Member Since: June 20, 2010

Country: Canada

  • Holy imaging, Batman! I remember working on a FLIR system that needed liquid nitrogen for cooling. Later on, I worked on a FLIR system that didn't need cryogenics. It was so small that one person could carry it. (Not far, but even so....) The unit cost was well below $100,000.

    Now I see this! It's more than I want to spend (correction: more than I can get away with spending), but I could scrape up the cash to build a FLIR system for myself. Wow!

    <End rambling old engineer mode>

  • It's not as important to never make a mistake as to own up to a mistake and fix as quickly as you can. Good work. Sparkfun.

  • Why is it that the perfect gizmo comes out just after I place an order? Coincidence? Hah! It's a conspiracy, I tell you! :-)

  • Back when I was in university (electrical engineering), I took an electrical machinery course. Working with power transformers and big induction motors can be dangerous, so we got a few pointers from electricians.

    1) When you're working with high power gear, turn it off and lock the switch. 2) If you can't make Rule #1 happen, put one hand in your pocket. Seriously. That way, if you do bridge a pair of high voltage contacts, the current is through one hand. It might destroy your hand, but you'll be alive --- probably. 3) If you can't make Rule #1 happen, assume all lines are live. If you need to touch a line that could be live (i.e. any of 'em), tap it with the back of your hand. That way, if it's live, the spasm will pull your hand away instead of locking it to the live line.

    And then there's my own addendum: The question isn't: "Am I being paranoid?" The question is: "Am I being paranoid enough?"

    Of course, this doesn't cover it. Not by a long shot. But there is an underlying theme: be very, very careful, and learn everything you can. If you get a chance to learn from tradespeople who work with wiring and live circuits for a living, do it.

  • A blast from the past indeed! In 1979, I cobbled a flash ADC from an LM3914. It wasn't a great ADC, but it worked well enough for my 4th year engineering project. Besides, I could actually afford to buy one! I had no idea these parts were still in production.

  • OSHW is one of the greatest things I've seen in many years. It encourages innovation while giving credit to the folks who've brought a design to its current state.

    Yes, there are people who've tried to buy a legitimate product and gotten counterfeit junk instead. There are many more who'll happily buy ripped off stuff and brag about the money they saved, and still more who just don't want to know why their new Widget 2.0 costs so little.

    There are two things I think we all ought to do: 1) Buy things from reputable vendors and pay fair prices. 2) Tell people around us what we do and why we do it.

  • Oh crud! I did say signal lines, didn't I? Remind me to never type without my brain engaged.

    Power lines! Not signal lines! (Except for specialized signal conditioning applications.)

    I do understand the principles, and my apologies for not checking my post before hitting submit.

  • Well, Wasted, I've got to applaud your succinctness!

    Analog side design for ADCs and DACs gets tricky. Component layout and PCB trace routing are very important. For 8 to 10 bits at low data rates, you can get away with using broad guidelines, which are usually described in the datasheets. As your bit count and data rate increase, the design gets more critical, and you're well advised to get a skilled layout specialist involved.

    In general, keep the analog and digital sides separate. Avoid having digital traces cross analog traces. If you can, use multilayer boards and use ground planes to isolate analog and digital sections. Use the smallest bit count and lowest data rate you can get away with.

  • The basic concept is that capacitors pass high frequency signals and block low frequency signals. For digital circuits, the usual intent is noise reduction. If you put a capacitor between a power line and ground, high-frequency signals -- and most noise is relatively high-frequency -- have a low-impedance path to ground.

    Determining the precise value of capacitance would require knowing the frequencies you want to keep, the frequencies you want to reject, impedance, and no doubt a few things I've long since forgotten. But fear not! Most noise-decoupling capacitor values are chosen by rules of thumb and experimentation. Most IC vendors have done the experimenting for you, so your best resources are datasheets and application notes.

    The old standby for digital ICs was a 0.1 uF ceramic capacitor across Vcc and ground, but that rule of thumb has evolved over the last 20-odd years. (Editted for clarification and to remove brain-dead carelessness.)

  • Since I'm not an American citizen, I'm not sure what -- if anything -- I could do to help. It does bother me, though, that this legislation could have such a world-wide impact.

    I applaud your decision to keep your website up. While I understand the thinking behind the outfits that blacked out their sites, it seems to me that they're hurting their supporters more than dissuading legislators.

    Ultimately, there's only one good way to stop software piracy: don't buy stolen goods. Thieves can't prosper if nobody does business with them.

No public wish lists :(