Back To My Roots

December 13, 2008 at 1:59 am (Cool Tech, General) (, , , , , , , , )

mai_tubeBefore I was dragged by circumstances into the world of Web 2.0, I started my geek life as a hobbyist. And I am terribly, terribly ancient; when I started being an electronic hobbyist, there were no “software” hobbyists. I was totally hardware. Soldering iron, screwdriver, and pliers, baby.

So last weekend, feeling a bit of a lack in my life, I decided to get away from the keyboard for a bit, and take up tools to craft a charger for my MP3 players. I find it tiresome to have to charge them off my PCs, and since I have all these parts lying about in my junk boxes and in the shed, why not build my own USB charger?

Let us begin…

…with an empty Altoids tin. This lovely, inexpensive steel box is easily drilled and cut, provides mechanical protection, electrical shielding, and heat dissipation, all in one. Plus a curiously strong minty freshness for the project.

Here you see the pile of parts I collected for the project, including the aforementioned Altoids tin, a USB connector salvaged from an old PC motherboard, a cheap cell phone charger, a solid state 5 volt regulator, a socket for the regulator (that’s the green & silver whatsit), a red LED for the little pilot light (letting me know it’s on and functioning), a couple capacitors (to smooth the voltage a bit), and a couple parts I didn’t use – a rectifier and a smaller 5 volt regulator. I included them in the pic for reference. Click here for a complete parts list. And click here for a schematic.

I started building up 2 of these USB chargers. The 2nd one isn’t finished yet. My engineering and design is done “on the fly” and I had to change course a little as I went. This photo shows the regulators mounted with their sockets in the Altoids tins.

The next image shows the mounting of the USB connectors. Using a utility knife, I was able to cut a rectangular hole in the sheet metal, in a sort of sideways “H” pattern. This left me with two tabs I could bend back into the tin, which I could use to attach the USB connector. You’ll see how in a subsequent shot.


Now, with the cover open, you can see the major parts installed. On the left, a small power jack – same size as a headphone jack on an MP3 player. To the right of that, you see the regulator and socket, and on the right, the USB connector, soldered to the tabs I mentioned. Nice and sturdy!


Sharp-eyed visitors will note that there seems to be something funny with the “input / output” labels. They look Photoshopped, and that’s because… they are. When I first used my Sharpie to mark the terminals, I got them swapped because the data sheet I downloaded was a little unclear. I got it sorted out later. But the ground symbol was on the correct terminal all along! 1 out of 3 ain’t bad. Same average I am currently running with “Sex, drugs, and rock & roll”. You figure out which one. Here’s a hint – the radio is on.

usbcharger7thumbnailAnd here it is – the finished project! The cell phone charger was replaced by the wall bug from an old answering machine. The cell charger didn’t have enough voltage or current to “git ‘er done”, so – course correction. On the left side of the box, you can see the plug-in jack for the adapter, and on the bottom of the box, you can kinda see the pilot light peeking out.

Next pic shows the final project, cover open, adapter connected. You can see the capacitors in place, all the wiring, the LED pilot light, and its 270 ohm dropping resistor, connected to the 5 volt output. Looks simple, huh? Well, try this at home – I dare you! Don’t burn your fingers with the soldering iron. I generally pick it up by the “cord end”, sort of thing.

This final image shows the unit under power. The pilot light is glowing merrily and a laptop light is plugged into the USB jack, to demonstrate that the unit is, in fact, delivering a well-regulated 5 volts to the USB device plugged into it. You can also see the regulator mounted to the outside of the tin.


And there you have it! The project gave me about 4 hours of very enjoyable hobby time overall, not including some time hacking on the little cell charger, trying unsuccessfully to get more “oomph” out of it.

No uneaten Altoids were harmed in the creation of this project.

altoidsthumbdrivethumbnailAnd it makes a nice companion to my Altoids USB thumb drive. I had a nifty little USB MP3 player which I accidentally fried during another hardware project, but the flash drive part was still working. So I stripped off the display and its PC board, and wrapped the memory stick part in electrician’s tape. But that’s not a very sturdy solution.

Eventually, I decided to use an Altoids gum tin as an enclosure. First, I cut a slot at one end for the USB connector. Then some double-stick foam tape and hot melt glue mounted the thumb drive circuit board to the box, and we’re good to go.


I marked the capacity inside the lid, and as you can see, there is still room left over for some Post-It flags and a place to store the protective cap from the connector.

Altoids style, my friends! Go thou now, and do likewise. Make a project with an Altoids tin, or some similar metal box, for yourself or a loved one. It’s a lot of fun, and it can take you back to your creative roots.

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