The Power of the Digi-Comp II

Last fall, we built an oversized Digi-Comp II for MIT, which we’ll be posting about in the near future. Today, MIT computer science professor Scott Aaronson published a short “paperlet” about the computational capabilities of the Digi-Comp II on his blog, Shtetl-Optimized:

…it’s amazing that such a simple contraption of balls and toggles could already take us over the threshold of universality.  Universality would immediately explain why the Digi-Comp is capable of multiplication, division, sorting, and so on.  If, on the other hand, we don’t have universality, that too is extremely interesting—for we’d then face the challenge of explaining how the Digi-Comp can do so many things without being universal.

Ingenious 1970′s Technology: The Flip Flash

FlipFlash 5

Once upon a time, cameras did not come with LED illumination or even xenon strobes, but rather with a socket that could fire a one-time-use flashbulb.

An advance from this was the “flip flash” cartridge which held 8 or 10 flash bulbs, ganged up so that you could take one photo after another, without pausing to swap bulbs. Each time that you took a picture (exposing actual film!), the next flashbulb in the cartridge would fire.

But you might ask a tricky question here: How does it know which bulb to fire next?

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555 kit, version 2.0

555 Kit v 2.0

Today we’re introducing version 2.0 of our “Three Fives” Discrete 555 timer kit.  Version 2.0 has a number of little tweaks and improvements, with a cleaner design and — coolest of all — an all-new set of smooth anodized aluminum legs.

555 Kit v 2.0

The Three Fives kit is a faithful and functional transistor-scale replica of the famous 555 timer integrated circuit — one of the most popular and well-loved chips of all time. (An original NE555 IC is shown above for scale.)

We are also releasing the first version of our educational supplement for the Three Fives kit: A detailed description of how the 555 circuit actually works, with plenty of opportunities for further exploration.  You can find it on the downloads section of the product page or on our documentation wiki.

 

 

The Decoregger

Decoregger 1

Hey look! It’s the fossilized remains of a possible evolutionary ancestor of the EggBot!

Decoregger 2

Okay, it’s pre-USB but technically it’s not a fossil. Like many of us, the decoregger dates from the mid-1970′s. It’s a simple function gadget that mounts an egg so that you can spin it, with arm second arm that holds tiny felt-tip pens.  Curiously, there are also some contemporary machines bearing the same name that lack the separate arm.

 

Decoregger 3 Decoregger 4
Decoregger 5 Decoregger 6

In the upper-left photo, you can see that the pen holder has a separate “paddle” that you hold, to manually move the pen in the arc across the egg surface.  Lacking the proper felt-tip pens, we found that a uni-ball micro pen was about the right diameter to fit in the holder.

One surprising thing: To model this thing, we used regular “large AA” (not extra large, and not jumbo) size eggs from the grocery store. And it was only barely possible to squeeze the egg into the holders. From the picture on the box, it looks like there’s plenty of room for even the largest egg.  Possible explanation #1: Plastic shrinks over time. Possible explanation #2: The egg pictured on the box is from the advertising land of freaky micro-children.

But in any case, the decoregger is a cute little machine, and it looks like it might be fun to play with.  The actual play is a matter of turning knob 1 and knob 2, so it feels a lot like an Etch-a-Sketch in spherical coordinates. Now if only there were some way to strap a couple of motors to it and perform a CNC conversion….

Decoregger 8

Speaking of which, it really is a lot smaller than the EggBot.  Heck, you could probably fit the whole thing inside the EggBot.

Decoregger 7

Wait — am I doing this right?

Special thanks to Michelle Hlubinka for finding this artifact and sending it to us!

A Vintage Bliley Crystal

Bliley Crystal 1
Bliley Crystal 2 Bliley Crystal 4
Bliley Crystal 7 Bliley Crystal 6

They don’t make — or package — them like they used to. This is a vintage radio crystal from the Bliley Electric Company.  Bliley is still around, making modern oscillators and even space flight hardware, but this vintage unit is a beauty.

Introduced in the 1930′s, the Bliley LD2 was a popular frequency standard for amateur radio operators. A 1935 advertisement in QST magazine claimed efficiency and extremely low drift (<8 ppm/°C), guaranteed operation, an improved holder, and a cost of only $4.80, or $82.79 in 2014 dollars.  This particular unit is calibrated at 3.9895 MHz (“3989.5 KC”), for a radio wavelength of about 75.2 m.
Bliley Crystal 9

 

Unlike most modern crystals, this type comes apart easily. Inside, two rectangular steel plates sandwich a thin slice of quartz crystal, all held pressed together with a simple spring.

If you’re interested to learn more, there’s a wealth of additional information about vintage crystals and the Bliley company available online, here.

Erector Rocket Launcher Set

Erector-Rocket 2

We recently acquired this beautiful Erector Rocket Launcher Set from 1958. While not quite complete, it is still tantalizing with its girders, nuts, bolts and motor. The printing on the metal box is beautiful.

Erector-Rocket 4

The motor is labeled “Erector Electric Engine” and features a clever mechanical gear shifter.

While our set did not come with instructions, there are online resources for vintage building sets, and Girders & Gears has a thorough description and pictures of a more complete set. They also have instructions available for download, which include the following practical warning:

CAUTION: Be sure there is no one in front of the launcher when the rocket is fired.

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.