USB Mix Tape

I was reminiscing with friends about the days of mix tapes when it struck me that the ubiquitous USB flash drive would fit almost perfectly into a cassette tape, making a perfect marriage of old and new media. You could have all of the artwork and label design potential of the tape (to say nothing of the nostalgia), but with the space for more than just a dozen songs.

A quick survey online found some instructions on making your own or even buying pre-made ones. Ignoring all, I plunged ahead. After all, this is about learning, building, and probably screwing up, not just having a finished product.

I found a cheap, unopened cassette tape at a local surplus store, but it turned out to not have the screw-joined halves I thought it would. I was going to have to raid my old stash of tapes from the corner of the basement. I haven’t listened to a tape in at least a decade, don’t even have a tape player, and certainly don’t still have the old Yamaha multitrack recorder these were recorded with, but I still had a tough time sacrificing it. Why, there could be a heartfelt masterpiece on that tape that 22-year-old me recorded. Someday the archivists (or prison psychologists) will want to study it!

Oh well.  Onward!  I at least chose one without a label, on the theory that if I hadn’t thought it worthy of labeling back then, it couldn’t be that important. Now we’ll never know.

With tape in hand, I needed a flash drive. I had a few laying around, so after disassembling the tape to see just how much room there was inside, I spent an hour or so trying out different drives for fit. I wanted the tape to retain its original profile, but I wasn’t sure whether the USB drive should slide out, swivel on this axis or another, or just present a port that would require a separate cable. The drive that seemed most promising was a 2GB SanDisk Cruzer and its sliding action; it would require the least modification to the tape and would be the strongest.

The donor drive, in and out of its original housing.

On a side note, I’m amazed by the fact that I live in a world where it’s hard to find a cassette tape, but I’ve got multiple gigabyte+ storage options buried in my junk drawer.  I remember when these cassette tapes used to be the storage for my computer. Three cheers for progress!

With a 3/16″ end mill I milled the port for the USB connector to slide in and out of. Then, after measuring and re-measuring more times than I can count and mapping out the exact numbers of turns and even which direction to turn the handles on the mini-mill (I’ve only had it for a month, and this was my first project after getting it set up), I plunged the mill into the tape and started cutting the opening for the sliding mechanism. I put the opening on side B of the tape, so that side A would look stock while it was in the case. All the planning worked out well, because when I popped the tape out of the vise, the drive fit perfectly.

Unfortunately, the two halves of the cassette didn’t quite fit together. If the SanDisk folks had made their drive just the smallest fraction of an inch thinner, it would have slid right in for a perfect fit. I was going to have to thin the cassette shell.

The finish is a little rough, but it works. You can see the opening for the slider, the thinning of the case, and the notch that keeps the drive locked into place when it’s all the way out. With side B milled out, I tried to put the two halves of the cassette shell together again. No luck, and side B couldn’t stand to lose any more plastic, so I did the same thinning on side A.

A test fit found everything sliding easily when it was supposed to and locking down when required, so I moved on to the reels next.

As you can see in the photo, the take-up reel got in the way of the memory. I attacked it with the belt sander and ground it down just barely to the inside sprockets, then glued it into place (below). It would have been nice to retain the tape functionality, but it wasn’t to be.

The spool of tape on the other reel was a little bit too large and kept the memory assembly from being able to slide all the way back. I didn’t want to unspool too much and lose the full-tape look, so I experimented with the spare tape I got from the surplus store and put some superglue across half of the reel. The thin glue quickly soaked in and glued the layers of tape solid enough that I was able to cut it right through with an X-Acto knife without it unspooling. The cut was a little rough, but that could be cleaned up. More detrimental was that it would be obvious from looking at the little crusts of dried glue through the tape’s window that it wasn’t quite right. Maybe something useful can be done with this tape-solidifying knowledge later.

So after that I decided it might not be so bad after all to lose the 1/4 inch of tape needed for clearance. Finally, a part of the project my four-year-old could help with: “Take this end and pull until I say stop!”

When our fun was over with, I threaded the tape back around the rollers and through the guides.

