Resurrection — Pressing WW2 Radio Equipment Back Into Service

November 9, 2016 by Gregory L. Charvat 37 Comments

Mass production was key to survival during the Second World War. So much stuff was made that there continues to be volumes of new unpacked stuff left over and tons of used equipment for sale at reasonable prices. Availability of this war surplus provided experimenters in the mid 20th century with access to high performance test equipment, radio equipment, and high quality components for the first time.

Even today this old stuff continues to motivate and inspire the young generations because of its high build quality, unique electro-mechanical approaches, and overall innovative designs which continue to be relevant into the 21st century. In this post we will show you how to get started in the hobby of resurrecting WW2 radio equipment and putting it back on the air.

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Perceptrons In C++

November 8, 2016 by Al Williams 19 Comments

Last time, I talked about a simple kind of neural net called a perceptron that you can cause to learn simple functions. For the purposes of experimenting, I coded a simple example using Excel. That’s handy for changing things on the fly, but not so handy for putting the code in a microcontroller. This time, I’ll show you how the code looks in C++ and also tell you more about what you can do when faced with a more complex problem.

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Crossing Wheatstone Bridges

November 8, 2016 by Steven Dufresne 18 Comments

The Wheatstone bridge is a way of measuring resistance with great accuracy and despite having been invented over 150 years ago, it still finds plenty of use today. Even searching for it on Hackaday brings up its use in a number of hacks. It’s a fundamental experimental device, and you should know about it.

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Fictional Hacking: Michael Westen

November 7, 2016 by Al Williams 55 Comments

I don’t know if it is true or not today, but in fiction, spies depend on lots of high-tech gadgets. I do know that during World War II, the various secret services like the OSS and the SOE did have gadgets like secret transmitters and concealed weapons. But, like [James Bond’s] grenade-launching ink pen, to [Maxwell Smart’s] shoe phone, those gadgets came from some organized lab. (When you watch the video below, remember that at that time, a personal phone going off in a theater was unknown as cell phones were years in the future.)

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A Realistic Look At The Death Of A Standard

November 7, 2016 by Gerrit Coetzee 239 Comments

A bit ago I wrote an article called, “Death To The 3.5mm Audio Jack, Long Live Wireless.” A few readers were with me, a few were indifferent, many were vehemently against me, and there was a, not insubstantial, subset in a pure panic about the potential retirement of a beloved connector. Now I used a lot of opinionated language dispersed with subjectively evaluated facts to make a case that the connector is out. Not today maybe, but there is certainly a tomorrow not so far off where there are more wireless headsets at the electronics store than wired ones.

I think I saw a laserdisc player in operation exactly once. — I think I saw a Laserdisc player in operation exactly once.

So what happens when a standard dies? What happens when technology starts to move on? Let’s take a look at the CD-ROM. Continue reading “A Realistic Look At The Death Of A Standard” →

Retrotechtacular: FAX As A Service In 1984

November 4, 2016 by Al Williams 29 Comments

If you tell someone these days to send you something via FAX, you are likely to get a look similar to the one you’d get if you asked them to park your horse. But in 1984, FAX was a mysterious new technology (well, actually, it wasn’t, but it wasn’t yet common to most people).

FedEx–the people who got famous delivering packages overnight–made a bold move to seize a new market: Zapmail (not to be confused with the modern mass mailing service). The idea was simple (you can see a commercial for it in grainy VHS splendor below): Overnight is great, but sometimes you need something sent across the country now. A FedEx driver picks up your documents, carries them to a FedEx office. There the documents FAX to another FedEx office where another driver delivers the printed copy. The process took two hours to get a paper document from one side of the continent to another.

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Tools Of The Trade — Injection Molding

November 4, 2016 by Bob Baddeley 34 Comments

Having finished the Tools of the Trade series on circuit board assembly, let’s look at some of the common methods for doing enclosures. First, and possibly the most common, is injection molding. This is the process of taking hot plastic, squirting it through a small hole and into a cavity, letting it cool, and then removing the hardened plastic formed in the shape of the cavity.

The machine itself has three major parts; the hopper, the screw, and the mold. The hopper is where the plastic pellets are dumped in. These pellets are tiny flecks of plastic, and if the product is to be colored there will be colorant pellets added at some ratio. The hopper will also usually have a dehumidifier attached to it to remove as much water from the pellets as possible. Water screws up the process because it vaporizes and creates little air bubbles.

Next the plastic flecks go into one end of the screw. The screw’s job is to turn slowly, forcing the plastic into ever smaller channels as it goes through a heating element, mixing the melted plastic with the colorant and getting consistent coloring, temperature, and ever increasing pressure. By the time the plastic is coming out the other end of the screw, and with the assistance of a hydraulic jack, it can be at hundreds of tons of pressure.

Finally, the plastic enters the mold, where it flows through channels into the empty cavity, and allowed to sit briefly to cool. The mold then separates and ejector pins push the part out of the cavity.

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