Archive for the 'hardware' Category

Tuesday, February 26th, 2019

New maker project — retro name badge

If you played pinball in the 80s, you know about 16-segment LED displays. They existed in the narrow technology window after mechanical switches and alarm-clock-style 7-segment displays, but before full dot-matrix displays or full video were feasible with off-the-shelf computer hardware. There’s something geekily charming about these old displays.

16 segments allow all alphabetic characters to be rendered…for the most part.

So naturally, I wanted to have a name badge made from these for FOGcon, which was 8 weeks away when I started this project. I would, in 8 weeks, conceive, design, construct, and debug a name badge based on this technology. With a professional printed circuit board. And a custom-programmed 32-bit microcontroller. All powered by a USB power bank.

You can find all kinds of electronic gadgets on Indiegogo and Tindie, but these pitches are always shown in the rosiest light. Seldom do you get a real-time view into a project, including all the little missteps and backtracks that are part of any maker project. Well, watch on.

Check out these videos for progress, starting with the schematic, revising it, creating a printed circuit board in KiCad, and revising it, then sending it off to get created, writing the code, and final assembly and debugging. Fun!

Part 1:
Part 2:
Part 3:
Part 4:
Part 5:

All the parts in a playlist

Since I ordered the PCB in a 10-pack, there are going to be extras to give away to Patreon and YouTube subscribers.

Please subscribe to my channel for the latest progress! -m

Wednesday, August 11th, 2010

Geek Thoughts: hard to find

Found this article interesting. Not too many hundreds of years ago, cutting-edge scientific research involved watching balls roll down ramps. Making fundamental discoveries seems to be slowing down, or at least getting harder. As a consequence, we should expect more big discoveries from the sciences where the relevant technology follows a Moore’s-Law-like exponential growth trajectory. There may be some hope yet for fundamental, game-changing discoveries in computer science.

Best of all, perhaps, is the word “scientometrics”.

Thursday, December 17th, 2009

Steorn Orbo on display: analysis

So Steorn’s Orbo technology is on display in Dublin. They have multiple live video streams, but at the #3 view at this hour shows “Offline” and “The channel owner has prohibited viewing from this web page”. Public viewing hours run from 10a to 7p six days a week.

What is it? There’s a detailed exploded diagram (PDF) of the display model on their site. It shows a rotor assembly with three main rings. The bottom two each have 8 magnets mounted in pairs at 90 degree intervals, and the skinnier top ring has only four magnets in the same alignment. The orientation of the magnets isn’t shown. The rotor assembly spins inside a frame with four pairs of toroidal coils which line up with the bottom two rings. A separate pair of “pick-up coils” align with the top ring. No wiring diagram is included. Based on the term “pick-up coil” the top assembly looks like a generator. Spinning magnets past a pick-up coil would produce AC, so the rectifiers shown below turn the AC into bumpy DC. Meanwhile, energy flows into the system through the remaining coils.

Oh, and the “Battery D-Size”. They claim it is only being used for temporary storage, to smooth out the flow of energy, and that the device is producing three times the energy it is taking in. It goes without saying that choosing to include a battery in a display model is a terrible choice for someone trying to convince a skeptical public that the device is more than a funny-looking motor.

From pictures I’ve seen, the battery doesn’t look off-the-shelf. It’s probably a high-density lithium-ion unit with capacity similar to a D cell, maybe 12 Amp hours @ 3 volts. That’s 36 watt hours. The rotor assembly itself uses low-resistance bearings and has an overall smooth shape for low wind resistance, so the amount of energy needed to keep it turning is probably quite small. Let’s say 50 mW. Given those figures, the device could run continuously for 30 days without needing to generate one scrap of energy, even discounting the possibility of clandestine midnight battery changes and the like.

The way the system is set up, it’s difficult to establish a reliable measurement. What if you hooked up a meter to the circuit with the battery in it–which way would current be flowing?

Turns out that’s a difficult question. The current flow varies over time, which introduces all kinds of measurement difficulties. A few paragraphs back, we did a simple DC power computation with volts times amps. In AC circuits, its more complicated–the addition of inductance or capacitance to a circuit adds an element of temporary energy storage which causes the two to become out of sync, so a simple scalar calculation isn’t possible. You get in the realm of imaginary numbers and a mathematical construct called a phasor, which you draw as a simple 2d diagram. For non-sinusoidal currents, including that bumpy DC from a rectifier, the math gets even more hairy.

