UptownMaker

  One of my favorite YouTubers made a video about his project to make a centrifugal dust separator for his woodshop. It's a clone of this  Harvey  dust collection system which, as of the time of this writing, retails for almost $2800US. Naturally, I had to try to make my own. I sized it to fit inside 4" PVC instead of the 6" diameter acrylic tube he used. I don't care about seeing the dust swirl inside and I wasn't about to spend $150 on the tube, either. Operation is pretty simple. Overall airflow is in the direction of the yellow arrow. Lighter dust follows the orange arrow and is spun up by the turbine (which does not actually spin, important to note), causing it to be flung to the outside of the pipe. Heavier dust can't make the corner around the initial stage, causing it to be dumped into the first stage collection bin. At first, I was using a couple of 5-gallon buckets as the collection reservoirs, and a battery powered Ryobi shop vac to do the air movem...

Chris Gammell, of  Chris Gammell's Analog Life  and  The Amp Hour ,  tweeted  about  this gizmo . Not surprisingly, it set off his bullshit sniffer, and mine too. So, let's do a tiny little bit of physics and find out if their claim to a fully charged iPhone battery in 2.5 miles is legit. First, the assumptions: 1. My mass is 75kg. I wish, but that's close enough. 2. My stride length is about 6 feet, so 3 feet per step. A little long, but probably close enough. That gives me about 4400 steps in that 2.5 mile walk. 3. I lift my foot about 10mm with each step. 4. An iPhone battery has about 1500mAh of battery life, which, for an average LiPo battery voltage of 3.7V, translates to 5.5wh, or approximately 20kj of energy required. For a standard gravity, 10mm step height, 75kg person, and W = f x d, we get 7.35j per step. 4400 steps gives us 32kj total generated; we need to capture 20kj of that to charge the phone. That's 62.5% of the energy generated. ...

Caveat lector--this post has nothing  to do with making anything. Except the aforementioned kerfuffle. First things first--I am absolutely aware of my privilege. I'm a cis, hetero white man, of unexceptional girth and slightly more than average height. I have no scars, no birthmarks, no differences of ability which would draw the eye. In short, I'm playing the Game of Life on the lowest possible difficulty level, and damn lucky for it. So. A few months ago (right before Hogswatch  Christmas), I decided to start painting my fingernails. I've always wanted to--or, at least, since I was at least a preteen--but I've never had the courage to do it. I'm not prone to an action such as this simply for attention or to be "different". I simply realized that, for the first time in my life, I was comfortable enough with myself and my life to scratch a long-denied itch. My beautiful wife bought me many varieties of polish, and I've been painting my...

I'll attempt a bit of subterfuge and obfuscation here so I don't inadvertently ruffle too many feathers... A friend just sent me a summary of the EE capstone projects from this year's crop of students at a university that shall go unnamed. Bright-eyed young engineers, fun problems, innovative solutions, yadda-yadda-yadda. Pretty much anyone reading this has a pretty good mental image of what might have been in the e-mail, and many of you LIVED it. But then, right at the end, was an incredibly troubling BTW: PS: professor's name here told me that he does not allow Arduinos to be used on these projects, since it makes things too easy (at this level of education, they're supposed to be learning the stuff that Arduino hides from you). Better he was there than me. I'd have lost my shit if an engineering prof said something like that to me. I get what he's saying- that the journey is the point, not the destination- it's just that for everything else...

Side note- it's been a looong time since I wrote a blog post. Since then, I've had a second child, moved jobs (I'm now working at SparkFun - woot!), states (Colorado is state number six for me), and time zones. A lot of the more technical sort of blog post I'd write now goes up on the SparkFun website as tutorials, but I'm going to try to post more here. Engineers and scientists (and other general nerd/geek types) like to talk about "numeracy", which is the ability of a person to grok math. It used to be that the primary "complaint" (if you will) was about people who play the lottery- "a tax on being bad at math". I'm not talking about valuation, here- being willing to pay five- to tenfold as much for a meal at a restaurant as it would cost to make at home, for instance. I'm talking about hard numbers- apples to apples. Having a poor grasp on mathematics is getting to be a bigger handicap, though. I've notice recently wh...

I found this image on Google maps satellite images the other day. It's a E-3 Sentry taking off from Tinker AFB near Oklahoma City. At first I thought it was a KC-135 (and that's what it went out on Twitter as) but then I noticed the rotodome on top. It's neat because you can see the sequence of images as captured by the satellite. In the first "frame", it's just starting to pull away from the ground, and by the last frame it's well off the surface and past the end of the runway. You can also see the procession of the rotodome- the band of gray in the disk shows the rotation.

On the bus the other day, as I was rolling past waiting commuters on Marquette Ave in downtown Minneapolis, I saw a yawn traveling along through the crowd. Or at least, that was the appearance- it may have just been that people were randomly yawning as I passed. Regardless, that got me thinking: what is the propagation speed of a yawn through a given crowd? We should be able to express that as an equation, if we choose our parameters wisely. First, let's define "speed", for the purposes of this exercise, as the time required for a yawn to travel a given distance through a crowd in any direction. The reason for that wording will become clear later. So, that brings us to the equation: V = d * q * (m / r) * f(C) where d is the average delay between when a person sees a yawn start and starts yawning themselves m is some distance factor (it can be observed that someone closer is more likely to inspire a yawn than someone farther away- m will have to be determine experi...

