Member Since: January 8, 2009

Country: United States



Purveyor of fine ARM products and various very cool things.




Sigma Pi Sigma

Spoken Languages

English, Mandarin

Programming Languages

Forth, C, Assembler(65C02, 68HC11, PPC, ARM)




Embedded instrumentation. Detection of the weakest of signals of all sorts. Synthetic aperture RADAR/SONAR and interferometric radio astronomy. Algorithms for multi-beam and spotlight. Inventor of the Rotating Graviometer.



I share not with mere Earthlings!

  • I have something in mind using hard drive magnets. Maybe even the coil and bearing. You don’t need gain of a million with 24 bit ADCs so that is nice too. The integration method gives ground motion and calibration should not be too hard. Typical seismometers because of the forced harmonic oscillator, give displacement, velocity, or acceleration depending on frequency so it is all mixed together in a real event. Getting only displacement (ground motion) is a lot cooler.

    I’m not crazy about the big pipe and mass and cable home seismograph plans. There are much easier smaller ways to get better results.

    My plan is for horizontal mainly because you get more stuff and it is a lot easier to start with a long period, mechanically. Some of the more dramatic vertical wave types don’t travel through water or soft material worth a darn. Like Love waves which can not propagate in a homogeneous medium but have a lot of vertical. Ideally I think you should not even get P-waves on a vertical since they are horizontal and compression.

  • If you tried to find this device in a search, “geophone” will get a lot of info. I didn’t see the period mentioned.

    One thing. The piece of copper tubing for a damper is on the same axis as the sense coil and I wonder about the back EMF for the current in the tube (very high current) is coupling to the sense coil? Dampers of this sort are usually a flat plate. The alternative is a resistance across the sense coil and no other damping.

    Or, and this gets to be a block box approach for most people, no extra damping, measure the mechanical damping and period of the system, solve the 2nd order DEQ for ground motion, and numerically integrate continuously. This actually gets you the most useful data and with the least number of parts.

  • Found em. Dr. Google knew they were there even if the Home Depot guy didn’t. Nate, I saw some additional savings. These are packaged like light bulbs. No plastic blister and heavy cardboard. Also, lifetime is a projected 11,000 hours. The 18/20 year units are rated for 20,000 hours. So really, half price = half life or same $/hour. Bought a bag of them anyway. (I wonder what fails first? Hot LEDs?)

    More important, the more expensive longer lived units may produce a significant cost savings from reduction in the amount labor and work/home injuries from cutting bulb changes in half.

    Last time I taught high school math, there was a section on linear programming (basic algebra/pre-algebra). If people actually learned this stuff, every high school grad could draw a linear programming graph and find the optimum.

  • Very nice. In Western Washington the $2.50 one is not in the stores. In fact, the twin pack for under $10 is 40W.

    For $2.50 I would have bought a bunch. I have a case of HP blade PSU’s that are nice and efficient and output 12V at 75A (100 amps with 220V input). I was thinking about tearing the lights apart and making a rail to light a long work bench. An old jumper cable is about the right gauge I think. The only drawback is that if you load these PSU’s high enough to get efficient, the tiny cooling fan screams like a banshee.

  • It is all very very interesting. I would like to see an analysis of the tradeoffs between development cost, sales margins, and viability of Open Source. Some linear programming with simple models is a good place to start. Anyone looking into this? I have no problem with OSH on 2 layer boards. 6 or 8 layer with lots of features and circuitry and testing and software dev time? Not so sure I want to give that away until some costs are earned back. Is there a proposal for something like “OSH starting 18 months after first release”?

  • When I was a kid we wore boxes for shoes! Phooey!

    Hearing all these comments as if said by Zoidberg I am!

  • I don’t see any test gear. A bench power supply and a soldering station, yes. Meters and scopes, no. Today you can do all that with a USB dongle for your laptop I suppose. Oh. That gave me an idea….hmmm. Might be a new project.

    Anyway, are you planning to describe a project process? Like do you keep everything in a GIT repo? Schematics, data sheets, code, drawings, parts spreadsheets, log-blog, photos? Can you do a paperless project and keep going if your laptop is stolen or spontaneously combusts? Curious people want to know!

    By the way, when you have money to burn, a Stanley-Vidmar cabinet will average a 3 to 1 space savings over shelves and bins. I love them but even very well used they are out of reach for home.

  • Blasted owls!

  • The REA killed the rapidly growing wind power industry. GE made a line of low voltage DC appliances and several companies made wind generators and battery control systems. One of them was so good that if parts are available, they are still being used in remote regions around the globe. The same kind of thinking killed all the electric trolley systems in the US except a few. There were lots of alternatives. It came to a screeching halt with subsidized vote buying - er - power distribution. Not that there is anything bad about that.

  • Just trust me. If you like your provider you can keep your provider. What could go wrong?

No public wish lists :(