Is it really this hard? Yep. I wrote earlier comparing the situation to the three-body problem, most often applied to gravitaional systems, but EM analysis is even harder. Take into account magnetic fields, the interchange of electric current and magnetic fields, back-emf, and Lorentz forces operating at right angles instead of attraction along a straight line. It all gets fearsomely complicated, well past the “vector calculus just for fun” level I’m at these days.

What they’ve now publicly shown seems to be enough for a competent person to duplicate, figuring out which of the few possible permutations of electrical connections make sense. If the claims turn out to be true, expect to see independent validations springing up. But it’s not easy, so expect this interesting situation to continue to unfold over (at least) several months. If I were Steorn and wanted to speed the process up, I would ditch the battery and take steps to make it easier, not harder, to validate the demonstration.

Disclaimer: I am a member of “the 300”, and have access to the SKDB. I haven’t paid anything to nor been paid from Steorn. Information in this posting comes from only public sources. -m

Update: The official video here clearly shows the battery with the markings NiMH and 10000, which is the capacity in mAH. So my capacity estimate above was a little high, though still a good guess if it was a lithium ion cell.

But the Nickel Metal Hydride battery raises other issues: NiMH batteries are very sensitive to overcharging, which should happen if the device is dumping continuous energy into it. At best this means that the battery’s capacity will get quickly diminished, reducing effectiveness as an energy buffer (and at worst, it means boom).

Sunday, November 8th, 2009

High Temperature Superconductors

If this site is accurate, it’s now possible to have superconducting material at household freezer temperatures: 254k, or a tiny bit below 0F. From power lines to maglevs to supercolliders to energy storage, the potential applications boggle the mind. -m

Note: I’m having trouble finding independent verification of this, other than what appears to be re-hashes of the article. If you have any additional proof or refutation, please post it in the comments.

Wednesday, June 10th, 2009

The Inmates are Running the Asylum: review and RFE

The central thesis of The Inmates are Running the Asylum by Alan Cooper is dead on: engineers get too wrapped up in their own worlds, and left entirely to their own whims can easily make a product incomprehensible to ordinary folks. For this reason alone, it’s worth reading.

But I do question parts of his thesis. He (with tongue in cheek) posits the existence of another species of human, called Homo Logicus. Stepping on to an airplane, Homo Logicus turns left into the cockpit with a million buttons but ultimate control over every aspect of the plane. Regular Homo Sapiens, on the other hand, turn right and tuck themselves into a chair–no control but at least they can relax.

But if there was only one “species” of Homo Logicus, members (like me) would never experience usability issues in software created by fellow Logicians. But ordinary fax machines give me fits. The touch-screen copier at work instills dread in my heart. And the software I need to use to file expense reports–written by enterprise software geeks probably very similar to me–is a usability nightmare. Words fail me in expressing my disdain for this steaming heap of fail.

The book is sub-titled “Why High-Tech Products Drive Us Crazy”, but one doesn’t have to look very far to find similar usability bugs in the low-tech world. Seth Godin, for example, likes to talk about different things in life that Just Don’t Work, along with reasons why. Some examples:

  • airport cab stand (75 cabs, 75 people, and it takes an hour)
  • “don’t operate heavy machinery” warning on dog’s prescription medicine
  • excessive fine print on liability agreements–intentionally hard to read and figure out
  • official “Vote for Pedro” shirts that look nothing like the ones in the movie
  • more examples on the web site

If anything, I think Cooper’s work doesn’t go far enough. It is relatively short on good examples, stretching out only four examples over four chapters. If properly-designed software is so hard to come up with examples of, then there are bigger problems in play (that would need to be dealt with by something more manifesto than book).

The book now 5 years old. Perhaps it’s time for an update. Particularly in the world of web software, lots has happend in 5 years. Flickr. Gmail. Yahoo Pipes. Google Docs. Even SearchMonkey. Instead of focusing on pointing at crappy software, I’d like to see more emphasis on properly-done interfaces. More delving into nuance, and common factors behind why both high-tech and low-tech products miss the mark.

