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  1. BobK

    Trigger Try Me button with motion sensor

    kelley_eye told you how to do it, but apparently not in words you would understand. You need a PIR sensor with a relay output. This type of sensor will mechanically connect two wires when motion is sensed. He calls this no-volts contacts, though that is a term I have never heard before. So...
  2. BobK

    Audio amplifier recommendations

    You can get a tiny class D amp that is approximately that for about a buck on Ebay. Bob
  3. BobK

    Difference? Regular resistor and a current limiting resistor?

    Just like a travel agent might ask if you want a rental car. Bob
  4. BobK

    Difference? Regular resistor and a current limiting resistor?

    Just as a “rental car” is no different than a “car”, a “current limiting resistor” is simply referring to a particular usage of the resistor. Bob
  5. BobK

    Wiring mental block

    You would need a circuit that senses one of the multiple buttons, then simulates the number of presses the single button would take to select the desired pattern. Bob
  6. BobK

    Need to find a cheaper part than this: Micro USB charger board

    Look on Ebay or Ali-express. Bob
  7. BobK

    Arduino RGB strip controller switching problem.

    Never mind. I misinterpreted the schematic. These are the grounds of a common anode LED. No pullup required. Bob
  8. BobK

    Arduino RGB strip controller switching problem.

    There is nothing to make the R, G and B inputs of the strips high. Turning the MOSFETs on will make it low. Turning them off will do nothing. You need a pullup resistor on each output. Bob
  9. BobK

    PWM frequency generator for LED's

    You talk about 8 channels, and you want to control them via one knob (potentiometer). That is not 8 channels, that is one channel. A simple 555 circuit would suffice. Neither of the boards you referenced will dim then via one knob. The Adafruit board has a SPI interface which would need a...
  10. BobK

    LED buck drivers and reducing current

    Your driver is a constant current driver. Adding a resistor in series will not change the current. You could add one in parallel, but better would be to turn doen the current on the driver. Bob
  11. BobK

    NPN transistor still working? Strange ..

    Current cannot flow both into and out of the capacitor at the same time. Once the breakdown voltage is hit, the current is flowing out of the capacitor. This contnues until the current becomes too low to sustain the breakdown state, the transistor stops conductung and current starts flowing...
  12. BobK

    Dual charging

    The question you are asking is the least of your problems. A simple SPDT switch is all you need to switch from sending power from one type of battery to another. But, there is a lot more to this project than you realize. Lithium cells are actually easier than NiCd and NiMH to charge properly...
  13. BobK

    Need to drain off curent.

    And do remember, something has to heat up if you are slowing the elevator via generated voltage. (Just as it would with a mechanical brake) Bob
  14. BobK

    Rapidly change electro magnet polarity.

    You can change the polarity of the driving voltage quickly with an H-bridge, but the magnetic field will not change polarity fast because of the effect of inductance. Do you have the facility to measure the inductance of the your electromagnet? At 1 Henry with 1 Amp, it would take 200V to...
  15. BobK

    Pre amps or boosts

    Active filters can include gain, even adjustable gain. Bob
  16. BobK

    Bandpass filter help

    A solar panel is the wrong detector to use with a laser diode. You want a phototransistor. Or, better yet, you want device like the TSOP4838, which has the detector plus processing to recognize a specific frequency (38KHz for that part number) These are way better than what you would be likely...
  17. BobK

    Different Pass filters for different speakers.

    To do this right you would need to know the frequency tesponse and sesitivity of each of the drivers. Since they are random things you have lying around, that seems unlikely. Bob
  18. BobK

    Generac generator output

    Who said they were modern clocks? Bob
  19. BobK

    Reading value from Solar Panel Cell, current peak concern

    The whole positioning to be perpendicular to the direction of the sun thing sounds good, until you work out the details. A full 2-axis positioning system gives you about 30% more energy over the day than a fixed panel optimally positioned for the latitude. It is typically cheaper to buy 30%...
  20. BobK

    DC adapter in place of AC?

    Just because there is no electronics in the wall wart if it puts out AC. All the electronics can be inside the drill. Bob
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