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  1. BobK

    how to prevent simple AA battery electromagnet short circuit/overheating

    You make it safe by determining the maximum safe current from the battery, determining the resistance that will result in that current, then making the wire long enough to have that resistance. For an AA cell, that is about 1A at which the battery will last about 1 hour. To get 1A you need a...
  2. BobK

    Basic Soldering advice

    Hopefully, you know that you heat the parts to be soldered and melt the solder on the parts, not on the soldering iron. Bob
  3. BobK

    Electromagnet project

    You can do the same thing with only 2 coils. In fact, it is in common usage and is called a stepper motor. Bob
  4. BobK

    12 v to 48 v boost converter for 48 v electric bike

    OK. That makes sense. To get the same run time, though, you should go to a 12V 100AH battery. Bob
  5. BobK

    12 v to 48 v boost converter for 48 v electric bike

    What do you expect to gain by going from a 48V to a 12V battery? Because you will be losing about 20% in the conversion. Bob
  6. BobK

    Which gas solder

    No. You put solder paste on the pads, place the part, then use hot air to melt the solder. Bob
  7. BobK

    How to trigger solenoid with very low current?

    You are expecting 5 to 20 mA through the skin? Think again. 10 mA would be a painful shock. But don't worry too much, with 9V you would be lucky to get 10 μA, which is nowhere near enoufh to trigger a relay. You need a touch sensitve switch circuit to do what you are trying to do. Bob
  8. BobK

    Which gas solder

    These chips are designed for reflow soldering. If all of the connections are out the outer edges you might be able to solder it by using soldering paste on the pads and using a hot air station. Another option is an electric frying pan. Look for videos on YouTube. Bob
  9. BobK

    Looking for off the shelf wave generator with low internal impedance

    I dont think you will find that in a single instrument. And, if you do, it would likely break your budget. Bob
  10. BobK

    Connect a circuit to already existing system

    With wires. Bob
  11. BobK

    dimming LED indicator lights

    Connect the output of the PWM to the line labelled PWM on the schematic in post #6. Bob
  12. BobK

    Where there's smoke...

    In electronics we do not use pictures, we use schematics. Here: Bob
  13. BobK

    dimming LED indicator lights

    The PWM controller, which we have not yet discussed, will require a supply voltage as well. 12V would be a good one since that is available. Bob
  14. BobK

    IRF5305S Power MOSFET, is switching voltages of 3V possible?

    You may notice that the board is speced to switch a minimum of 5V. It will not likely work at 3.3V. The threshold voltage is listed at min 2 and max 4V. That is the voltage that allows 250uA to pass. So it is possible that it will not even allow 250uA of current at 3V let alone 2A. Bob
  15. BobK

    RGB LED strip

    Simply connecting an RBG strip to a speaker would cause great distortion on the speaker. You need at least a transistor and resistor in between. Look up some circuits on the web. Bob
  16. BobK

    IGBT current limit

    How much voltage are you driving the coil with? From that, and the equation below you can determine the on time necessary to give you 4A. dI /dt = V / L Say for instance, that the voltage is 12V. dI / dt = 12 / 0.00158 = 7594A / sec So you would want to leave it on for 4 / 7594 = 526uSec. Bob
  17. BobK

    How does a GPS receiver/transmitter (transceiver) work on a circuit board?

    An Arduino is a microcontroller plus a lot of other stuff. Microcontroller chips can be as small as a couple of mm square. Bob
  18. BobK

    Where there's smoke...

    No, between the ring and the LED. Your picture shows the resistors breaking up the ring. Bob
  19. BobK

    Where there's smoke...

    Nope, the resistors go between the ring carrying power and the LED devices. One for each LED on either of the two contacts. Bob
  20. BobK

    dimming LED indicator lights

    Nothing changes on the switch side. We are just interrupting the ground connection for all the LEDs. Bob
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