Hackaday Podcast 052: Shorting Components, Printing Typewriter Balls, Taking Minimal Time Lapse, And Building A Makerspace Movie Prop

Hackaday editors Elliot Williams and Mike Szczys recap a great week in hardware hacking. There’s perfection in the air as clever 3D-printing turns a button and LED matrix into an aesthetically awesome home automation display. Take a crash course in RF modulation types to use on your next project. Did you know the DB-9 connector is actually a DE-9? Building your own underwater ROV tether isn’t as simple as it sounds. And Elliot found a treasure trove of zero-ohm jumpers in chip packages — what the heck are these things for?

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

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Can You Help 3D Print A Selectric Ball?

The IBM Selectric changed typewriters as we knew them. Their distinctive ball element replaced the clunky row of typebars and made most people faster typists. When [Steve Malikoff] thought about 3D printing a type ball — colloquially known as a golf ball — it seemed like a great idea.

The problem? It just doesn’t work very well. According to [Steve], it is likely because of the low resolution of the printer. However, it isn’t clear the latitudes of the characters are correct. and there are a few other issues. It is possible that a resin printer would do better and there’s a call for someone out there to try it and report back. We are guessing a finer nozzle and very low layer height might help on an FDM printer.

Judging from the images, it looks like some of the balls do pretty well, but don’t get a full strike at the tilt angle. So it could be something else. However, it does sound like cleaning up the print so it fits is a major problem.

The Selectric was notable for several reasons — you can see an ad for the machine in the video below. The type ball meant you couldn’t jam keys. Since you didn’t have to unjam keys and you had the ribbon in a cartridge, you would have to work really hard to get ink on your fingers, even if you used the cloth ribbon instead of the arguably better carbon film ribbon. The Selectric II could even use a special tape to lift the carbon ribbon off the paper for correcting mistakes. No white-out liquid or fussing with little strips of correction paper. The fact that the ball moves means you don’t have to clear space on the side of the machine for the platen to travel back and forth.

Can you help? If you have a Selectric I or II and a high-quality printer, this would be a fun project to try and report back your results to [Steve]. If you are familiar with the later issue typeballs, you might not have seen the wire clip that [Steve] uses to hold the ball in place. However, you can see them in the video ad below. More modern balls use a plastic lever that acts as a handle so even with cloth ribbons you have less chance of getting ink on your hands.

Although there were Selectrics meant to interface with a computer, you can refit any of them to do it with some work. The Selectric also has a role in one of the great techno spy stories of all time: The GUNMAN project.

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Retrotechtacular: Cold War-Era Hardware Keyloggers

As Cold War tensions increased throughout the 1970s, the Soviets pulled out all the stops when it came to digging up information from US diplomats. This NSA memo from 2012 explains how several IBM Selectric typewriters used in the Moscow and Leningrad offices were successfully bugged with electromechanical devices that could possibly have been the world’s first keyloggers.

The Selectric prints with a ball that is spun and tilted to select the desired character. Two mechanical arms control the ball’s spin and tilt, and the keylogger read out the position of those arms. Thus, each character on the Selectric’s type element ball has its own signature. The sensing part of the keylogging mechanism was buried in part of the typewriter chassis, a metal bar that spans the width of the machine, and were so well hidden that they could only have been detected by complete dissassembly or x-ray.

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Turning An IBM Selectric Into A Printer.

In the days when computers took up an entire room, a CRT monitor was a luxury. Most of the time, input and output was handled with a teletype – a typewriter connected directly to the computer. [Josh] wanted his own typewriter terminal, so he took apart an IBM Selectric II and got to work.

Instead of an electronic keyboard, the IBM Selectric II uses and electromechanical keyboard to tilt and rotate the Selectric’s typeball. In normal operation, a series of shafts underneath the keyboard are engaged. [Josh] added parts of an erector set to those levers and tied each one to one of 16 solenoids.

With a set of solenoids able to print any key with the help of an Arduino, [Josh] had a fully automated typewriter from the early 1970s. [Josh has been printing out a lot of ASCII art lately in preparation for the Kansas City Maker Faire later this month. You can check out the build videos after the break.

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