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Type: Posts; User: JST

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  1. Maybe... depends what the real amplitude was... ...

    Maybe... depends what the real amplitude was... If actually 0.4V peak, not likely to be more than obnixiously noisy with EMI, not too damaging in most cases (there are exceptions, and some...
  2. And yet, that was "full fidelity", because there...

    And yet, that was "full fidelity", because there you were, and there they were, and nothing electronic was between you and them......!

    That is yet another amusing thing about the sound biz.... ...
  3. The scale for the yellow trace is 200...

    The scale for the yellow trace is 200 mV/division. I assume that there must be an uncorrected scale factor due to whatever pickup was in use*, because the total amount of noise based on the...
  4. Speakers are an odd thing..... If you get the...

    Speakers are an odd thing.....

    If you get the speaker components set up (in the design of the speaker assembly) to cause the sound to arrive at the listener's ears timed correctly, the frequency...
  5. Thread: OT Arc flash video

    by JST
    Replies
    12
    Views
    946

    True! The only good news is that it also...

    True!

    The only good news is that it also reduces the fault current so that the energy level potential is lower also (which is basically saying the same thing as you did), so the power in any arc...
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    352

    if you have any decent soldering skills, you...

    if you have any decent soldering skills, you might look inside that unit.

    I saw a bad one once, and fixed it. The problem was a combination of lead-free solder and stupid engineers.

    The...
  7. You may not need any extra resistor, since it...

    You may not need any extra resistor, since it does not seem to be called out.

    the 2k ohm pot will draw only 6 mA, well below the 20 mA limit.

    You want a low value potentiometer, so that the...
  8. Eric Clapton is nutty if he believes that, at...

    Eric Clapton is nutty if he believes that, at least if the fuses are all nominally the correct typefor the power/voltage/current.



    The impedance makes no particular difference if connected to a...
  9. As far as the earphones, expensive may be better,...

    As far as the earphones, expensive may be better, or not. You are thinking right, in that the amp needs to be able to drive whatever you have decently, or the amp will make the earphones sound...
  10. Most of the filters are aimed at what it appears...

    Most of the filters are aimed at what it appears may be higher frequency ranges than what he may be having trouble with.

    Filters for that current etc are not cheap, and while they are less...
  11. That's fair. But, as far as problem solving,...

    That's fair.

    But, as far as problem solving, where we are at now is that there has been enough info given to suggest tests that would better zero-in on the problem.

    So, until something like...
  12. Absolute rule number ONE in EMI...

    Absolute rule number ONE in EMI fixing/remediation, is to "know thy enemy". That means to look at the line with spectrum analyzer, or even just a 'scope. Find out where in the spectrum the issues...
  13. That range is reasonable, and will probably keep...

    That range is reasonable, and will probably keep you out of trouble on cooling, also. Slower motor speed leads to less fan cooling as well, but 3:1 is reasonable.

    You can also over-speed...
  14. Replies
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    862

    If you have one, you then need a product to make...

    If you have one, you then need a product to make with it, or it is a waste of space. The product needs to be a volume product, but it need not be high dollar per each, depending on production rate....
  15. Be aware that slowing via a VFD is not problem...

    Be aware that slowing via a VFD is not problem free.

    The problem that is most troublesome is that you do not change torque when you slow the motor with a VFD. So the power available is...
  16. 1.5 HP derated to 50% is fine. Transformer on...

    1.5 HP derated to 50% is fine.

    Transformer on input, going into a high voltage VFD if you need 460V.
  17. You want to get a pipe under concrete, the...

    You want to get a pipe under concrete, the easiest way to do it is to dig a hole to one side, a longish hole.... Dig a hole the other side to aim at. Then "water drill" it through.

    Hose on the...
  18. Thread: Flat Belt slippage

    by JST
    Replies
    14
    Views
    1,074

    The rule with flat belts is that you start with...

    The rule with flat belts is that you start with enough tension that when the "loose" side is getting down toward zero tension, you have more than enough tight side tension to transmit the power.
    ...
  19. Thread: wiring 110v

    by JST
    Replies
    8
    Views
    472

    Well you just had to mention that name.... I'm...

    Well you just had to mention that name.... I'm tired of supporting those dang things.

    Yep it's gonna be thread locky-poo now.
  20. You need to have the capability to run the motors...

    You need to have the capability to run the motors you want to run, and to start any of them at the same time as running any motors that may need to be on. Figure the current surge from the kVA class...
  21. 1 HP VFDs exist, and if they have the current...

    1 HP VFDs exist, and if they have the current capability, which should not be an issue because you only need 0.7 HP, are all you need.

    I would not go too high, as in much if any over 2 HP, because...
  22. My first question is whether the voltage changes...

    My first question is whether the voltage changes when you turn on the PP?

    Lower voltage might mean more current and more hum from some loads. I don't know that lights are one that would do...
  23. The nominal voltage is, as a standard practice,...

    The nominal voltage is, as a standard practice, quoted line-to-line. So if the motor is set up for 230V 3 phase, then it will not matter what the internal structure of the windings is, any motor...
  24. It IS possible to just switch a resistor in and...

    It IS possible to just switch a resistor in and out as needed, if you set the "off" and "on" points correctly. The PWM is slicker, of course.

    There is also the point that the resistor may need...
  25. Replies
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    497

    It appears to shift the iron to the rotating...

    It appears to shift the iron to the rotating parts, and to rely on the thin-ness of the PCB to essentially replace the air gaps and magnetic reluctance of the iron in regular motors. Think of a...
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