But maybe that’s just me. -m

Sunday, April 19th, 2009

You know cold fusion must be hot when…

60 Minutes covers it. Disclaminer: haven’t seen it, the video doesn’t even play in my browser. Let me know if you have better success in viewing. -m

Friday, March 13th, 2009

Lithium battery breakthrough means your phone will charge in 10 seconds? Not so fast.

[Update: now featuring Actually Correct Math. Somebody stop me before I late-night-blog again…]

Recent news coverage mentions a badly-needed breakthrough at MIT in battery technology. Using a slight variation of existing lithium materials, much faster charge and discharge rates are possible. The money quote is that

[Professor Gerbrand Ceder and graduate student Byoungwoo Kang] went on to make a small battery that could be fully charged or discharged in 10 to 20 seconds.

News outlets seem to have latched on to this part of the announcement and hinted that all kinds of battery-powered devices will soon be chargeable in ten seconds. I don’t think it will be likely to see, say a cell phone (much less a vehicle, as some stories hint) that can fully charge in 10 seconds. Here’s why: A typical cell phone battery might be rated at 800 mAh. It’s not perfectly linear, but you can think of it as being able to deliver 800 milliamps for an hour, or 10 milliamps for 80 hours, and so on. You could approximate the energy storage of the battery by multiplying volts x amps x hours, giving a figure in watt-hours (in this case 3.6 x 0.8 x 1 = 2.88 watt-hr). To charge it in 10 seconds, all that energy would need to be delivered within the 10 seconds, which is a sixth of a minute, or a 360th of an hour. So the charging current would need to be 0.8 x 360 = 288 amps, not counting any efficiency losses in the form of heat.

What’s the big deal about pumping out 288 amps? Ohm’s law gives some idea. To push 288 amps through a complete circuit of one ohm (this includes the internal resistance of the battery), you would need to apply 288 volts, with a resulting power consumption of 288 squared, or just under 83,000 watts. That kind of current is more suitable for an industrial arc welder than a household battery charger. Even if the resistance can be made smaller, the benefit is only linear. To compare, my laptop, which dissipates 65 watts over several square inches, gets uncomfortably hot. Or see how long you can hold your hand on a lit 100 watt incandescent bulb. I can’t imagine packing that much energy into a “small” battery. It’s also hard to imagine a safe charging circuit that uses voltages that much above the nominal voltage of the battery.

So professor Ceder’s breakthrough looks great, and probably will be in iPods in a few years, but take the media coverage with a large grain of salt.


Monday, January 5th, 2009

T.V. Raman in the New York Times

My friend and XForms conspirator T.V. Raman was written up in the New York Times. (Link) [If the link happens to not work because of NYT’s stupid content policy, access the article via a search on Raman’s name on Google News.] Raman has done all kinds of great accessibility work that benefits everyone, photon-dependent or not.

Great picture too–love the closed laptop. -m

Monday, September 1st, 2008

Geek Thoughts: ballad

Blackberry singing in the dead of night

Take these calendars, and do invite

All your life

You are only waiting for this email to arrive

More collected Geek Thoughts at

P.S. Got a better one? Post it. -m

Tuesday, June 24th, 2008

dvorak difficulty: passwords

Day 3 and the first real difficulty: I can’t type most of my passwords except by muscle memory.

Overall, though, I’m enjoying the challenge, even if my postings are conspicuously short. :-) -m

Sunday, June 22nd, 2008

Going dvorak

I taught Anita some Python this weekend, and was peppered with questions like “where is the key for the two little lines?” “You mean a quote mark?” “Yeah.”

I’m going through much the same now. Moments ago I changed my keyboard layout to dvorak. Why? I type alot. Variety helps keep carpal tunnel at bay. And a few mental flexibility exercises definitely won’t hurt. (I’ll keep using qwerty at work.) Some observations:

  • “the” is really easy to type. It just flows out.
  • OSX has a key mapping that preserves qwerty layout when the cmd key is down–useful for muscle memory on cut, paste, open, close, tab, etc.
  • Expect more typos the next few weeks. :-)
  • ABCD is highly recommended.
  • Pointer fingers go on “u” and “h”. Without the little bumps on the keys, it’s hard to get your hands oriented. Two small pieces of tape help.
  • I’m getting better at this already.


