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  1. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    A common ground for both +5 and +12 is necessary for the circuit to work. Also the three ground connections indicated in the schematic must also connect to said common ground. I imagine that was obvious. I suggest using your scope to look at +12V where it enters my circuit. This may reveal...
  2. CircutScoper

    Power Reduction Query

    A series stack of rectifier diodes (e.g. 1N5400 or 1N5404) in series with the motor might be a better solution than a resistor because speed regulation would be better. Each diode would subtract about 0.7V from the motor drive and (very) roughly 20% from the speed. So two or three should cut...
  3. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Just for general interest's sake, R4 R5 (your R1 R2) aren't really an attenuator. R4 sets the 20ms timeconstant of the differentiator while R5's purpose is to reduce the difference in 12V ON/OFF output pulse widths that would otherwise result from the ratio of common-emitter vs common-base...
  4. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Ewww! Signal flow is right to left in Q1's emitter and in many resistor meanders. Also, I gather you can never draw a feedback connection. That's kind'a limiting, ain't it?
  5. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    R1 is a pullup (bias) resistor and not part of an attenuator. Signal flow is already left to right with 12V the input, 12V ON and 12V OFF logic level outputs. Happy to help. Edit: Component designators here refer to my schematic.
  6. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Thanks. "Unencumbered" schematic attached. Since you feel it needs further improvement, I invite you to redraw it. Please.
  7. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Provided that the rise and fall times of 12V is 0.01s or less, the circuit will work as drawn. If 12V rise/fall is slower than that, the capacitor may need to be increased to 100uF or 1000uF. What did you assume in your simulation?
  8. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    ...Besides the typing efficiency (2 keystrokes versus 25 (!))... ROFL! On the subject of "typing efficiency," how many keystrokes did you just invest in complaining about my simple schematic? Please help me out here, because I lost count. :) ...
  9. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Good point. Maybe the cap needs to be 1000uF. Meanwhile, maybe instead of designators we can make do with descriptors. For example we have the common base transistor and the common emitter transistor. Happy to help.
  10. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    This circuit should do what you want..
  11. CircutScoper

    Inrush Current for Capacitive Load

    As explained, a timeconstant (T=RC) of 1us and 120A inrush result from Harald's simulation when R1 = 0.1 Ohms, which is a fairly plausible value. 0.0001 Ohms, as required for RC = 1ns, is (much) less so. Meanwhile, the inrush energy dissipation calculation (1/2CV^2) is totally independent of R1.
  12. CircutScoper

    Inrush Current for Capacitive Load

    That's the reason 1/(2piFC) is of no help in quantifying and designing for the inrush. One way that is useful, however, is to consider the associated energy the inrush will dissipate, which is easily calculated thusly. The energy drawn from the power supply during the inrush = QV = (CV)V =...
  13. CircutScoper

    Inrush Current for Capacitive Load

    Try looking at it this way. The charge Q (Coulombs) stored by a capacitor C (Farads) with V (Volts) applied Q = CV = 120uCb in your example of a 10uF cap when it's charged to 12V. That 120uCb of charge has to be transferred from the 12V supply to the cap when the supply is switched on. The...
  14. CircutScoper

    Potential energy of suspended mass expressed in kWh

    I agree. But you misspelled "screwed."
  15. CircutScoper

    Lightning in a bottle

    And of course you have to pick a different place every time.
  16. CircutScoper

    Why a Diode in this circuit?

    Why a diode, indeed. Due to the voltage drop of D2 plus the logic-low voltage of the MCU output pin, it's likely Q1 will not turn off completely -- especially when its significant power dissipation heats it up. This will cause the LEDs to glow at least dimly when they're supposed to be...
  17. CircutScoper

    Is an MPPT controller just basically a buck/boost converter with extras?

    Excellent explanation! Here's a simple example of an analog MPPT battery charger. https://www.mikrocontroller.net/attachment/74140/2IFD_MPPT_.pdf
  18. CircutScoper

    How do I make an opamp stereo mixer?

    What about just connecting the earphones in series to sum (mix) the outputs of the phone and game? Blue is the case of two stereo outputs, Yellow one stereo and one mono
  19. CircutScoper

    How do I make an opamp stereo mixer?

    The mic input.
  20. CircutScoper

    How do I make an opamp stereo mixer?

    Good point, but only his microphone input requires gain, and even that may not be a low enough level to benefit from a low-noise amp.
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