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Build Your Own Giant 555 Timer Chip

Make a drop-in replacement kit for the 555 integrated circuit with discrete transistors and resistors

4 min read
Build Your Own Giant 555 Timer Chip
Photo: Evil Mad Scientist Laboratories

Biologists have plastic DNA helices, astronomers have celestial globes, and chemists the ubiquitous periodic table wall chart. These iconic objects each encapsulate a foundational piece of working knowledge, recognizable to all practitioners in a field. Sadly, such touchstones are thin on the ground for electrical engineers. Although pretty, vacuum tubes, for example, are a niche technology these days, while the transistors and integrated circuits that define the discipline are a bit on the small side for easy viewing. So I was pleased when I learned about the recent creation of the US $35 Three Fives Discrete 555 Timer Kit, sold by Evil Mad Scientist, a DIY and open-source hardware company located in Silicon Valley.

The Three Fives kit is a working model of the 555 integrated circuit. It’s hard to think of an IC more ubiquitous than the 555 timer, which was introduced in 1971. There can’t be an electrical engineer alive today who hasn’t used a 555 at some point, for tasks ranging from simply making a light blink on and off to pulse-width modulation; in January’s Hands On article, our contributor used the 555 to make a music organ with conductive ink traces. Unlike many other chips that have come and gone over the decades, the 555 is still finding its way into all kinds of prototypes and products, with no end in sight (for the origins of the chip, see “25 Microchips That Shook the World,” IEEE Spectrum, May 2009). Just as DNA models, star maps, and periodic tables serve as reminders of fundamentals that can get obscured by day-to-day minutiae, so too the Three Fives kit is a reminder that even the most complex digital processor is still at its heart just a collection of very simple components.

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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