Tuesday, June 17th, 2008

Yahoo! Mobile: outgunned and outflanked

According to Ars Technica, Google captured 61% of mobile search market share in the first four months of 2008. Yahoo! came in at a distant 18%, so pretty much reflecting desktop search market share. This is due, of course, to Google being the default provider on the iPhone, and the iPhone being the biggest bulk of mobile internet usage.

So Jerry (or whoever is on deck as CEO), you should probably look into this mobile thing and see what’s up with leadership there and whether anything is salvageable… -m

Thursday, May 15th, 2008

Power outage

I’m posting this during a power outage. Since I re-rigged my telecom setup with the Ooma box, I put all my telecom and internet boxes on a UPS. I’d been itching for a power outage to test it out. Temperatures are close to 100F today here, and with all the AC units working, I got my wish. It’s somehow good to know that nothing about a DSL line depends on local power working.

Test successful.

If you don’t have your cable/DSL modem an router on a UPS, maybe now is time to consider it? -m

Tuesday, May 6th, 2008

Maker Faire photoset

Up on Flickr. Anita and I had a blast. We spent about 8 hours and saw maybe half of everything. -m

Sunday, May 4th, 2008

Weekend Project: save $75/month with Ooma

New gear, an Ooma VOIP box. I plan to post more technical details soon, but the short story is that you get a sleek little box that goes between your dsl or cable modem and your router, and you get unlimited local and long distance calling. For free. For life (or 3 years, according to the TOS). Check out the Flickr set of the unboxing experience.

WIth this, I plan to turn off my landline, to the tune of about $35 a month, and by not using our mobile phones for so much long distance, reduce the calling plan for another $40 a month. The one-time cost for the box set me back about $231, so I will be even in just over 3 months. (Only recently, these things were retailing for $599.)

How do these guys stay in business? I’ll write more about this too, but the short story is that bandwidth is really, really cheap, monopolistic efforts of telecom companies notwithstanding.

So far I’m really happy with it. The online Ooma Lounge isn’t as good as Vonage’s system–for one thing, you can only see voicemails, not any kind of call logs. But the features that are there Just Work. The documentation is short and simple but thorough. Setup was a breeze.

Have you tried Ooma? Comment below. -m

Friday, April 11th, 2008

Google App Engine dwarfed

Thanks to chromatic for the link. Largely hidden,  largest app clusters of this particular platform can:

Control over a million computers and can deliver over a hundred billion advertisements per day.

However, “don’t be evil” is not a part of this particular platform’s strategy… -m

Thursday, March 20th, 2008

Geeking out

I have here a pre-release copy of Cory Doctorow’s novel Little Brother.

With permission.

In plain text.

Being read with the UNIX command less.

On an XO laptop.

And so far it’s awesome. -m

Friday, February 22nd, 2008

Hands-on Kindle

Amazon hosted a networking event tonight. They had me at free beer and a chance to look at a Kindle. Now that I’ve actually played with one, I can comment on some of its features for better or worse.

It’s heavier and more solid than it looks. With the little padded cover, it could pass for a physical book in most situations, and it would probably survive a drop to the floor just fine.

The screen does look great, even in the sub-optimal lighting conditions of a bar. I had to compare with the XO when I got home, and with the backlight off, I think the resoloutions are very nearly similar. However, the XO (without backlight) is fairly hard to read at indoor lighting levels, though in full sunshine it’s great. I don’t know how easy it would be to read the Kindle in full sunlight…

Page turning is annoyingly slow, and annoyingly easy to do by accident. The annoying part is that after pressing the button, nothing seems to happen for a second, then the page blacks out, waits another second, then displays the new content. I understand the technical limitations of the black flash (and the corresponding benefits–essentially zero power consumption to hold an image). But it feels like if it started working as soon as the button was pressed, it could cut the overall page change time in half. Keyboard entry felt slow and lagged as well.

Overall, the device didn’t feel usable to me. I somehow stumbled my way into Wikipedia and got to see the browser in action. I would love to see a touch-screen version.

Did seeing one change my mind about buying one? Nope. Still waiting. I’d buy this one at half it’s current price, an updated model for maybe more. -m

Tuesday, January 15th, 2008

OK, I have to ask…

Does the MacBook Air make a good ebook reader? -m

Monday, December 24th, 2007

OLPC is here

I’m taking some time off from work to relax a bit. And just in time for that, my OLPC arrived. Check out the photoset on Flickr. It’s an impressive little machine, and I’m very happy to have got this instead of a Kindle. :)


Tuesday, November 27th, 2007

Amazon’s most valuable IP

Or, why the Kindle cost $399 at launch.

