Lean Thinking Helps STEM Kids Build a Tiny Windfarm

When we see a new build by [Gord] from Gord’s Garage, we never know what to expect. He seems to be pretty skilled at whatever he puts his hand to, with a great design sense and impeccable craftsmanship. You might expect him to tone it down a little for a STEM-outreach wind turbine project then, but when you get a chance to impress 28 fifth and sixth graders, you might as well go for it.

98j6zpStarting with an idea from his daughter’s teacher for wind turbines each kid could make, [Gord] applied a little lean methodology so the kids would be able to complete the build in the allotted time. The design is simple – a couple of old CDs holding vertical sections of PVC tubing to catch the breeze and spin neodymium magnets over four flat coils of magnet wire. It’s enough to light a single LED and perhaps a kid’s imagination.

As simple as the turbine is, the process of building it needed to be stripped of as much unnecessary work as possible, and [Gord] really shines here. He built jigs and fixtures galore, pre-built some assemblies, and set up well-organized workstations for each step of the build. Everything was clearly labeled, adult volunteers were trained using the video after the break, and a good time was had by all.

Sometimes the hack isn’t in the product but in the process, and [Gord] managed to hack a success out a potential disaster of disappointed kids. If getting a taste of [Gord]’s style makes you want to see more, check out his guitar fretting jig or his brake rotor mancave clock.

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A No-Solder, Scrap-Bin Geiger Counter for $15

Scenario: your little three-hour boat tour runs into a storm, and you’re shipwrecked on a tropic island paradise. You’re pretty sure your new home was once a nuclear test site, but you have no way to check. Only your scrap bin, camera bag, and hot glue gun survived the wreck. Can you put together a Geiger-Müller counter from scrap and save the day?

Probably not, unless your scrap bin is unusually well stocked and contains a surplus Russian SI-3BG miniature Geiger tube, the heart of [GH]’s desert island build. These tubes need around 400 volts across them for incident beta particles or gamma rays to start the ionization avalanche that lets it produce an output pulse. [GH]’s build uses the flash power supply of a disposable 35mm camera to generate the high voltage needed, but you could try using a CCFL inverter, say. The output of the tube tickles the base of a small signal transistor and makes a click in an earbud for every pulse detected.

You’ll no doubt notice the gallons of hot glue, alligator clips, and electrical tape used in the build, apparently in lieu of soldering. While we doubt the long-term robustness of this technique, far be it from us to cast stones – [GH] shows us what you can accomplish even when you find yourself without the most basic of tools.

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Forrest Mims, Radio Shack, and the Notebooks that Launched a Thousand Careers

There was a time when Radio Shack offered an incredible variety of supplies for the electronics hobbyist. In the back of each store, past the displays of Realistic 8-track players, Minimus-7 speakers, Patrolman scanners, and just beyond the battery bin where you could cash in your “Battery of the Month Club” card for a fresh, free 9-volt battery, lay the holy of holies — the parts. Perfboard panels on hinges held pegs with cards of resistors for 49 cents, blister packs of 2N2222 transistors and electrolytic capacitors, and everything else you needed to get your project going. It was a treasure trove to a budding hardware hobbyist.

But over on the side, invariably near the parts, was a rack of books for sale, mostly under the Archer brand. 12-year old me only had Christmas and birthday money to spend, and what I could beg from my parents, so I tended to buy books — I figured I needed to learn before I started blowing money on parts. And like many of that vintage, one of the first books I picked up was the Engineer’s Notebook by Forrest M. Mims III.

Wish I could find my original copy from 1979. This one is on Amazon.
Wish I could find my original copy from 1979. I just bought this one from Amazon.

Many years rolled by, and my trusty and shop-worn first edition of Mims’ book, with my marginal notes and more than one soldering iron burn scarring its pulp pages, has long since gone missing. I learned so much from that book, and as I used it to plan my Next Big Project I’d often wonder how the book came about. Those of you that have seen the book and any of its sequels, like the Mini-notebook Series, will no doubt remember the style of the book. Printed on subdued graph paper with simple line drawings and schematics, the accompanying text did not appear to be typeset, but rather hand lettered. Each page was a work of technical beauty that served as an inspiration as I filled my own graph-paper notebooks with page after page of circuits I would find neither the time nor money to build.

I always wondered about those books and how they came about. It was a pretty astute marketing decision by Radio Shack to publish them and feature them so prominently near the parts — sort of makes the string of poor business decisions that led to the greatly diminished “RadioShack” stores of today all the more puzzling. Luckily, Forrest Mims recently did an AMA on reddit, and he answered a lot of questions regarding how these books came about. The full AMA is worth a read, but here’s the short story of those classics of pulp non-fiction.

