Project Starline Realizes Asimov’s 3D Vision

May 20, 2021 by Al Williams 36 Comments

Issac Asimov wrote Caves of Steel in 1953. In it, he mentions something called trimensional personification. In an age before WebEx and Zoom, imagining that people would have remote meetings replete with 3D holograms was pretty far-sighted. We don’t know if any Google engineers read the book, but they are trying to create a very similar experience with project Starline.

The system is one of those that seems simple on the face of it, but we are sure the implementation isn’t easy. You sit facing something that looks like a window. The other person shows up in 3D as though they were on the other side of the window. Think prison visitation without the phone handset. The camera is mounted such that you look naturally at the other person through your virtual window.

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Practical Sensors: The Hall Effect

May 20, 2021 by Al Williams 22 Comments

Measuring a magnetic field can be very easy with some pretty low tech, or it can be very high tech. It just depends on what kind of measurement you need and how much effort you want to expend. The very simplest magnetic sensors are reed switches. These are basically relays with no coil. Instead of a coil, an external magnet gets close enough to make or break the contacts in the reed. You see these a lot in, for example, door alarm sensors.

Then again, there’s no real finesse to a reed. It changes state when it sees enough of a magnetic field and that’s about all. You could use a compass with some sort of detection on the needle to get some more information about the field, but not much more. That was, however, how early magnetometers worked. Today, you have lots of options, including the nearly ubiquitous Hall effect sensor.

You might use a Hall effect to measure the magnetic button on a keyboard key coming down when you press it or the open and closed state of a valve. A lot of Hall effects see service as current monitors. Since a coil generates a magnetic field proportional to the current through it, a magnetic sensor can estimate the current in a coil of wire without any physical contact. Hall effects can also watch a magnet go by in a linear motion system or a rotating system to get an idea of position or speed. For example, check out this brushless motor controller that uses three sensors to understand the motor’s position.

History

Edwin Hall identified the effect in 1879. The basic idea is simple: an electrical conductor carrying current will exhibit changes due to an external magnetic field nearby. These changes show up as voltage you measure across the conductor. Normally, the voltage across a conductor will be nearly zero, but with a magnetic field, you’ll get a non-zero reading in proportion to the magnetic field strength in a particular plane, as we’ll see shortly.

Hall effect sensors are just one type of modern magnetometer. There are many different kinds including those that use inductive pickup coils that may or may not rotate or a fluxgate, which is a special type of coil. Some use a scale or a spring to measure force against another magnet — sometimes microscopically. You can even detect a magnetic field using optical properties like the Kerr effect or Faraday rotation.

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Inside The VIC-20

May 19, 2021 by Al Williams 52 Comments

Commodore machines are well-loved around here, but usually when you think Commodore, you think about the Commodore 64, or maybe the PET or Amiga. But the Commodore 64 had an older sister, the VIC 20. This was the first computer to sell a million units and has a lot in common with its better-known successor. The machine was only made for a few years, and [Dubious Engineering] has been restoring one over a few videos. In the video below, he opens it up for a look inside, among other things.

If you want to get straight to the opening, you’ll need to fast forward about 5 and a half minutes. The keyboard pulls off and a nice old-fashioned set of cables made from individual wires connect to the skinny main board with all the smarts on it. No ribbon cables or flex PCBs!

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FIR Filters For Xilinx

May 18, 2021 by Al Williams 7 Comments

Digital filters are always an interesting topic, and they are especially attractive with FPGAs. [Pabolo] has been working with them in a series of blog posts. The latest covers an 8th order FIR filter in Verilog. He covers some math, which you can find in many places, but he also shows how an implementation maps to DSP slices in a device. Then to reduce the number of slices, he illustrates folding which trades delay time for slice usage.

Folding takes a multi-stage parallel multiplication and breaks it into fewer multiplications done over a longer period of time. This reuses slices to reduce the number required for high-order filters.

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Do You Really Own It? Motorcycle Airbag Requires Additional Purchase To Inflate

May 18, 2021 by Al Williams 218 Comments

If you ride a motorcycle, you may have noticed that the cost of airbag vests has dropped. In one case, something very different is going on here. As reported by Motherboard, you can pick up a KLIM Ai-1 for $400 but the airbag built into it will not function until unlocked with an additional purchase, and a big one at that. So do you really own the vest for $400?

Given the nature of the electronics and computer business lately, we spend a good bit of time thinking of what it means to own a piece of technology. Do you own your cable modem or cell phone if you aren’t allowed to open it up? Do you own a piece of software that wants to call home periodically and won’t let you stop it? Sometimes it makes sense that you are paying for a service. But there have been times where, for example, a speaker company essentially bricks devices that could work fine on their own even though you — in theory — own the device.

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Spy Tech: CIA Masks In Five Minutes Or Less

May 18, 2021 by Al Williams 23 Comments

You know the old trope: James Bond is killed but it turns out to be someone else in an incredibly good-looking Sean Connery mask. Mission: Impossible and Scooby Doo regularly had some variation of the theme. But, apparently, truth is stranger than fiction. The CIA has — or at least had — a chief of disguise. A former holder of that office now works for the International Spy Museum and has some very interesting stories about the real masks CIA operatives would use in the field.

According to the video you can see below, the agency enlisted the help of Hollywood — particularly the mask maker from Planet of the Apes — to help them with this project. Of course, in the movies, you can take hours to apply a mask and control how it is lit, how closely the camera examines it, and if something goes wrong you just redo the scene. If you are buying secret plans and your nose falls off, it would probably be hard to explain.

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A “Disgusting” 1980s Computer Restored

May 17, 2021 by Al Williams 42 Comments

It takes a special eye to see a junkyard car and envision it as your latest hotrod. The guys at RMC found what they termed a “disgusting” Acorn Electron and decided to restore it to its former glory. The Electron was a budget version of the BBC micro with a 6502 running at 2 MHz when executing code from ROM and 1 MHz when it hit the RAM. Apparently, at least some of the bus was operating at 4 bits instead of 8. Go figure.

The 1982 machine was meant to head off the Sinclair ZX and was set to sell for about £200. However, the machine didn’t catch on like the Sinclair and undersold it by around 20 times with a paltry quarter of a million units.

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