What is Amazon’s most valuable IP?

How about a list of registered users who are guaranteed as willing to pay a premium price for a nifty gadget (I mean “service”) along with the exclusive privilege of buying more things from Amazon? Somewhere in Amazon’s database land, alongside all the details and purchasing history they already have for each customer, there’s a single bit called something like owns_kindle. Those bearing this mark are the ur-early-adopters, the loyalists, the customers with a vary large net future value. The marketers dream. Opt-in isn’t even an issue–what Kindle owner won’t be interested in special offers and exclusive deals for their special device? Where else are they going to go?

That one bit alone is probably worth another $400, making it the most valuable IP in terms of dollars-per-byte that Amazon holds. Even if they do a drastic price cut soon (and such price cuts will at some point be inevitable to sustain the market), even if they refund half of the difference to the early adopters, they will come away with super-sized smiles. -m

P.S. s/Kindle/iPhone/ and s/Amazon/Apple/ and this entire post still holds.

P.P.S. There is a pretty good play Apple could make here around an ebook reader. Tie it to the same wireless service plan that the iPhone uses, make books available through the iTunes store (including tons of Gutenberg/public domain content/creative commons for free), and put it on a very slick designed piece of hardware. But even in this case, it will initially sell for a premium price for the reasons above. Game on!

Monday, November 19th, 2007

Kindle my disappointment

Where’s Project Gutenberg? One difficulty in launching an ebook platform is the lack of available titles. I keep hearing about 80,000+ titles, but expressed as a percentage of Amazon’s book catalog, it’s minuscule. There should be all kind of public domain titles ready to go on day one. And where’s the Creative Commons books?
There’s some public domain books to be found, but none are free. Take, for example, A Connecticut Yankee in King Arthur’s Court, a book (in paper form) sitting just out of arm’s reach as I write this, waiting to be read. If I had it on a device, particularly one with a good screen, I’d be more inclined to keep it, and dozens others, on hand in my backback and be ready to read at a moment’s notice. But no.

The problem is the the “we take care of the wireless delivery” part, called Whispernet(tm). It’s not really free, nor bundled in the service price. It’s bundled in to the cost of every media access. Is it fair to pay $9.99 for a New York Times bestseller? Sure. But it sucks to pay $1 for an A-list blog that’s free everywhere else, or to get literally nickeled and dimed for the privelege of “converting” and delivering your own content to your own device.

By the way, who gets the money paid for accessing, say, a CreativeCommons non-commercial licensed blog via the Kindle? Somebody should look into that.

I applaud Amazon for pushing to innovate in a space that badly needs it, but the financial model behind the wireless access encourages the wrong kind of things. Exceptions, like unlimited Wikipedia access (be still my heart!) still need to be hand approved by the gatekeeper. Information wants to be free, it doesn’t want to be a service, though that’s hard to see when the dollar signs get in your eyes.

Many folks are comparing this to the original iPod launch–remember, the huge klunky one with a tiny capacity, black and white screen, and a mechanical click-wheel? There’s some strong points of similarity, but stronger differences. For one, anyone with an iPod can easily rip their existing CDs, not to mention obtain MP3s from other methods (so I hear). There’s nothing like that yet for books.
Where’s the documentation for the new, proprietary ebook format? I don’t care about the DRM crap. I care about being able to create new content, or repackage existing content for which I have the rights, and for that, I’m having trouble coming up with a rationale for an entire new format. I would love to do some cool things with this platform. Perhaps I will some day, though my enthusiasm is somewhat lessened by the difficulties I would face getting anything cool onto the devices. -m

Monday, November 19th, 2007

Kindle as a writing tool?

Amazon announced their ebook reader today, Kindle. Some of the earlier hype I’d read about it suggested that it would be not only a reading tool, but a writing tool as well.