So, I cast a fairly wide net in terms of things I passively track for potential food-for-thought. Blogs and tweeps, books, articles, etc- I try not to limit myself too much because I can skim pretty quickly across a fairly vast swath of content, even if it IS just a drop in the bucket. This morning, the following tweet came through, from Tim Hurson : To ourselves we are a complex of thoughts and feelings. To others we're just a bunch of behaviors. Really not engineering related, of course, but it meshed well with something else I saw come through my twitter stream- a post about Dunbar's number, which is the supposedly optimal group size of human culture: the number of people that you can conceivably know about and care about. That group of about 150 individuals is your monkeysphere , and people outside of it are, to some extent, not really people in your mind. I think there's a little more to that tweet than the 140 character limit allows. See, to people who consider y...

This past weekend I attended Maker Faire in San Mateo. It was an absolute gas (does anybody use that phrase anymore?)! I'm going to do a few quick posts highlighting my favorite sights- all my pictures and videos are on my Picasa site . I'll start out with my favorite first: Miss Haley Who, swamp kirin wrangler. This lovely fellow is a mechanical swamp kirin. He stands about nine feet tall and though he looks ferocious he's really quite gentle. Haley Who, aka halo seabat, built this majestic creature as a gift for her little brother, Seth. It seems Seth was a bit heartbroken after their father explained that the few remaining wild swamp kirins in the east were best left unmolested in their natural habitats, and halo took pity on her brother, building him this mechanical version. The pair of them wandered about the grounds, charming the pants off of just about everybody they met. Haley's disarming smile, the kirin's gentle gait and their tender interplay sof...

This was originally going to be my calling card for Maker Faire. It's a very simple implementation of Osamu Tamura's AVR-CDC project , realized without a board. I had planned to make it a small device that can be plugged into a USB port and observed on a terminal spitting out information about me. The Great Global Hackerspace Challenge project took a lot out of me, though, so I didn't get it done in time. The blobby on the left is an I/O module- three input switches, three output LEDs, and a reset switch and power LED. It plugs onto the header that is currently being used for programming. The circuitry is pretty simple: 100nF bypass capacitor, the 5V in from the USB port goes to the positive supply pin through a 1N4001, and the USB D+/D- are connected to a couple of the I/O pins. Some words about that 1N4001: it was chosen specifically for its high forward voltage. See, the USB input wants a 3.6V input or so, and the AVR doesn't want to run at the 16+MHz needed for t...

About two years ago I decided I was going to figure out a cheesy inductive power coupling circuit. I sat down one Sunday, started plugging some stuff together and this is what I ended up with: This is the circuit I brought with me to the "bring-a-hack" dinner at Harry's Hofbrau that Jeri Ellsworth organized on Sunday night. You can see that the LED in the jar is lit- the jar is really just a gimmick and the little parasite works better outside the jar. The circuit is very simple: the IC in the middle is a 12F683 that I programmed up to be a square wave generator (someday I'll blog that project, but for now, I'll just say that the oscillator frequency is jumper selectable and it can be set to either update constantly when powered or set and forget the output frequency and duty cycle) running at 50% duty cycle and (approximately) 71kHz. The square on the right is a bit of ~28ga magnet wire wrapped a few times around four screws. Power is delivered to it by a tr...

A friend of mine recently posted to Twitter a picture of an object that his 19-month-old identified as "K". That got me to thinking- clearly, she knows what a "K" is, but it doesn't exist in the "privileged class" of objects that we arbitrarily refer to as "letters". Hence, she was able to spot a "K" someplace an adult would never even look for one. At her age, she still sees nouns everywhere she looks. That doorstop LOOKS like a "K" so she identified it as such. As adults, we live in a world of verbs. We look at that object and see a doorstop- which is to say, we see what it DOES rather than what it IS . There's an important distinction there, for makers and artists especially. We tend to be so wrapped up in the verb form of the world that we forget the noun. My personal experience with this has also been that even when I succeed in considering an alternative solution to a problem, I STILL verb-ify my solution,...

Too busy to blog lately. I need to change that. Today I'll be doing lots of gateware builds on a project so I'll have some free-time. I attended a seminar last week about the picoPower capabilities of Atmel's UC3, Atmega and Xmega processors, and it got me hankering to start working with the Xmegas. It did not, however, give me a good answer to a fundamental question: what the heck is the difference between the 'A' and 'D' family of Xmega parts? Some Google searches failed to turn up a result, so being a good little creator of value, I thought I'd do the research and make a post about it. For more information about the Xmega in general, EMSL have a good starter article . In short, they are high-ish pin count, 3.3V microcontrollers that add some really nice features to those available in the Atmega parts. They come in two flavors- 'A' and 'D', with 44, 64 and 100 pin count devices and QFN, BGA, and QFP package options. They also have...

