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  1. BobK

    Wireless sign

    Look on Ebay for "wireless remote control". These are inexpensive and will do the wireless part of what you need. Are you capable of hooking up the power source, the lights and the relay that is the output from the wireless receiver? We can help with that, but you need to answer Harald's...
  2. BobK

    Wireless sign

    The push button does what? Turns a lighted sign on and off? That is fairly simple and could be done by a using a repurposed wireless doorbell. Bob
  3. BobK

    Design of isolated buck converter

    And the answer, is "not very well." Bob
  4. BobK

    Question about DC and Coils and LED.

    Well, you are learning something :) Look up transformer. Hint, they do not work on DC, which is what you are trying to do. Bob
  5. BobK

    Question about DC and Coils and LED.

    If a static magnetic field would light up an LED, you could just put a permanent magnet next to it and free light forever. Bob
  6. BobK

    Question about DC and Coils and LED.

    Not to mention another coil to pick it up and send it to the LED. Bob
  7. BobK

    Linear amplification for kids robo project

    A properly designed op amp circuit will be as accurate as the resistors you use. If you need an analog signal out, then it will be better and fare simpler than and ADC / DAC combination. Bob
  8. BobK

    Question about DC and Coils and LED.

    Agree with Steve. I believe the OP had the (wrong) idea that putting an LED near a magnetic field will cause it to light up. Depending on the diameter and length of the wire, I am surprised that he did not see heating of the coil or the battery. Bob
  9. BobK

    special oscillator

    It is that humorous, everyone knows that it takes 100 10K resistors to make a variable tone generator. Bob
  10. BobK

    78l33 circuit regulator, thought it would drop a 5v voltage to 3.3 v but no!

    It will definitely not work on 3.7V input. You need about 2V above the output. Look for a low dropout regulator, which allows a smaller difference between input and output. Bob
  11. BobK

    Current question

    That was not helpful. Bob
  12. BobK

    Limit car battery current

    Ohms law will tell you what resistor would draw 41A if placed across a 12V source that is capable of that current. This is not very useful. Tell us what you are trying to do. Bob
  13. BobK

    Buck-Boost Inverting Power Supply

    So why do you need a buck / boost converter to get 12V? Bob
  14. BobK

    Linear amplification for kids robo project

    The NE5532 is designed to operate with ±15V. It's output can only go to within 2-3V of the power rails, so it will not work they way you are trying to use it. You either need to use dual supplies, or switch to an op amp designed to operate on a single power supply with rail-to-rail inputs and...
  15. BobK

    Solder terminal to breadboard

    Just use one of the jumper wires from your breadboard. Bob
  16. BobK

    Linear amplification for kids robo project

    Show us the circuit. A simple op amp circuit should work fine. Bob
  17. BobK

    Why I prefer electronics to plumbing

    I did post it a while back: https://www.electronicspoint.com/threads/function-generators-role-and-effect.276123/#post-1669844 The contest was at our dance studio. We also went to a bar just before, and lo and behold, one of the waitresses was dressed as Friday. The bartender told her "Your...
  18. BobK

    I had a thought... (Vreg close to Vin)

    Well, it is difficult to deal with controlling the voltage with electronics running directly off the battery since the measured voltage will be out of range of an opamp or comparator. Bob
  19. BobK

    I had a thought... (Vreg close to Vin)

    The basic topology for a buck / boost converter already does produce a negative voltage. https://en.wikipedia.org/wiki/Buck%E2%80%93boost_converter Bob
  20. BobK

    Measuring the speed of a Frisbee & Boomerang

    Okay, that makes sense. Bob
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