The obvious thing is the keyboard, an immediate non-starter for typing more than a few words. But if an external keyboard is possible, I could still live with it. For now, it seems like an OLPC would better serve my needs for an ultra-portable writing station. And for the same price, I get one and so does somebody else who need it. -m

Sunday, August 5th, 2007

The planetary air conditioner

If a free energy device (like this one) were really possible, simple economics would dictate that (as soon as patents expired, etc.) one or several would be found in every cell phone, iPod, notebook computer, desktop computer, appliance, automobile, airplane, house, building, and factory. That’s a lot of waste heat that would get dumped onto the planet’s surface, maybe even worse than burning-stuff-to-produce-greenhouse-gasses.

But if you have unlimited energy, it would be straightforward engineering to produce a large scale air cooling unit that would (beam|radiate|dissipate) heat into space. In effect, a planetary-scale air conditioner.

Remember when you were younger and you left a window open with the A/C on, and somebody said ‘what are you trying to do, cool off the whole outdoors?’ Finally an answer to that question. :)
November, National Novel Writing Month, is coming up. Could this be the kernel of a story? What other practical considerations would there be around free energy? Comment below.


Friday, June 22nd, 2007

Get yer Go

Still more mobile news. Yahoo! Go is shipping. No alpha, beta, gamma, etc.–the real deal. Give it a whirl. If your phone, like mine, can’t handle the awesomeness, you can visit the slick web-only version at -m

Wednesday, June 13th, 2007

Poor-Man’s Apple TV: Your Old iPod

I have an older iPod. I don’t go G numbers, but it’s 40 gigs and a black and white screen. The battery life is measured in minutes. Hmm, 40 gigs, same as the original Apple TV.

We don’t have a TV in the place, but we do watch movies on the computer screen. As long as you’re willing to plug in what’s essentially a portable hard drive, you can watch movies on any screen with a nearby FireWire port. Battery life isn’t an issue because the only time you use the iPod, it’s plugged in.

What do you do with your old iPod? -m

Sunday, December 31st, 2006

What I did on winter break

For the last several years, I’ve taken some time off around the end of the year to work on a special project. In 2004 I ported some of Rick Jelliffe’s code from Java to Python. In 2005, I made an editing pass over a novel I wrote the previous November during NaNoWriMo. This year was a little different. I:

  • Worked. Enough stuff is going on with the day job that I couldn’t take a full week off.
  • Got sick.
  • Caught up on some homebrewing. Reorganized my brewery.
  • Wrote. More stuff coming soon on
  • Pimped a babyswing. (photoset)
  • Started reviewing WWW2007 and XTech papers.
  • Started taking a video MIT class on differential equations. (If you have OS X 10.4+, fire up Grapher and try y’=cos xy, y(0)={-5,-4.5…5})


Tuesday, October 24th, 2006

Opera Mini for Treo

Opera just released a version of their Mini browser for Treo. Here’s what the download and install process looks like.

  • point your existing Blazer browser at
  • the page detects your device (a Treo 650 in this case) and offers a download link
  • clicking the link starts a 100k download
  • the phone offers to store the download in the “applications” area
  • hunt through the ultra-confusing menu system that Palm has inflicted on users. Categories are “All”, “Games”, “Good”, “Main”, “Multimedia”, “System”, “Utilities”, Wireless Apps”, and “Unfiled”.
  • finally I find it under “Unfiled”. Click.
  • Error message “Missing IBM Java VM”: “Please ensure that IBM’s WebSphere Micro Environment Java WM is installed.”

In summary: Opera is great software, judging by the glowing reports all over the web. But installing mobile apps is a major pain spot. See also Daniel Raffel’s take on the confusing state of mobile development.

Hard to develop. Hard to install. We need to fix this asap. -m

Tuesday, October 3rd, 2006

Mobile data at risk?

The little one just turned a month old. Since I have a spare moment, time for some blog catch-up. A C|Net puff piece survey reports

More than two-thirds of respondents said that their data was most vulnerable on laptop PCs, while 40% chose “other mobile devices” (i.e. PDAs, mobile phones, wireless devices)

Mind you, this is just a survey of how repondents felt, not reporting any specific security issues.

Is data accessible through mobile devices at risk? Absolutely. What are you doing to secure your data? -m

Tuesday, September 26th, 2006

XHTML Print is final

Another example of a small, useful spec defined in a language humans can actually read and understand. It also seems incredibly useful to be able to print basic things without going through the multi-megabyte printer driver madness that everyone else seems to be going for. -m