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Type: Posts; User: gdjacobs

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  1. Does anyone have a matrix showing plug types and...

    Does anyone have a matrix showing plug types and pin mapping for modular PSUs?
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    They're very similar to how a stepper motor or an...

    They're very similar to how a stepper motor or an AC synchronous motor operate, although they can run as induction motors as well.

    I doubt the ones you've linked are truly brushless, though, as...
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    Split phases are equal magnitude and 180 degrees...

    Split phases are equal magnitude and 180 degrees out of phase. Each phase is the opposite pole of a transformer and the neutral is a center tap. The biggest potential issue is with earthing.

    ...
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    Power loss from the MOSFETs will consist of...

    Power loss from the MOSFETs will consist of conduction losses and switching losses. The bulk of power loss will be during switching.

    Power loss while in conduction will be equal to the duty cycle...
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    Yes, two different styles of control panel and a...

    Yes, two different styles of control panel and a complete lack of organization on the start menu (unless you go full billboard style) were such an improvement. Quasi stable system updates (because...
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    Switching losses increase linearly with clock...

    Switching losses increase linearly with clock frequency. However, increased voltage is often required to increase clock speed and voltage will generally increase power consumption quadratically.
  7. Thread: Active PFC

    by gdjacobs
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    2,118

    Yes, just trying to be precise.

    Yes, just trying to be precise.
  8. Thread: Active PFC

    by gdjacobs
    Replies
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    2,118

    Resistive loads are linear, but not just...

    Resistive loads are linear, but not just resistive loads. Any electronic load that adds or removes harmonic content (i.e. transistors, diodes, saturated magnetics) is not linear.
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    As noted by others: spare the flux, spoil the...

    As noted by others: spare the flux, spoil the joint. For SMT, I will often pre-tin one of the pads while leaving the others clean and use some down pressure with the iron for that joint. Then you can...
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    Isolation transformers are a very useful tool. ...

    Isolation transformers are a very useful tool.


    Scopemeters are very nice if pricey.


    Capture and data connectivity is common now, but it's been available for many years.


    1) It never...
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    That's what up front spending on process...

    That's what up front spending on process improvement is for.

    BGA had a much rougher transition than wave solder applications as far as defect rates.
  12. Thread: Teapo

    by gdjacobs
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    11,495

    Delta, for instance, uses mid-tier caps (like...

    Delta, for instance, uses mid-tier caps (like Teapo) in their designs all the time. However, because of their combination of experience and engineering standards, they seem to be able to use them...
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    My dream UPS would act more like an active...

    My dream UPS would act more like an active filter. The PLL would stay locked in at all times and the mosfets or IGBTs would begin injecting (or sinking) power extremely rapidly. Using sigma-delta...
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    It was only improper probing if Dr. Lewin wanted...

    It was only improper probing if Dr. Lewin wanted to exclude lead inductance from influencing his measurement (which he could do by twisted pairs or by orienting the loop formed by the leads parallel...
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    Are you comfortable with the concept that work...

    Are you comfortable with the concept that work done by a charge moving through a magnetic field (or any other non-conservative field) is no longer path independent?
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    I'm guessing it's failing when restoring from a...

    I'm guessing it's failing when restoring from a table dump. If all else fails, you can implement a script to iterate over all the records in the troublesome table copying from the old server install...
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    In other words: Unlike the rectifier circuit,...

    In other words:

    Unlike the rectifier circuit, the APFC circuit draws current and charges the bulk caps under active control. The APFC circuit can adjust it's current draw according to what, in...
  18. Just to explain for OP, gold is 10^-1 as a...

    Just to explain for OP, gold is 10^-1 as a multiplier, silver is 10^-2.
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    You have to look beyond it's roots in engineering.

    You have to look beyond it's roots in engineering.
  20. Thread: PFC thoughts

    by gdjacobs
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    3,316

    Well, P = I dot V. If the objective is to...

    Well, P = I dot V. If the objective is to minimize I while P and V are constant, obviously the phase between any components should be zero. Also, any harmonics from a non sinusoidal current waveform...
  21. I see PSU sections die fairly often due to MLCC...

    I see PSU sections die fairly often due to MLCC caps failed short, usually in laptops. As for failure at EOL, even coils and transformers have an end to their bathtub curve, although it's reasonably...
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    I believe my copy is the 6th Ed as well. I hope...

    I believe my copy is the 6th Ed as well. I hope you enjoy reading it.
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    27,969

    Yes, in a general sense, you have to account for...

    Yes, in a general sense, you have to account for complexes of reactive components. Even for pure DC, though, components often have complex behavior that can't be modeled as pure resistance (although...
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    Most primary overhead distribution lines (2400V...

    Most primary overhead distribution lines (2400V residential, 12.5kV, and 14.4kV -- all phase to ground) use non-insulated Al, Al-Steel, or all steel wire. That way, the lines are a bit more...
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    Usually because R is an end product of actually...

    Usually because R is an end product of actually measuring voltage and current (and phase) through a circuit branch.. More often than not, components will be dynamic with different operating...
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