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  1. BobK

    Simply Sunday afternoon project turned nightmare!

    True enough. If ypu are going to have to change the power bank every couple of days, might as well run the truck instead. Bon
  2. BobK

    what is the different between speaker wire and power wire

    Difference is 10 ga speaker wire is much more expensive, because it is a scam. Bob
  3. BobK

    Simply Sunday afternoon project turned nightmare!

    Have you veriftied this, or, at least, done a calculation to estimate it? If you drive your truck every day it is not likely to be a problem. If you go a week or more without driving, it probanly is. Bob
  4. BobK

    do parallel connected leds consume more power?

    To be more specific, if you need to run 3 LEDs, each with a forward voltage of 3V off a 12V supply, then putting them in series is more efficient then putting them in parallel. If you had a 3.7V supply, you could not run them in series but running them in parallel would actually be more...
  5. BobK

    how to harvest transformer

    That appears to be a switching power supply rather than a transformer. You could use it as is if you can use the output voltage(s) that it provides. Bob
  6. BobK

    Modifying a battery powered light to hardwired.

    If you connect it directly to a 12V supply, you won't have to worry about powering it any more, it will be dead. Bob
  7. BobK

    Microcontroller LED project.

    Sounds like supply voltage is too low. Green and blue require higher voltage than red. Check the voltage with the lights on. These are supposed to work at 5V, but I have used them sucessfully with one Lithium cell, about 3.7V. Bob
  8. BobK

    Just learning and confused what this resistor does

    Think of ot this way: the LDR is there to turn the light off, the resistpr is there to turn it on. Bob
  9. BobK

    Theory/reality mismatch in a transistor circuit

    The 1W rating of the zener is a maximim, it does not automatically use 1W. If it is 36.5 mA at 13V, the power is about a half a Watt. Bob
  10. BobK

    Where to get 4 pin to 2 pin 3.5mm adapter

    What are the four connections on the mic? Bob
  11. BobK

    16 x 2 alphanumeric LCD display is not working

    Are you using the busy signal or using delays between commands? If the latter, up the delays a bit and see if it works any better. Bob
  12. BobK

    calculate high power led resistor

    The "star heatsink" is not a heatsink! It is meant to be attached to a heat sink. You can get away with running 1W ones without further heatsinking, but not 3 or 5. Bob
  13. BobK

    16 x 2 alphanumeric LCD display is not working

    Not working is not very descriptive. Bob
  14. BobK

    Microcontroller LED project.

    Yep, those are the same thing except $2 a piece instead of $0.29 for the ones I linked. Bob
  15. BobK

    mppt charge controller

    Agreed, boost topology has the power source connected all the time. Bob
  16. BobK

    Microcontroller LED project.

    Another option is WS2812B LEDs. These are RGB and controlled by a datastream. Power does not go through the micro at all, and you have complete control over the brightness and color of each LED. I just put 40 of these into a ballroom gown for my latest dance showcase (the lovely wife...
  17. BobK

    mppt charge controller

    But in the buck converter topology the source is completely disconnected during the off part of the duty cycle. The smoothing of the output occurs because current continues to flow in the inductor. So, the panel is not producing any current during the off part of the cycle. Are you...
  18. BobK

    mppt charge controller

    Hmm. So the battery must have non-linear behavior when charging. I guess that makes sense, but I never thought about it. I always assumed the current was controlled by the voltage input and the internal resistance of the battery. Any idea how one would model this in LTSPICE? The other thing...
  19. BobK

    PWM setup

    Agree with @dave9, there is nothing wrong with running the 3W LEDs (if you use 7-12 of them in series) at 350mA. Bob
  20. BobK

    LED Christmas Village lighting help needed!

    Agree with @kellys_eye, using mains directly would be dangerous, especially with something kids would be around and probably want to examine. Bob
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