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  1. dorke

    mesh analysis PROBLEM

    Well, your teacher is correct. The definition of a Mesh(in planar circuits) is: A loop which does not enclose any other loops. That number here is indeed 13 as shown. A different question is what is the minimal number of mesh equations needed to "solve" this circuit. That number here is 1...
  2. dorke

    5000W high power mosfet

    Yes, very likely. But that is also a question of space and price and even inventories.
  3. dorke

    UPS Failure

    That board looks like something designed and manufactured in the 80's... You need a service manual or at least a schematic to fix it.
  4. dorke

    5000W high power mosfet

    1st, I need to correct #4 to be less than 100W. This taking into account that the Mosfet is constantly on(PWM=100%). 2nd, This module is very cramped together and the packages used are not the best at dissipating heat. 3rd, What kid is offering is 100% over-design. What I call "USSR style...
  5. dorke

    5000W high power mosfet

    Yes, Because the mosfet in "PWM mode" works in two states only: either on or off ,in these states the power dissipation of the mosfet is very low. In the off state: it is zero. In the on state: it will depend on the Current and the RDS of the Mosfet. For a 100A mosfet the RDS is below 10m-ohm...
  6. dorke

    5000W high power mosfet

    You should use a 100A Mosfet(preferably higher current) with breakdown voltage over 45V . A 150A/60V one should do and scohttky diode protection is advised. I don't know how to put this gently... Your question(5000W etc.) suggest there is a lot you need to learn and experience. Maybe this kind...
  7. dorke

    DSP/Amp Problem (Reversed Polarity)

    I think not, You have a 25A fuse on that line,worth trying in the car. Can you see how much current is drawn from the PS? This scenario is also possible: One of the voltages that U4 generates is overloaded/shorted so that when U4 is activated it will draw a large current that will cause the...
  8. dorke

    DSP/Amp Problem (Reversed Polarity)

    The first test that shows a drop of VBAT and VCAR from 12V to less than 9V need to be fixed first. Are you using a Power Supply or the Car Battery when testing? A power-supply may enter current limit condition and thus drop it's voltage.
  9. dorke

    noisy differential signal

    Well steve, Not so, the termination of RS-422 is always(!) at the receiving side (the end of the transmission line). RS-422 supports point to multi-point (one driver and many receivers)so the the "end of the transmission line" is at the farthest away receiver. If there are long stubs along the...
  10. dorke

    noisy differential signal

    For RS-422 termination is needed at the receiving-end and it depends on the type of twisted wires you use(they are twisted,right?). What you did is the correct way to do it, nothing else is required. BTW, what is the rate of the signaling and what is the distance?
  11. dorke

    Filtering for USB5V

    What is "clean"? First thing is defining the noise level you need to achieve.
  12. dorke

    Xk-2412dc power supply module

    The two above are not "equal",don't seem to be of the same thing-markings differ. What do you need the schematic for? repair?other?
  13. dorke

    Unknown LCD pin outs mapping related

    Well, Where was it pulled from? if you know that it may help you. Surely you don't need all the "dedicated" symbols on it, maybe just the numerical display? If so, it would be easier to get a known LCD to work with.
  14. dorke

    Xk-2412dc power supply module

    Not easy to find schematics for Chinese products on the web. Do you have it? It looks simple enough to make a schematic from the physical thing.
  15. dorke

    Thermometrics Thermistor & IRC Negative Balco

    Maybe this can help
  16. dorke

    What parts do I need?

    Welcome Pete, 1Km, Is it "open air" ,not in closed buildings? Why don't you use walkies-talkies? Get 11 of them, 10 fixed and 1 (or more)at the "assisting station". In this why the person needing assistance can describe what the problem is ,and maybe even be assisted remotely (saving the 1Km...
  17. dorke

    DSP/Amp Problem (Reversed Polarity)

    Lets give a try. First thing is to disconnect the speakers from the unit. Then check that VCAR is the same as VBAT about 12V (green in the pic below),check it while pressing the reset and releasing it. In pink are the diodes and caps you looked at. Then you should check all the voltages on...
  18. dorke

    Potentiometer as a Variable Resistor

    It is possible, use a linear variable regulator IC(LM317 and the like) or module. What is the problem with using "anything digital, buck, switched"?
  19. dorke

    Sound level meter

    It is confusing. Try another module ,there are so many to choose from... BTW, Is this a "school project "? What μC are you using?
  20. dorke

    Potentiometer as a Variable Resistor

    What you actually need is an adjustable step-down DC to DC converter 12V to (3-8)V at 1A or more (they are dirt cheap this days). Like this one. or a one with a digital readout like this one. If the number of tools you are using is small, you can consider attaching a dedicated converter to...
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