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3D-Printed Strain Wave Gear Needs Your Help

In most mechanical systems, metal gears that bend are a bad thing. But not so for strain wave gearing, which is designed to take advantage of a metal gear flexing to achieve an action much like planetary gears. The fun isn’t limited to metal anymore, though, if you 3D print a strain wave gear like this.

Strain-wave gearing is nothing new – it was invented in 1957 and has traveled to the moon on the lunar rover. And you may recall [Kristine Panos]’ recent article on a LEGO strain wave gear, which makes it easy to visualize how they work. She also has a great description of how the flex spline, wave generator, and circular spline interact, so we’ll spare those details here. [Simon Merret]’s interpretation of the strain wave gear is very simple and similar to other 3D-printed versions, except that he uses an inside-out timing belt as the flex spline. The wave generator is just an arm with a roller bearing at each end, and despite needing a few tweaks the gear does an admirable job.

Simon is reaching out for help in getting this gear ready for use where the industrial versions see frequent application – the first and second degrees of freedom of robotic arms. If you’ve got any ideas, head over to his project page on Hackaday.io and pitch in.

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LED Strip Display Gives You Two Ways to See the Music

What to call this LED strip music visualizer is a puzzler. It lights up and pulsates in time with music similar to the light organs of 1970s psychedelia fame, but it’s more than that. Is it more like the Larson Scanner that graced the front of [David Hasselhoff]’s ride on Knight Rider? A little, but not quite.

description-croppedWhatever you decide to call this thing, it looks pretty cool, and [Scott Lawson] provides not one but two ways to build it. The business end is a simple strip of WS2812b addressable LEDs. It looks like the first incarnation of the project had an ESP8266 driving the LEDs in response to commands sent to it from a PC running the visualization code, written in Python. That setup keeps the computationally intensive visualization code separate from the display, but limits the display to 256 pixels and probably has to deal with network latency. The Raspberry Pi version both crunches the numbers and drives the display, but the Pi doesn’t have the oomph to run both the LEDs and the GUI, which is pretty interesting to look at by itself. The video below shows the different visualization modes available — we’re partial to the “energy effect” at the end.

Take your pick of hardware and throw a couple of these things together for your next rave. And if you need a little more background on the aforementioned Larson Scanner, we’ve got you covered.

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Sculptural Nixie Clock has Shockingly Exposed Design

Single tube Nixie clocks? Been there, seen that. A single tube Nixie clock with sculptural wiring that exposes dangerous voltages? Now that’s something you don’t see every day.

[Andrew Moser]’s clock is clearly a case of aesthetic by anesthetic — he built it after surgery while under the influence of painkillers. That may explain the questionable judgment, but we won’t argue with the look. The boost converter for the Nixie lives near the base of the bent wire frame, with the ATmega 328 and DS1307 RTC supported in the midsection by the leads of attached passive components and jumper wires. A ring at the top of the frame supports the octal socket for the Nixie and a crown of driver transistors for each element.

In the video after the break, [Andrew] speaks of rebuilding this on a PCB. While we’ve seen single tube Nixie PCB clocks before, and we agree that the design needs to be safer, we wouldn’t ditch the dead bug style at all. Maybe just throw the whole thing in a glass bell jar or acrylic tube.

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Microfluidics “Frogger” is a Game Changer for DIY Biology

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See those blue and green dots in the GIF? Those aren’t pixels on an LCD display. Those are actual drops of liquid moving across a special PCB. The fact that the droplets are being manipulated to play a microfluidics game of “Frogger” only makes OpenDrop v 2.0 even cooler.

Lab biology is mainly an exercise in liquid handling – transferring a little of solution X into some of solution Y with a pipette. Manual pipetting is tedious, error prone, and very low throughput, but automated liquid handling workstations run into the hundreds of thousands of dollars. This makes [Urs Gaudenz]’s “OpenDrop” microfluidics project a potential game changer for the nascent biohacking movement by offering cheap and easy desktop liquid handling.

Details are scarce on the OpenDrop website as to exactly how this works, but diving into the literature cited reveals that the pads on the PCB are driven to high voltages to attract the droplets. The PCB itself is covered with a hydrophobic film – Saran wrap that has been treated with either peanut oil or Rain-X. Moving the droplets is a simple matter of controlling which pads are charged. Splitting drops is possible, as is combining them – witness the “frog” getting run over by the blue car.

There is a lot of cool work being done in microfluidics, and we’re looking forward to see what comes out of this open effort. We’ve covered other open source efforts in microfluidics before, but this one seems so approachable that it’s sure to capture someone’s imagination.

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