Milspec Teardown: CP-142 Range Computer

February 19, 2018 by Tom Nardi 69 Comments

As some of my previous work here at Hackaday will attest to, I’m a big fan of World War II technology. Something about going in with wooden airplanes and leaving with jet fighters and space capable rockets has always captivated me. So when one of my lovingly crafted eBay alerts was triggered by something claiming to be a “Navy WWII Range Computer”, it’s safe to say I was interested.

Not to say I had any idea of what the thing was, mind you. I only knew it looked old and I had to have it. While I eagerly awaited the device to arrive at my doorstep, I tried to do some research on it and came up pretty much empty-handed. As you might imagine, a lot of the technical information for hardware that was developed in the 1940’s hasn’t quite made it to the Internet. Somebody was selling a technical manual that potentially would have covered the function of this device for $100 on another site, but I thought that might be a bit excessive. Besides, where’s the fun in that?

I decided to try to decipher what this device does by a careful examination of the hardware, consultation of what little technical data I could pull up on its individual components, and some modern gear. In the end I think I have a good idea of how it works, but I’d certainly love to hear if there’s anyone out there who might have actually worked with hardware like this and could fill in any blanks.

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Help Keep The Bombe At Bletchley

February 17, 2018 by Jenny List 36 Comments

Fans of vintage codebreaking machinery might be interested to hear that the only working reconstruction of a Turing-Welchman Bombe is likely to soon be on the move. The electromechanical device, a replica of those used on the Second World War Enigma codes, is housed at Bletchley Park, the former codebreaking center established before the outbreak of war to house British and Polish codebreakers.

Bletchley Park itself is now a tourist attraction. The news is that a display reorganization has caused the Turing Welchman Bombe Rebuild Trust that owns the Bombe to approach the neighboring National Museum Of Computing with a view to housing it alongside their reconstruction of the Colossus electronic computer. The Colossus was famously used on the Lorenz cipher. This is an exciting development for the museum, but as an organization reliant on donations they face the task of finding the resources to create a new gallery for the arrival. To that end, they have launched a crowdfunding campaign with a target of £50000 ($69358.50), and they need your donations to it for the project to succeed. They have raised over £4500 in the few days it has already been open and there is most of a month still to go, so we hope they achieve their goal.

The Bletchley Park site is now surrounded by the post-war new town of Milton Keynes, and is easy enough to get to should you find yourself in the UK. We visited The National Museum Of Computing a couple of years ago and spent a very happy day touring its extensive and fascinating collection. If you want to read more about the Bombe you might like to read our review, and also our impression of Colossus.

As part of their campaign, the museum has produced a promotional video, which we have placed after the break.

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This Boxing Bell Is A Trip

February 17, 2018 by Adam Fabio 8 Comments

[MeasuredWorkshop] wanted to know how a boxing bell mechanism worked. The best way to learn is by doing, so he jumped right in and built one! Boxing bells are a rare surviving example of the trip bell mechanism. Trip bells were used in schools and public buildings as fire alarms. They’ve since been replaced by modern electric systems.

The mechanical linkage behind the trip bell is a one-way lever. This is the arm you pull on. It has a hinged section which stays rigid when the arm is pulled down, but rotates away when the arm is released. [Measured Workshop] built the mechanics of his bell using rather basic tools. The brunt of the work was handled by an angle grinder and a drill press.

The sounder for this boxing bell came from an old school bell. The industrial grey paint was chemically stripped, and the metal cleaned up for a nice brushed finish. The metal stands out nicely against the wood board [Measured Workshop] used as a base.

The finished product looks and sounds the part – now he just has to find a boxing gym in need of a bell!

We’re really becoming fond of the “wordless workshop” style videos that have been popping up on YouTube. [Jimmy DiResta] has been doing it for years, and relative newcomers [HandToolRescue] and [Measured Workshop] are both producing some great content!

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Resurrecting An Amiga CD32

February 16, 2018 by Richard Baguley 15 Comments

As an editor on Amiga magazines in a previous life, this is kind of bittersweet. [RetroManCave] was donated an Amiga CD32 games system, and it is trying to resurrect it. If you’ve not heard of it, the CD32 was a 1993 games console based on the Amiga home computer system. It was the last gasp for Commodore, the beleaguered company behind the Amiga. In this first video of a series, they take the system apart, take you through what’s inside and boot it up. The system boots, but there is some sort of problem with the video sync, and they will be taking a closer look at fixing that next. We have featured a couple of similar projects from [RetroManCave] before, such as their brain transplant on a Big Trak toy and Commodore 64 fix. This video (after the break) is worth a watch if you are curious about old systems like this, want some tips on resurrecting old hardware or just want to shed a tear as your misspent youth is torn apart before your eyes.

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How To Control The Lights With A TV Remote

February 16, 2018 by Lewin Day 16 Comments

In this day and age of the Internet of Things and controlling appliances over the internet, the idea of using an old-fashioned television remote to do anything feels distinctly 2005. That doesn’t mean it’s not a valid way to control the lights at home, and [Atakan] is here to show us how it’s done.

To the experienced electronics maker, this is yesterday’s jam, but [Atakan] goes to great lengths to hash out the whole process from start to finish, from building the circuitry to switch the lights through to the code necessary to make a PIC do your bidding. It’s rare to see such a project done with a non-Arduino platform, but rest assured, such things do exist. There’s even some SPICE simulation thrown in for good measure, if you really want to get down to the nitty-gritty.

Perhaps the only thing missing from the writeup is a primer on how to execute the project safely, given that it’s used with a direct connection to live mains wiring. We’d love to hear in the comments about any changes or modifications that would be necessary to ensure this project doesn’t hurt anyone or burn an apartment complex down. Sometimes you can switch lights without a direct connection to the mains, however – like this project that interfaces mechanically with a standard light switch.

The UA723 As A Switch Mode Regulator

February 15, 2018 by Jenny List 37 Comments

If you are an electronic engineer or received an education in electronics that went beyond the very basics, there is a good chance that you will be familiar with the Fairchild μA723. This chip designed by the legendary Bob Widlar and released in 1967 is a kit-of-parts for building all sorts of voltage regulators. Aside from being a very useful device, it may owe some of its long life to appearing as a teaching example in Paul Horowitz and Winfield Hill’s seminal text, The Art Of Electronics. It’s a favourite chip of mine, and I have written about it extensively both on these pages and elsewhere.

The Fairchild switching regulator circuit. From the μA723 data sheet in their 1973 linear IC databook, page 194 onwards.

For all my experimenting with a μA723 over the decades there is one intriguing circuit on its data sheet that I have never had the opportunity to build. Figure 9 on the original Fairchild data sheet is a switching regulator, a buck converter using a pair of PNP transistors along with the diode and inductor you would expect. Its performance will almost certainly be eclipsed by a multitude of more recent dedicated converter chips, but it remains the one μA723 circuit I have never built. Clearly something must be done to rectify this situation.

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This IS Your Grandfather’s Radio

February 14, 2018 by Al Williams 9 Comments

Tube radios have a certain charm. Waiting for them to warm up, that glow of the filaments in a dark room. Tubes ruled radio for many decades. [Uniservo] posted a video about the history and technology behind the 1920’s era Clapp-Eastham C-3 radio. This is a three-tube regenerative receiver and was advanced for its day.

If you are worried he won’t open it up, don’t despair. Around the ten minute mark, your patience will be rewarded. Inside are three big tubes full of getter and bus bars instead of wires. Add to that the furniture-quality case, and this is a grand old radio.

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