The “Three Fives” Discrete 555 Timer Kit

555 kit

We’re pleased to announce our newest kit, the “Three Fives” Kit, a kit to build your own 555 timer circuit out of discrete components. Here’s a way to re-create one of the most classic, popular, and all-around useful chips of all time.

The kit is a faithful and functional transistor-scale replica of the classic NE555 timer integrated circuit, one of the most classic, popular, and all-around useful chips of all time. The kit was designed and developed as a collaboration with Eric Schlaepfer, based on a previous version (pictured here), and adapted from the equivalent schematic in the original datasheets for the device.  There have been a few other examples of circuits like these (such as the one that we featured in our article about the 555 contest), but we really like how this one has come together.

555 kit

The kit is designed to resemble an (overgrown) integrated circuit, based around an extra-thick matte-finish printed circuit board. The stand— which gives the circuit board eight legs in the shape of DIP-packaged integrated circuit pins —is made from machined and formed semi-rigid PVC foam.

555 kit

To actually hook up to the giant 555, there are the usual solder connection points, but there are also thumbscrew terminal posts that you can use with bare wires, solder lugs, or alligator clips.

555 kit

One of the really cool things about having a unintegrated disintegrated discrete circuit like this is that you can actually hook up probes and monitor what happens at different places inside the circuit.

555 kit

So that’s our new “Three Fives” Kit (shown above with an original NE555 for scale). It’s not quite as big as our 555 footstool, nor as tasty as our edible version, but it’s a great little circuit, and it’s got legs.

Photomask Mirrors

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At our local Silicon Valley electronics surplus shops and electronics flea market, we frequently come across all sorts of bizarro semiconductor manufacturing paraphernalia. Here is one of those types that we have written about before, in our coaster project:

Photolithographic masks, or photomasks are clear templates used in semiconductor manufacturing. Typically, they are made of UV-grade fused silica and have a highly intricate chrome metal film pattern on one side.

The most commonly available masks are test patterns used for calibration, as production masks are guarded carefully. This particular one dates back to 1983!

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Now looking inside at it, it’s hardly a mask at all. It’s nearly fully silvered—perhaps a mask pulled out before the etching step of its process.

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If you look at an oblique angle, you will find a few incredibly detailed patterns, and some printed on markings. This one is marked “5.1 INCH ARRAY” across the top and “1447 3-OCT-83-13. 5” across the bottom.

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So, what to do with them? Since they don’t have the neat patterns that made those coasters so cool, we used some truss-head screws to mount them to the wall.

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And here we are then, using a couple of photolithographic mask as bathroom mirrors! (With a couple of units at different heights for different-height people.) It solves a couple of problems at once: how to display the beautiful ephemera of semiconductor manufacturing, and what to do about a soulless little extra bathroom at our shop that didn’t come with a mirror.

 

Dr. Nim

Our friend Brian (the designer of the EBB driver board which is used in the Eggbot) recently posted this picture on twitter, with the following caption:

Kids found 1966 ‘computer’ ‘game’ in the closet and LOVE it. Dr. Nim always wins. Our future may be OK.

Dr. NIM was designed by the same engineer, John Godfrey, who designed the Digi-Comp II, and it was manufactured in the mid-1960′s by the same company, E.S.R. Inc. It is even described in the same patent as the Digi-Comp II and works in the same manner, using mechanical flip-flops triggered by marbles. Only, to play the ancient game of Nim instead of doing binary calculations. We were very curious about how Brian came by one, and asked for more information. He wrote what follows:

We were on a week long vacation in Michigan. We rented a large house on the shore of Lake Michigan near Traverse City. The house looked like an extreme example of 1960′s decorating—nothing has been updated since. (Large tables with built-in ash trays, shag carpet, an old radio that had a “magic eye” that lit up when your FM radio station was ‘in hi-fi stereo’, etc.) And, in the closet with the games, was one called Dr. Nim. Us adults never gave it a second glance until one of the older kids noticed that it said “computer” on it, and pulled it out to see if she could get on Facebook with it. My ears perked up, and when I saw the front cover, I couldn’t stop playing with it. Which is not surprising considering my background as an embedded systems engineer. But what I couldn’t believe is that the kids loved it too! We were on vacation with 2 other families, each of which had 3 kids (like ours) of various ages. Very quickly, the 10 year old figured out how to beat Dr. Nim. Of course that made all the other kids want to try. Even the 4 year old learned to play. And then some of the other adults (even non-engineers) tried it for themselves, asking how it could possibly know how many marbles to take each turn so that it would (almost) always win. “How can pieces of plastic be a computer?” they asked. So we had a nice chat about where the term ‘computer’ comes from.

