE services, but [Duck] didn’t want to use the vendor’s phone app, so he cracked the case open. Inside was a microcontroller with Bluetooth, an LCD driver, a sensor IC, and very little else.

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Component Tester Teardown

November 10, 2024 by 9 Comments

In the modern age, when you hear “component tester” you probably think of one of those cheap microcontroller-based devices that can identify components and provide basic measurements on an LCD screen. However, in the past, these were usually simple circuits that generated an XY scope plot. The trace would allow an experienced operator to identify components and read a few key parameters. [Thomas] tears down an old Hameg device that uses this principle in the video below.

The unit is in a nice enclosure and has a feature that controls the amount of current the unit uses in the excitation signal. It plugs into the wall, and you can connect the component under test with either test leads or a socket. The output, of course, is a pair of BNCs for the scope’s X and Y inputs.

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