Podtique: podcast player in an antique radio

Podtique: Antique Podcast Player

Our friend Rick stopped by to show us his latest project, which he calls Podtique: a podcast player built into an antique radio cabinet. Using the original knobs, you tune in on “stations” which play different podcasts, with realistically generated static in between.

Podtique

The whole thing is run on a BeagleBone Black, and uses NeoPixel backlighting behind the dial. He’s written up the build on his blog, posted his code on github, and shared a heap of build photos in an album on flickr.

A Vintage Melody Synthesizer IC

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Leigh Klotz, author of Ham Radio for Arduino and PICAXE, gave us this interesting chip from the 80′s to play with: a UM3482A “Multi Instrument Melody Generator” IC.  While not quite rare, it is a bit of a vintage curiosity these days, and we wired one up to see what exactly it does.

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The vintage Radio Shack Archer package it came in was minimalist (though not quite this minimalist as it came to us– imagine that the chip were still there in the bubble). It promises not just 12 tunes, but circuit diagrams as well.

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This Archer-branded datasheet (including the promised circuit diagrams) came stapled to the back.  You can download a readable copy of the manufacturer’s original datasheet here.

“A mask-ROM-programmed multi-instrument melody generator, implemented in CMOS technology. It is designed to play the melody according to the previously programmed information and is capable of generating 12 songs with 3 different effects: piano, organ, and mandolin.”

Amongst the twelve musical selections are London Bridge, Row Row Row Your Boat, Oh My Darling Clementine, and (of course) Happy Birthday.  Suggested applications included toys, door bells, music boxes, and telephones.  (File under: Customized ringtones of the 80′s?)

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The three little graphs in the upper right show the three different timbres (the “instruments,” in the phrase “multi-instrument”) in terms of amplitude versus time. The other diagrams show how to wire it up to a speaker and how to configure the various inputs to select which song to play and so forth.

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We breadboarded up a sample circuit from the datasheet, substituting with parts we had on hand, including a little magnetic buzzer as the speaker. A 2xAA battery holder is connected up to the power and ground rails.  There is a momentary button switch to select the next melody in the set, and a row of DIP switches to set the configuration options.

And sure enough, it plays melodies.

LED Metronome


After seeing our Larson Scanner kit, Martin shared this LED metronome project with us. Martin says:

It was designed as a “Visual Metronome”  So a learning music student could help see the timing by watching the green light.  There was to be an optional clicking sound  by using a small solenoid for the ticking – I chose that in place of a speaker for a more authentic sound.

The timing is a standard 555 timer which is fed to 7442 BCD to DECIMAL counter.  Next chip is a 74193 UP/DOWN counter.  When the count hits the last number, it sends a pulse to reverse the count or start over – depending on the toggle switch on the side.

There is also a pot on the 555 to control the speed.  All this was made in one night while I was working the graveyard shift.

The entire LED display was hand wired using a manual wire-wrap tool.

The chip pin labels on the back of the perf board are a particularly awesome relic of a different era of electronics assembly. Thanks for sharing your project photos and video with us!

Modern manufacturing for vintage autos

Both mirrors

Last year, I wrote about a case of 3D printed parts being used for a vintage car. This year, another fine example of modern manufacturing and prototyping techniques being used for a vintage vehicle showed up on my doorstep when my parents stopped by during a road trip in my dad’s 1934 Dodge Brothers pickup

Passenger side mirrors on cars and trucks used to be a luxury, add-on, or aftermarket item— if they were even available at all. My dad’s truck never had one. In the intervening years, many states have made side mirrors a requirement, and having them makes safely driving a vintage vehicle much easier. So how did he get the matching one you see in the picture above?

Passenger side mirror

He did what pretty much anyone can do these days: he had the driver side one 3D scanned, had a CAD model made up from the scan and then mirrored it. The model was then 3D printed and sand cast in aluminum. After some finishing work and paint, it looks fantastic.

Side mirror mount showing standoff

However, geometry reared its head: it turns out that because the driver sits on one side of the car, a perfectly mirrored mirror mount doesn’t put the mirror in quite the right place. As a temporary fix, he added a standoff to correct the position of the mirror. After returning from the road trip, he’ll adjust the CAD model and have a new one printed and cast. Since the world of vintage cars is a close-knit one, he has already had requests for additional units from friends in the community, and making more will be straightforward from the digital master.

He’s had a few other components made using scanning and digital manufacturing techniques, including a laser cut insulation board for between the engine compartment and the cab. These techniques are a perfect fit for a community with low-volume needs for custom, unavailable, or never before made parts.

Soldering Tip Tinning with Sal Ammoniac


If you solder, you’ve likely come across an “untinned” tip at some point— that’s when the tip of your soldering iron loses its shine, and doesn’t easily wet to solder any more.

Once your tip gets this way, it doesn’t make nearly as good of a thermal contact to whatever you are trying to solder, and it simply doesn’t work well. Soldering can take 2-10 times as long, and that isn’t good for your circuit board, components, or mental health.

You can sometimes re-tin the tip by melting fresh solder onto it, but that can be challenging, because the whole problem is that the tip isn’t melting solder. It’s particularly hard to keep tips tinned with modern lead-free solder, because it needs to get even hotter to begin melting.  If you get to this point, you might think about even replacing the tip.

But before you throw that tip away, instead consider using one of the “old standard” solutions, which is to refurbish the tip with a tip-tinning compound. And we came across the most classic of them in one of the most unexpected locations.  Continue reading

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

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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

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

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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.

 

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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….

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

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Wait — am I doing this right?

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