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  1. crutschow

    Swapping diode for P-MOSFET: reverse spike protection

    No, that is the correct orientation to block a reverse power connection, which is its purpose.
  2. crutschow

    Multiple isolated devices and GND

    I see no problem with connecting all the common grounds together.
  3. crutschow

    Swapping diode for P-MOSFET: reverse spike protection

    Electrically there's no change when you reverse the order of two series elements. Why would you think there is? You circuit is still not protected from high energy spikes.
  4. crutschow

    Multiple isolated devices and GND

    If the modules sent signals to each other and/or share a power supply, then they all need to share a common ground.
  5. crutschow

    Swapping diode for P-MOSFET: reverse spike protection

    That will protect your diode but not the circuit, since now there is noting to keep circuit voltage from rising way above the TVS voltage. You need a small resistor in series so that your circuit only sees the TVS voltage, while also limiting the TVS current.
  6. crutschow

    Swapping diode for P-MOSFET: reverse spike protection

    What do you think needs a heatsink and fan? You don't need either if the load is only 50mA. The one in the referenced schematic.
  7. crutschow

    Swapping diode for P-MOSFET: reverse spike protection

    Why do you want to use a more expensive MOSFET to replace a diode? With a 3.3V output from the regulator, the 0.7V drop for the 13.8V input will just reduce it to about 13.1V, which will have no effect on proper circuit operation. And why did you get rid of the series resistor? That helps...
  8. crutschow

    Op Amp how does the feedback factor works ?

    You are confusing the feedback factor (gain) with the output voltage from that gain. If the input is 0V, then the output will be the gain x 0V = 0V. The voltage being amplified has no effect on the gain of the circuit. Make sense?
  9. crutschow

    Why do some devices turn on with the mains before the "On" button is pressed?

    But that is only practical for things you don't use often. Perhaps easier to plug into a power strip with a switch.
  10. crutschow

    Why do some devices turn on with the mains before the "On" button is pressed?

    That fault is especially annoying if the main's power goes out, since you then have to remember to go around and turn them all off after the power returns.
  11. crutschow

    Why do some devices turn on with the mains before the "On" button is pressed?

    My thought is that it's just a bad/lazy design. They didn't bother to insure that the device would not power up when first plugged in.
  12. crutschow

    HOW TO Convert 12v to 13v

    How can that questioned be answered with no information about the adapter?
  13. crutschow

    Audio Source Switching

    What is the nature of this noise? What does it sound like?
  14. crutschow

    HOW TO Convert 12v to 13v

    To increase a voltage you need a boost (or buck-boost) switching regulator. As Harold noted, an off-the-shelf module will be the simplest and cheapest way to do that. Otherwise buy an adapter with a higher voltage.
  15. crutschow

    Temporary Delay Circuit

    Since I haven't seen a full schematic, only a simplified diagram of the connections, I cannot make an informed answer to that question. If you built the circuit without a schematic, then how do you know it's correct?
  16. crutschow

    Temporary Delay Circuit

    It would appear that there is a hidden load on one of the OR gate outputs. Either that, or you have a bad OR gate chip.
  17. crutschow

    Temporary Delay Circuit

    Don't see a reason for the overheating unless you were applying more than 5V for power or to any of the inputs, or had any of the outputs grounded or going to 5V. An exact schematic of all the gate connections (including unused gates, and power and ground) would help, as we seem to be missing...
  18. crutschow

    Temporary Delay Circuit

    I'll ask again. What OR gate are you using?
  19. crutschow

    Astable multivibrator circuit making me astable

    Great. It will step to 0, so you don't need to use 0.0001 (unless you want to). So why are they culling Cape Town's baboons (I assume you mean the animal, not some idiot humans)?
  20. crutschow

    Astable multivibrator circuit making me astable

    Great. In case you are not aware, you can change/step the wiper value as desired, to move the wiper from one end of the pot resistance to the other.
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