The thing that got me most excited was not that (modern) kids picked it up and were fascinated by it, nor that other adults were intrigued, but the thought that, in 1968 when it was available for sale to the general public, enough normal Americans bought it that it ended up in people’s game closets along with decks of cards and Monopoly. I suppose the thought of owning a ‘computer’ when such things were all the rage, was so new that spending a few dollars on a plastic mechanical game computer was something a lot of people did just out of curiosity.

And the instruction manual! I should have scanned it in. It has a mini-course in binary logic and boolean equations, ending with a discussion on how the game works, and how you can set it up in several different ways to play different games. And then it went on with “does this mean Dr. Nim can think?” and the open ended questions of machine thinking.

Too bad somebody doesn’t make something like that today . . . .  <grin>

After Brian wrote back to us, we found the manual for Dr. Nim through the Friends of Digi-Comp group. (Dr. Nim games frequently come up on eBay as well, if you’re interested in playing with one.)

The manual is truly incredible, with in-depth discussions about not just the mechanism of the game, but commentary on the effect of computing on culture in the long run. We’ll leave you with a thought from the manual, c. 1965:

The strides that man has made in the last 15 years in developing machines that extend and supplement his thinking are truly astounding. Who can say what enormous strides will take place in the next 15 to 30 years?

How Printed Circuit Boards are Designed (1960 Edition)

We found this gem in A Manual of Engineering Drawing for Students and Draftsmen, 9th Ed., by French & Vierck,1960, p. 487.

Printed Circuits allow miniaturization and the elimination of circuit errors—advantages that cannot be obtained by other methods. Once a pattern or suitable design is established, preparation of a black and white drawing can start. Scales for reduction, for example, 4 to 1, 3 to 1, or 2 to 1, are used. To insure sufficient bonding area of the metal laminate during soldering operations, lines should not be less than 1/32 inch in width when reduced. Line separation should never be closer than 1/32 inch on the final circuit. Figure 19.24 illustrates the drawing of printed circuits.

From the Mailbag: On the Digi-Comp II

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Peter wrote in about his experience with the Digi-Comp II:

I just wanted you and the entire Evil Mad Scientist team to know that the Digi-Comp II was a big success.  I used it to explain digital computers to a group of second graders and fifth graders. In an age of iPads and smartphones, it’s surprisingly hard to demonstrate the beauty and magic of digital computer.  The Digi-Comp II was perfect, looked great, and worked flawlessly. Thanks!

Introduction to Analog Mechanical Computers

Courtesy of the United States Navy comes this incredible introduction to analog mechanical computers.

The context for this is that massive, mechanical computers were used aboard US Navy ships ranging from destroyers to battleships, from about 1944-1969, as part of the “Fire Control” system.  This type of computer would take up to 25 continuously changing input variables in order to calculate the proper bearing and elevation for heavy caliber guns aboard the ship.  This calculation— to ensure that a projectile will land at the place where the target is going to be —is marvelously complex, taking into account variables such as wind speed and direction, relative velocity of the ship and target, and parallax between the different guns on the ship.  What’s truly remarkable is that it was all done with mechanical  mechanisms such as gear differentials, cams, and mechanical integrators.

This two-part training film, from 1953, introduces the basic mechanisms that made these computers work:

The video embedded above (41:53 total length) contains both films, one after the other.  (And, the YouTube link is here.)

Basic Mechanisms in Fire Control Computers, Part 1 discusses shafts, gears, cams, and differentials. Note that the first couple of minutes are not so much about the mechanisms, but more of an explanation— to the servicemen —of why they needed to learn about them.

Basic Mechanisms in Fire Control Computers, Part 2 discusses component solvers, integrators, and multipliers

 

If you enjoy these training films, you may also want to read through the little book entitled Ordnance Pamphlet 1140: Basic Fire Control Mechanisms, available here in PDF format, which covers much of the same ground.