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Type: Posts; User: crutschow

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  1. Closed: Re: Cut-off current through an N-channel power MOSFET with negatively charged gate

    Gate curreent is always very low and independent of drain voltage, since the gate looks like a capacitor.

    What is the perceived problem you have?
  2. Closed: Re: How to switch feedback networsk in synchronous Step-Down Voltage Regulator?

    You don't need a negative voltage for an analog switch, such as a CD4066, unless you are switching a negative voltage.
  3. Closed: Re: Square wave generation without Microcontroller

    To generate that pulse train four times for each button press would require two multivibrators and a 2-bit counter.
    A mico would be a lot simpler and cheaper.
  4. Closed: Re: What is the Max RMS System Noise before 'hiss' is can be heard in Headphones.

    I'd say you want any noise to be at least 60dB below the maximum peak audio signal level, with 75dB or more desirable.
    Old analog audio tape recorders had a S/N of only about 45dB if I remember...
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    Closed: Re: TLV4172 low-cost substitute

    If it's dual power, why do you need rail-rail?
  6. Closed: Re: Use an OR wired with diodes to control the gate in a PMOSFET

    Since you still haven't clearly stated what you need, I can't help you any further.
  7. Closed: Re: Use an OR wired with diodes to control the gate in a PMOSFET

    That's only one input condition out of four possible.
    What about both inputs zero?
    What about both inputs one?
  8. Closed: Re: Use an OR wired with diodes to control the gate in a PMOSFET

    So what exactly is the intended function?
    I'm confused about that.
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    Closed: Re: output of the circuit

    Yes, the circuit will likely oscillate, but why do you want that?
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    Closed: Re: Stable PWM during Voltage Loss

    You'll need to use the big cap.

    But, if the interruption is only for 50µs, the cap shouldn't need to be that large.
  11. Closed: Re: MOSFET linear and saturation region operation

    Okay.
    But that's generally true for any parts in a feedback loop, not just MOSFETs.
    It you don't need the equations, don't use them.
    But they are necessary for a fundamental understanding of the...
  12. Closed: Re: MOSFET linear and saturation region operation

    Because that describes how the MOSFET responds to the gate-source voltage in the linear region.
    Just because you've never used that info doesn't mean no-one does.

    Besides, the info in the "linear...
  13. Closed: Re: MOSFET linear and saturation region operation

    Perhaps this diagram from Wikipedia will help clarify:

    154431



    There's no easy way to calculate the Vds required for a required resistor value since there's a wide variation in the Vgs...
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    Closed: Re: Differential probe build

    Post deleted.
  15. Closed: Re: diffrentiate between lost wire detection and zero input in a terminal

    I suggest you post a schematic of the exact input circuit you have, so we can avoid a game of 20 questions. :wink:
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    Closed: Re: NE555 astable frquency

    Since the frequency of the 555 doesn't vary much with the setting of the duty-cycle pot, the value you get using 1/2 the pot resistance should be good enough for a reasonable estimate of the...
  17. Closed: Re: What is the definition of the efficiency in energy harvesting circuit ??

    Efficiency is basically the harvested output power divided by the input power from the source.
  18. Closed: Re: overcurrent and reverse polarity protection

    R2 is only needed if the input voltage is higher than the Vgs(max) rating of the MOSFET.

    You leave the collector-emitter connection open.
    If you short that connection how could the transistor...
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    Closed: Re: 9V rechargeable battery circuit

    I suggest you accept no further circuits from this "friend" as he obviously does not know what he is doing.
  20. Closed: Re: UA78M33CDCY 3,3 volt regulator will not regulate at input voltage above 12 vol

    They are not necessarily rejects from a reputable manufacturer.
    Semiconductor plants in China actually produce counterfeit parts on purpose, obviously with little quality control, since their name...
  21. Closed: Re: UA78M33CDCY 3,3 volt regulator will not regulate at input voltage above 12 vol

    Bad or counterfeit semiconductor parts from China is very common.
    They seem to have no control over (or interest in controlling) the sale of such parts.
    Generally it's not worth taking the chance...
  22. Closed: Re: Designing a current source for an unknown load

    The easiest way is to simulate it with an analog simulator, such as the free LTspice from Analog Devices.

    Try a capacitor between the U20A output and its inverting (-) input to see if that helps...
  23. Closed: Re: Resistor terminating in anti-aliasing filter

    An anti-alias filter is used if you are sampling the signal, such as for A/D conversion, and the sample-rate is close to 1/2 the maximum frequency of interest.
    A filter is needed to remove any noise...
  24. Closed: Re: Impedance frequency curves for ferrite beads

    The region where the capacitance starts to dominate is to the right, as the impedance starts to decrease.
  25. Closed: Re: Designing a current source for an unknown load

    You should be able to drive it from the low side and get a clean 200us pulse.
    It's a lot easier to control the low side, then the high side.

    Post the complete constant-current circuit including...
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