I know there are some problems with the tape path in this picture. I realized and corrected after the photo.

At last, I put the two halves in place and screwed them together. I didn’t have any labels for the tape, so I trimmed down an address label and used that, then plugged it in to the computer and reformatted to use the name “Mix Tape” (what else could it be?).

The drive works well on my laptop and in the USB port on my desktop machine’s keyboard, but because of the weight and leverage, I don’t know how it would hold up being unsupported in a port higher up on a desktop machine.

If I'd labeled it when I was 16 it probably would have had more stars, spirals, and other doodles on it than today's version.

Side A looks just like a standard tape, so much so that if it’s still in the case you’ll only notice the USB on the side if you look closely. I’ve handed it to a couple of friends, saying “I’ve got some music I want to share,” only to have them laugh and complain they had nothing to play it on. They have to be told to take it out and flip it over.

And now I have to go make some for them. That’s the trouble with making cool stuff.

Stormtrooper Neckwarmer

Can you not hit the broad side of a starship with a snowball?  Have you ever said “These aren’t the snowmen we’re looking for.”? If so, then this cozy Stormtrooper neckwarmer is just the thing to keep you warm while you’re hunting down enemies of the Empire on a crisp winter night.  Read on for instructions on making your own.

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Sewing the Core

With the core memory fabric finally in hand after the design process, what could I make? My first idea was a necktie, but having to cut that on the bias wasted a lot of fabric and the pattern ended up going the wrong way. My wife suggested a headband would look good, so I poked at a few of hers to puzzle out the construction, then got out the scissors.

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A Memorable Fabric

After my visit in May to the Computer History Museum in Mountain View, California, I was fascinated by the lattice structure of ferrite core memory. I thought it would make a great fabric pattern that was abstract enough to appeal to regular folk, but had a higher level of techno-geek meaning to it.

Read on for the story of how I went from the rough concept sketch above to a finished design printed by Spoonflower, an online service offering on-demand fabric printing.

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The Counting Box

My son—now four, but three when I conceived this project—loves numbers and counting. More than a few times I’ve peeked in at night to find him asleep with a calculator in one hand and a flashlight in the other. And one of his favorite things to do with the calculator is incrementing “1 + = = = = = = = = = =” until he can’t keep his eyes open any more. I decided to build him a dedicated machine that would do nothing but count up and count down.

My initial concept was simple: a seven segment LED display so it could be read in the dark,  a rotary switch in the middle to choose the value to operate with, and big buttons for adding and subtracting.  Green makes the number get larger and red makes the number get smaller.

Below is the finished product. Click the “Continue Reading” link under the picture for details about the process of building and programming. I didn’t take a lot of photos through the build process because there wasn’t much to see, so I’ll illustrate relevant parts of the writeup with photos of the finished counting box. Also, please be aware that this is meant more as a documentation of my build process and the things I learned, rather than as a step-by-step how-to guide to make your own. I hope you’re still able to learn something or be inspired.

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Snap Circuits Repair

For my birthday a few months ago I got the SC-300 kit from Snap Circuits, and it’s been a great way to share electronics with my son as well as having fun myself. Overall, I really like the set, but my biggest complaint is that I’d like to see more explanations of the circuits, rather than just the assembly guide it has now. Why use a 100Ω resistor instead of 100kΩ? What’s that transistor doing? Curious minds will be left wanting answers to questions like these.

But anyway, on to the repair…

The C1 piece, a .02μF capacitor, broke off at one of the legs. This is understandable, since the capacitor sticks out to be bent and squished accidentally by clumsy fingers.

If you look closely, you can see the broken right leg.

You can order replacement parts, but the shipping cost was prohibitive. Time to crack the case and peek inside! A fingernail and a small flat screwdriver (the size you might use to tighten screws on your glasses) popped the part open at the tabs without too much trouble, but be careful because if you crack the plastic that’s going to be a lot harder to repair than a wire inside.

Looks simple enough.

