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  1. hevans1944

    bridging ribbon wire

    Can you post a high-quality close-up photo of the problem? You might be able to replace the entire "painted on metal wire ribbon cable" with real ribbon cable. This comes with variable widths (number of individual wires) and lengths. Sometimes you can "harvest" short sections from discarded...
  2. hevans1944

    powerbank low power switch

    The Rpi doesn't draw much current. Perhaps you could use a MOSFET switch to apply power to it, using a comparator to determine when the battery terminal voltage is too low to turn on the MOSFET? A relay has some advantages if you want to turn it on when power is okay and let it drop out when the...
  3. hevans1944

    calculate number of turns and length for inductor

    It helps to obtain some practical experience measuring the inductance of manufactured inductors to obtain a "gut" feeling for inductance versus size of component, versus core material (if any), versus number of turns of wire. An inexpensive LCR meter will be an invaluable tool. Back in the day...
  4. hevans1944

    H-bridge over 6v dc engine

    You can purchase a commercial integrated circuit with H-bridges inside and all the details of how to keep them from "frying" are described in this example datasheet. Is there some compelling reason, other than self-education, why you are trying to build rather than buy this particular wheel?
  5. hevans1944

    Shorting a Battery

    It helps A LOT if you know what you are doing. Please tell us what you are trying to DO, not how you plan to do it. It sounds like you might be trying to wind a kanthal vaporizer coil to be powered from a rechargeable Li-Ion battery... a so-called box mod. Ever have one of those catch fire or...
  6. hevans1944

    running the hantek 1008c

    Setting the controls correctly will reveal the secrets of the Universe. Have faith, Grasshopper! Have fun too.
  7. hevans1944

    Variable Hertz

    In your previous thread (now closed) on this subject, you stated you would feed a low-voltage signal into a transformer and step that up to the 115 V AC required to operate the solenoid in the reed frequency meter. So far, so good. A 6.3 V center-tapped filament transformer with a 115 V AC...
  8. hevans1944

    Trouble understanding shunt resistance for short-circuit current measurement

    Thanks @TedA for taking a closer look. Lots of things wrong with the diagram, but you appear to have covered it. Sorry, @Neverthelessified, I wasn't paying close enough attention when I said, "Looks okay."
  9. hevans1944

    How does a 110v portable generator with brushes generate electricity?

    An AC generator or alternator energizes the rotor winding with DC, applied through a pair of slip-rings on the rotor connected to two spring-loaded stationary brushes mounted on the housing. One brush is insulated from the housing and the other is connected to the alternator frame. The rotor...
  10. hevans1944

    project of tracking module using 433MHz RF module

    I didn't want to bring up possible alternative technology. Anything that actually works (like the dual GPS) will be complicated and expensive. Since this is a college assigned "project" the budget is probably nil. One possible solution would be based on laser range-finding, except using the...
  11. hevans1944

    Trouble understanding shunt resistance for short-circuit current measurement

    Looks okay. Be sure to test the hardware and the software before carting it out to the field. Take along a few spares.
  12. hevans1944

    project of tracking module using 433MHz RF module

    This is not an appropriate transmitter/receiver pair for what you are trying to do. The transmitter input must be modulated with a low-frequency (200 to 3000 Hz) square wave that the receiver will interpret and respond with a similar square wave output. There is no provision in the receiver to...
  13. hevans1944

    Car park sensor --> need help with component functions

    Yes. And there are three reference voltages, all different, one for each comparator to compare against the signal from IC2a. Can you calculate what these three reference voltages are?
  14. hevans1944

    Trouble understanding shunt resistance for short-circuit current measurement

    Ted, I agree with most of your post. The OP must define his project in greater detail and specificity with regard to measurement accuracy and test protocol. At a former employer, we would spend months detailing every aspect of our field operation. This included contingency plans if something...
  15. hevans1944

    Measuring accurate low current which measurement hardware to buy

    You might want to look at this Mooshimeter wireless multi-meter if you have a cell phone handy. It also records to an SD memory card. I've been wanting to buy one. Maybe you can be my guinea pig and report back here on how well it works? Here is a link to some reviews of this spiffy new gadget...
  16. hevans1944

    Trouble understanding shunt resistance for short-circuit current measurement

    The Analog Devices AD623 series is a suitable commercial instrumentation amplifier. I would definitely use this integrated circuit. You can learn a lot trying to build the three op-amp version, but it is not easy to build one that works well. See discussion below. First, the two input op-amps...
  17. hevans1944

    Sending and receiving data cheap

    I attended a Texas Instrument seminar a few years ago where they were demonstrating their low-power wireless Bluetooth technology coupled with (what else?) a TI MSP430 microprocessor. All of us in attendance received a little coin-cell operated Bluetooth thingy with a temperature sensor. At the...
  18. hevans1944

    Solenoid energized indication

    If you REALLY want to know if the solenoid is energized, you need a Hall-effect sensor to detect the magnetic field created by the solenoid. However, somehow I think the LED wired in series with a resistor and this combination then wired across the solenoid terminals will do what @FoRs wants to do.
  19. hevans1944

    How To Make A Up And Down Mechanism Like A Grabbing Machine By A Single Push Button

    What exactly does that mean? What is a "kids room escape" and what does that have to do with retrieving an object using a magnet at the end of a crane? BTW, most keys are made of brass or aluminum and will NOT be attracted to a magnet. Please tell us what you are trying to DO.
  20. hevans1944

    Timelapse Electronics

    Sorry, but it is easy to blow components with software by improperly controlling I/O pins. I haven't seen a single line of code posted yet, and @Alec_t has already pointed out some wiring errors in his post #6. Also sounds like @neill is asking for a personal visit (for which he seems willing to...
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