UptownMaker

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. That strikes

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