The local Radio Shack didn’t have any .02μF capacitors, but they did have .022μF. We had circuits to build right away, and it should be close enough for everything in the kit. If I feel like getting it exactly right later I’ll add a .02μF to the parts order for my next project.

Close enough.

The leads desolder easily, but be sure you don’t keep the heat on too long or you might melt the plastic directly underneath. Put the new part in through the holes in the case, bend the leads, then trim them to fit the tabs. The tabs don’t have any holes for the leads to go through, so just hold the lead onto the existing solder and heat it up. When it was done, the bottom half of the case clipped right on and we were back in business.

All fixed up and good as new.

Screen Printing Press

After doing some freezer paper printing* on a shirt for my son, I wanted to do some more intricate designs and maybe even sell some of them, but didn’t want to spend a lot of money buying a press. So what do I do instead? Spend a lot of money building a press!  Click the “continue reading” link for some details on the construction of my homemade screen printing press.

*cut a stencil in some freezer paper, iron it onto a shirt, dab on ink, pull up the stencil, set the ink with an iron.

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That Old Computer Smell

As part of a trip down to the Bay Area Maker Faire last month, my friend Kirk and I stopped at the Computer History Museum. From the exquisite machining of the operational Babbage Difference Engine, to the switches and blinking lights of 60s big iron, to the first-generation personal computers I grew up with, it was well worth the admission price.

The nostalgia was thick, with phrases like “I had that!” (Apple ][ and countless games) or "I so wanted one of those!" (Tomy Omnibot 2000) leaving my lips countless times.

But more than the sights and the sounds, what really hit me was the smell. The scent of some of those old computers instantly took me back to hours spent as a child digging through my mom's old camera equipment. Same smell in both cases. I don't know what it is—something in the finish, the circuit boards, the wire insulation, maybe the tiniest hint of mildew? If someone could distill that smell, I'd spritz it on the DSLRs I've got now in order to make them smell like real cameras should. Hell, I'd wear it myself.

Organizing the Resistance

I’m trying to set up a beginner’s electronics workbench, but organizing all of the components has been a hassle. I’ve got a cabinet with sixty-something little plastic drawers, but that seems inefficient for resistors when I might only have 5 of a particular value. It works well for other pieces like switches, buttons, and connectors, though.

I tried using small plastic envelopes in a recipe organizing box, and while it was nice being able to see them when an envelope was out on the desk, the envelopes were too floppy and it was impossible to flip through and find what I was after.

Then I remembered an unused two-drawer card file tucked away at my parents’ house that would be ideal. A2 envelopes were a perfect fit, and there was a sliding backstop in each drawer to keep it all packed tight.

Being a newbie to this electronics thing, I hadn’t yet memorized the resistor color codes, so I decided to print a color guide on each envelope along with the numeric value. The funny thing is that by making all of the envelopes in InDesign I’ve gotten pretty good at the color code system. I think they’ll still serve well as a check when I’m putting resistors back after a prototyping session.

The other night, with the envelopes all printed, I huddled over the piles and started sorting. First lesson learned: good light is a must. Under my lamp, red looked the same as orange looked the same as yellow. Brown and black? No difference between them! Eventually, with a few illuminations from a super-bright flashlight and a few particularly troublesome ones set aside for the morning, I got everything in its place and filed away.

Here’s the finished system. The resistors only take up about half of one drawer. What should I keep in the second drawer?

The Inadvertent Shipping Test

For a while I’ve wondered what kind of shape the neckwarmers were in when they arrived at their destination. Were they crumpled, wrinked, was the packaging torn?  In the back of my mind I had an idea to ship one boxed to family on the east coast then ask them to mail it back in the standard shipping bag, but I never got around to it.

But I found out today in a big way when a Christmas package meant for Australia was returned for having an insufficient address. That’s about as far as anything could be sent, and then doubled for the return trip. It was shipped on the tenth of December, and marked “Return to Sender” on January 5. I’m not sure when it arrived down under or how long it was kept, but it only got back to me here today. That’s over three months on the road — a far more rigorous test than I could have devised!

It's pretty smooshed up. Good thing there's only fabric inside.

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