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  1. hevans1944

    Free Energy / Energy Harvesters / Perpetual Motion

    What, pay for bottled water and bottled air? Go read Heinlein's The Moon Is A Harsh Mistress to get some idea of where this makes a whole lot of sense. I wonder how much a sip of water or a breath of air costs for the crew on the International Space Station?
  2. hevans1944

    Winding coils

    The OP may not have access to a digital camera, or maybe is too embarrassed to show us a picture...:eek:
  3. hevans1944

    Help with 3v relay

    Easy enough to check that too: measure the coil continuity using the diode scale. Should read about 0.7 volts, the forward drop across a silicon diode in one direction, the actual coil resistance or about 25 ohms in the other direction. If you get the same resistance in both directions, double...
  4. hevans1944

    Reactance Question

    No it is NOT a resistance value. And for capacitors, your multimeter will indicate an open circuit (eventually) as the DC voltage supplied by the multimeter charges the capacitor. The multimeter may measure (probably will measure) a resistance for an inductor, but this is also NOT the reactance...
  5. hevans1944

    Greetings from the Crystal Wizard!

    Welcome to Electronics Point @Crystal Wizard. And welcome back to the electronics game. The basics have not changed, just the technology used to implement solutions. And there are NO stupid questions, just stupid answers (sometimes). Ask away and someone here will try to light the way. Hop
  6. hevans1944

    Help with 3v relay

    Sure sounds like the relay is actuating, so the problem must be in the contacts. Do what @Minder suggested: ditch the 24 V power supply and just perform continuity and resistance checks with your multimeter. Use all possible combinations of the relay pins (except the two pins connected to the...
  7. hevans1944

    Winding coils

    Plenty of picture here. Or go to this Google page.
  8. hevans1944

    Musicians Helper

    For as long as I can remember, there has been a publishing service, Sams Photofact, that sells service manuals, schematics, etc. for almost every make and model of TV, radio, and phonograph available in the USA. Google that phrase and visit my link. Back when there were still Radio and TV Repair...
  9. hevans1944

    Help with 3v relay

    The relay you specified requires a whoppin' 120 mA to actuate. The coil resistance is only 25 Ω. Make sure your 3 V source can supply the required current. See @Externet's comment on post #2 which is spot-on.
  10. hevans1944

    wiring up relay with Arduino

    When you need to control an appliance with an Arduino output, a relay actuated by the Arduino is a good intermediate interface. The coil of the relay will typically be low-voltage DC rated at 5 V. The relay contacts will typically be either one Form A, single-pole, single-throw, normally-open...
  11. hevans1944

    Winding coils

    I think most folks use a kind of lathe, turning at a very slow speed, to assist in feeding the wire by hand onto the coil form. It is important to keep sufficient tension in the wire while winding the secondary and to avoid irregular spacing of the turns. A foot-operated switch for the lathe...
  12. hevans1944

    Musicians Helper

    Your biggest problem will be getting paid for your services. How well do you barter? Oh, and welcome to Electronics Point, @TJrhythm!
  13. hevans1944

    Electromagnet with strength controlled by photoresistor

    This sounds like a fun project! Welcome to Electronics Point, @purj. I am sure there will be many posts to this thread, some to help you and some to give you ideas. I will start off with a few ideas... There was a toy (Magna Doodle) I bought many years ago for my young children to express their...
  14. hevans1944

    Ultrasound Modules

    The HC SR04 is NOT designed for underwater use. For underwater ultrasonic transducers see this page and visit the links found there. Considerable signal conditioning is required for operation in the megahertz range. Instead of asking us for transducer recommendations, please tell us what you...
  15. hevans1944

    cake water fountain help

    See my response on your other (duplicate) post, repeated below. Please refrain from posting the same question or problem more than once. Short answer: the pump is an AC induction motor. It does not run on DC. Long answer: copied from your other post below. You have two choices: (1) Purchase a...
  16. hevans1944

    need of voltage and current

    Voltage is measured between two circuit nodes and is responsible for providing power to the load connected to those two nodes. In the case of a battery charger, the voltage must be higher than the open-circuit terminal voltage of the battery to re-charge the battery. Current is measured in...
  17. hevans1944

    Measuring Amps, Am I Reading This Right!?

    As Steve said and I agree ...... So what this does is essentially short-circuit the transformer secondary. The transformer probably doesn't provide enough current to blow the fuse in the Fluke 23, so (assuming you have the meter set to measure AC current) the reading you are getting is the...
  18. hevans1944

    Thermal Imaging Camera Recommendations?

    The problem with thermal imagers (Forward Looking Infra Red or FLIR cameras) is calibration. Without knowing the emissivity of what you are "measuring" the numbers are almost meaningless with regards to component surface temperature. And emissivity is a function of temperature too. However, if...
  19. hevans1944

    BOSCH reputable car battery manufacturer? then where are datasheets?

    Yeah, I hear you. And I remember carbon piles from the 1950s. Transistors are just smaller, more expensive, versions that don't tolerate heat as well. I think they are making transistors out of carbon nowadays... diamonds IIRC.
  20. hevans1944

    Thermal Imaging Camera Recommendations?

    Howsabout you look at this page? Prices from a few hundred to a few tens of thousands of dollars, depending on what you need. Good luck on meeting your measurement accuracy specification. Do you even know the emissivity of the components whose temperature you want to measure?
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