Elegant (adj.): “I’m being an unnecessarily clever d!ck about this, and that’s going to open up a lorry-sized hole in my design that I won’t see because I’m being too smug about how clever this solution is. Oh, and it’ll be harder to fix, understand, build, troubleshoot, and use, but I saved $.000001 on each unit by committing untold future resources to solving the problems I don’t know I just made. It also took far longer to design than it would have had I done it in a more conventional manner, but that’s okay, because design time is free and per-unit cost is king.” KISS is the alternative to "elegant", and frequently results in designs which are MORE elegant than trying to be clever produces.

No, not that first time (well, not exclusively). Think about the first time you did something that scared the hell out of you.  For me, the best example is the first time I set out to ride a rollercoaster and actually enjoy it.  Before, the tiny number of times I'd been on coasters were all profanity-laced panic-attack-like attempts to assert my masculinity.  This time, however, I decided to seize my fear and enjoy the ride.  It worked- that summer, and the two years thereafter, I bought a season pass to the local theme park and racked up literally hundreds of out-and-back trips, and I made a couple of special trips to other theme parks to hit THEIR coasters, too.  Something that had been previously unimaginable became a source of tremendous enjoyment to me. What about the first time you used a tool you'd never used before?  I was terrified of the vertical milling machine until the first project I used it for; now I can't imagine NOT having access to it...

I've long suffered from notebook envy.  Not envy of any particular notebook; I just always wished I could be one of those people that carries a notebook around and jots down notes on everything - stuff they want to look up, buy, make, write about, talk about, whatever. I never HAVE been one of those people, for a number of reasons.  I'm scatterbrained, so even if I did have a pen and notebook, they'd have to be pocket-sized so I can not have to carry them around, or I'll lose them.  I hate writing (I actually have a mild learning disability which affects my ability articulate ideas with a pen and paper), so I'm not likely to be writing draft blog posts or a novel in my notebook.  I can't draw for crap, either, and I don't have much interest in developing that skill.  I also never found a notebook I really liked- they're too big, or too rigid, or the paper is too thin, or they are lined/gridded wrong.  I'm very Goldilocks on this. I like the Maker...

In mathematics, a degenerate form is one that cannot be perturbed in some way without being rendered a member of a larger, more complex class.  For example, a circle is a degenerate ellipse- change the constant multiplier of one of the terms and you push the form out of the class of circles into the larger class of ellipses. Next time you're solving a problem, ask yourself: am I solving for a degenerate form?  And, if the answer is yes, is that important?  Let me give an example where the answer to both questions was "yes".  I was tasked once with supporting some motion code which was intended to align a circuit board on a conveyor belt under a camera. The code as written worked fine in the lab, but in the field, customers began to complain of erratic and unpredictable behavior- boards which would be incorrectly positioned at the start of inspection, pushed off the end of the conveyor, etc.  It turns out that the code had originally been written to the dege...

Whenever you put a project out there in the community, be it on your blog, a community board, or as an article in another venue (or if it gets picked up by say, Hackaday or Make), you're bound to get some comments that are, shall we say, worth less than the calories they took to type.  Worse still are the times you get these comments from someone to whom you are explaining (in meatspace) your current pet project- those times can be a SERIOUS buzz kill and I've lost the will to finish a couple of projects after comments like this. "You know, Target sells something that [does that]/[does almost exactly that]."  This is more common in meatspace than on the web, I think, because the web audience self-selects for people who understand that the joy is in the making, not the having.  And, frequently, the "almost" is where the bugaboo lies- I want EXACTLY that, not ALMOST exactly that. "Arduino is for losers."  Or some variation thereon.  Arduino, as a p...

... as proposed by Jeri Ellsworth:  the "Jones", after EEVblog's Dave Jones. As with all SI units, we must define it in terms of base units, so I propose this: 1 Jones = (# of complaints about a topic) * (sum of levels of annoyance caused by said complaints weighted by exposure frequency to causative events, in seconds between exposures) * (# of people likely to be exposed to your ranting) Obviously, the level of annoyance varies from person to person; I imagine a level 1 annoyance ("mild eye rolling followed by repetition of action until desired result is achieved") for a more patient colleague might be a level 5 annoyance to me ("loud sigh with posture change and muttered profanity") and could rank to a level 100 for someone else ("widely distributed internet video rant with attendant behavioral change and increased probability of property damage to exact retribution on an inanimate object"). As a practical example I'll float m...

On the heels of a few tweets regarding linear voltage regulators that I passed with a friend yesterday, I think I'll do a couple of posts on voltage regulation. First, the general concept: voltage regulation is the creation of a stable, low-impedance DC voltage source from an unregulated DC voltage source.  Examples of unregulated DC voltage sources are batteries, "wall wart" type AC/DC converters (even though many of these create very good voltages (these days, anyway), you should always assume that you (or someone else) will plug a different supply in), car cigarette lighter sockets, rectified and filtered transformer outputs, solar panels, fuel cells, dynamos, and fruit with pieces of zinc and copper in.  In fact, pretty much anything other than a locally generated voltage from a well-designed regulator circuit should be treated as an unregulated source (for design purposes, at least). This first post will concentrate on linear voltage regulators.  Sometimes you...