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  1. CircutScoper

    Replacing tiny IR LED

    Aha! The legendary Dark Emitting diode (DED) of story and fable?
  2. CircutScoper

    Temporary Delay Circuit

    ...all gates were tied to either a ground or 5V source... Only inputs or output pins too? If the latter, then you have a perfect explanation for overheating!!
  3. CircutScoper

    Replacing tiny IR LED

    Hey Mighty Casey! Your problem sounds like (a) bad solder joint(s), of which I have had the "joy" of chasing more than a few -- only some of which were *ahem* of my own creation. A favorite spot for them to hide is where battery contacts connect with the circuit board. Lots of mechanical...
  4. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    It was a question of voltage and efficiency. Not current. >80% of the voltage, and therefore power, of your 15V supply was being wasted in the ballast resistor. By contrast "only" 50% of the power of your 5V PS is going down the drain. You tripled your circuit's efficiency.
  5. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    I don't understand your question about "max current." Sounds like something to consult the LED datasheet about -- not the PS's.
  6. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Then running them from a 5V supply with 180 Ohm resistors would save 2/3rds of the energy and 80% of the wasted heat (assuming equal power supply efficiencies).
  7. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Even more efficient would be a 6V supply.
  8. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    If you mean my edits, I apologize. I mis-read the way Mr. 101 labeled his LED voltages.
  9. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Why not connect all your LEDs in a single series string and power them all from a single resistor, thus drawing only half the current? Sketch attached. By the way, the photo is of a beautiful red shouldered hawk that kindly paid me a visit one day outside my office window -- not an owl.
  10. CircutScoper

    what's this part?

    Tunable (note the adjustable chokes) LC audio sideband filter out of a (very old) SSBSC transceiver?
  11. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Maybe a picture will help. What is the voltage across the resistor? Hint: You'll never know until you measure it with an actual voltmeter.
  12. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Well, be fair. Imagine trying to explain that question to an English Lit. major (which, for all we know, is actually the OP's background). What's in play here is basic EEngineerish.
  13. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Yeah. But what's also missing is a OP who understands the question: What's the voltage across the resistor?
  14. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Then to repeat the question that has already been repeatedly asked, what voltage is dropped across said resistor?
  15. CircutScoper

    Buzzer Circuit

    coaxing high-energy ions from our ancient tandem particle accelerator Would that have been a tandem Van de Graaff? Many decades ago when an undergrad at CalTech, I designed and built beam-chopping circuitry for one under the Sloan/Bridge labs. It was used (IIRC) because of its ability to...
  16. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Really? Then I strongly suggest you be VERY careful while you work on it! Because: If the designer of your "setup" was really willing to waste 15V across what's nothing but a heat-producing ballast resistor, then the total supply voltage across resistor plus series LED chain can be expected...
  17. CircutScoper

    2 latching relays, 2 pushbuttons, 2 dc 5 Volt motors and 4 limit switches

    Congratulations on getting your circuits to work. As for reducing the speed of one of the motors, you might consider a simpler solution as illustrated by D1 and D2 in the diagram below. If one diode pair didn't slow it enough, you can of course add more.
  18. CircutScoper

    Detection of electronic device

    Proper shielding is key.
  19. CircutScoper

    Difficulty finding the appropriate resistor with power calculation

    Yours is so important a point that it merits repeating (in boldface): The voltage that counts for the resistor power rating calculation (P = V^2 / R) isn't the supply voltage, but is instead the voltage measured across the resistor.
  20. CircutScoper

    Detection of electronic device

    Very painful, too -- if you're a bug.
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