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  1. hevans1944

    Hall effect switching info needed

    What, exactly, is "an electro-mechanical aero engine?" Is this an internal combustion engine (ICE), running on petrol, that is used to spin the propeller of an aircraft? Is it a full-sized engine intended for manned flight, or a smaller, model, engine? Why do you want to use eighteen cylinders...
  2. hevans1944

    Please help identify this variable resistor

    Since it came out of a record player, I would bet dollars to donuts that it is an audio taper instead of a linear taper potentiometer. Try this one on for size.
  3. hevans1944

    I just thought I'd measure a few diodes V vs I

    The forward and reverse characteristics match each other at very low voltages. After all, the diodes characteristic curves are continuous through the origin (zero volts, zero current), and until the depletion zone width is maximized by reverse voltage biasing, or minimized by forward voltage...
  4. hevans1944

    Need help... Dielectric Grease used in contacts

    Please contact this company in Ontario, Canada, for information on their patented Stabilant and Stabilant 22 product. Or explore this website link. Their product becomes conductive under the influence of an electrical field between contacts but is otherwise non-conductive. Dielectric lubricants...
  5. hevans1944

    Mystery Wiring, Need Help.

    If you purchased this online, a link to the vendor's website could be helpful. And maybe a model number for the motor. It's probably of Chinese manufacture, so never mind trying to find out who made it. As a footnote, most "Universal" motors use a series-connected field winding, sometimes two...
  6. hevans1944

    Mystery Wiring, Need Help.

    I would try either one of Ed's connection diagrams. To change motor direction, reverse the connections to B1 and B2.
  7. hevans1944

    Press a button to start a timer project? Thanks.

    Wow! Calculators are less than five bux just about anywhere. This solution combines the counter, decoder, and display (usually the most expensive components of a project like this) all-in-one with just the addition of an FET to operate the "equals" key. Please let us know how that works out for...
  8. hevans1944

    Mystery Wiring, Need Help.

    It's a Universal AC/DC motor.(see post #1).
  9. hevans1944

    Serial communication problem.

    The relationship between TTL voltage levels for logic levels of "zero" and "one" and RS232 voltage levels for idle (mark) <-3 V and high (space) >+3 V is what it is. So, yes, disregarding the magnitude of the TTL versus RS-232 signals, the polarity is inverted. So what? You process the TTL...
  10. hevans1944

    UPS battery

    You DO NOT check, add, or fill sealed lead-acid batteries with distilled water. That is why they are sealed.
  11. hevans1944

    Looking for a specific transformer

    Yes, it is. Come back here often with any questions or problems that come up, and please upload pictures of your progress.
  12. hevans1944

    Looking for a specific transformer

    It sounds to me (so far) that @Electric-T doesn't have any design specifications. Why does he really want 15 VAC (post #22)? Battery chargers require DC of course. How can you possibly find a vendor without specifying the transformer you "need" and how did you determine what you "need"? In post...
  13. hevans1944

    LED or CFL flickering with motion sensor in circuit

    It made me nervous too, but I left it installed. This was for dimming eight (four on each side of the medicine cabinet mirror, Hollywood dressing room style), large-globe, frosted, 60 W incandescent lights. Worked pretty good for that, and at full brightness the lamps kept the bathroom nice and...
  14. hevans1944

    LED or CFL flickering with motion sensor in circuit

    Well, I did say might... but you are right. It was a dumb suggestion to try to fit the lamp inside the handy-box. Shouldn't put anything in a handy-box that is going to intentionally generate heat. It might even be illegal to do so, in which case it was a really dumb suggestion, although I have...
  15. hevans1944

    Building an electronic foil surf board

    I think we who have responded so far can all agree that @billy bob surfer guy is in waaay over his head when it comes to building a powered hydrofoil surfboard. If you look at some of the documentary videos produced by Liftfoil and visit their blog you can begin to see some of the problems they...
  16. hevans1944

    Building an electronic foil surf board

    I cannot intelligently argue this point because the physics is beyond my capabilities. However, the one kilowatt three-phase brushless motor I suggested the OP try out is rated for 25 kgf thrust at 4500 rpm, more or less linearly decaying to 15 kgf thrust at 1 m/s, according the thrust graph...
  17. hevans1944

    Building an electronic foil surf board

    It is rather large, but appropriate for this application. You need a LOT of power to plow through the water at 25 mph, even with a low-drag wing and a low-drag mast to lift the surfboard out of the water. These sealed, underwater motors with integral ducted fan appear to have been originally...
  18. hevans1944

    Building an electronic foil surf board

    The motor-driven hydrofoil attached to the bottom of a surfboard and powered by a battery in the surfboard is a fantastic idea that should be very successful both as a commercial product (if you can spare $12,000) and as a hobbyist project. Think jet skis that you can stand up on, but electric...
  19. hevans1944

    Serial communication problem.

    Yep, but with emphasis today on had. There are so many ways to implement serial comm links today, including the ubiquitous USB, that personal computer makers no longer provide either DB-9 or DB-25 serial ports. And of course the so-called Centronix DB-25 "parallel printer port" (which I actually...
  20. hevans1944

    Serial communication problem.

    TTL (and, earlier, DTL) used so-called "totem pole" outputs that could either source a small current (for logic 1 level) or sink a somewhat larger current (for logic 0 level). That means any given output was either driven high toward Vcc or driven low toward ground or logic common. If you...
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