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Type: Posts; User: wwfeldman

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  1. Closed: Re: Boost PFC controller must contain anti-distortion feature for zero crossings

    LT1248 is from about 1999
    see what looks like a date code at the bottom of the last page
    1248fd LT/GP 0799 2K REV D • PRINTED IN USA
    i think 0799 is a date, july 1999
    package is a 16 pin plastic...
  2. Closed: Re: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

    all of these appeals to classical physics are a little bogus,
    and there are no really good analogies, however:

    consider a rocket launched at escape velocity
    it is moving at escape velocity and...
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    Closed: Re: MOSFET Gets Hot in H Bridge

    the source of the N channel FETs is at 0V
    the gate of the N channel FETs is at 12V or 0V, depending on the state of the transistor
    therefore the N channel FET is ON or OFF depending on the...
  4. Closed: Re: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

    response from a friend:
    1) there are some errors in the discussion about hydrogen in post #2
    2) Ec, the energy of the low limit of the conduction band is not specifically related to potential...
  5. Closed: Re: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

    waiting on a response from a friend
  6. Closed: Re: Calculating electromagnet – magnetism vs heat

    How are you powering the electromagnet?
    you will need to provide a path for the current when you turn it off.
    if you do not, you can get very large voltage spikes that can damage the equipment.
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    Closed: Re: Decoupling CAP using MOSFET?

    i expect you can get the same or more pF with a capacitor
    and one less lead to connect
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    Closed: Re: Introductory literature on PLD

    good start
    read the data sheet
    get a development board and download the software
    go through the examples

    when you run into a problem,
    show the work you did, what the computer told you,
    and...
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    Closed: Re: Converting drill file in um to mm

    i think you did good
    you can stop banging your head against the wall

    my apologies about the metric system lesson
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    Closed: Re: Interdigitated capacitors

    same as any other capacitor
    basic model two plates, area A, charge q, separation d, dielectric k, etc

    then there's another one in series
    and another in series etc
    ...
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    Closed: Re: Converting drill file in um to mm

    mm is millimeter, 10^-3 m
    um is micrometer, 10^-6 m

    converting requires moving decimal point 3 places corresponding to multiplying or dividing by 1000,
    depending one which way you're going.
    ...
  12. [SOLVED]Closed: Re: Stacking diodes for high voltage rectification

    100 uf4007 plus 100 R & C for snubber plus 100 voltage sharing resistor
    vs
    10 K50UF plus 10 R & C for snubber plus 10 voltage sharing resistors

    now compare board space, parts cost, inventory...
  13. Closed: Re: Will I be able to drive LED with attached analog circuit ?

    i think it will work
    but the LED is always on, and there are simpler circuits to just turn on the the LED
    at 3.5 mA the LED will not be very bright.
  14. [SOLVED]Closed: Re: stacking diodes for high voltage rectification

    see this thread
    Bridge Rectifier won't Rectify

    you would need some way to guarantee that all of the diodes carried their share of the voltage

    since the uf4007 is rated at 1000 V, 100 of them...
  15. Closed: Re: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

    An attempt:

    as you know:
    consider the bohr model of hydrogen:
    an electron can orbit the nucleus only in specific quantum levels
    the lowest level, n = 1, is at -13.6 eV
    the next level, n = 2,...
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    Closed: Re: damaged remote control

    treat it like a wet cell phone

    put it into a container with rice all around for a day or 2 to dry it out
    get all of the rice dust off it
    then put it back together with a fresh battery.
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    Closed: Re: Single conductor inside hollow conductor

    if anyone wishes to continue he discussion of potential, emf and voltage, etc,
    please start a new thread under physics
    as this seems somewhat far afield from kajunbee's question
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    Closed: Re: Single conductor inside hollow conductor

    @easy peasy
    emf and potential are both measured in volts
    when the "voltage" is caused by charges, it is potential and the potential difference between two locations is the voltage we measure
    when...
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    Closed: Re: Whats the best way to ESD damage a PCB

    it also depends on the humidity in the air
    this time of year, north america, europe etc have relatively high humidity and
    static charge does not build up

    if you did the carpet shuffle, or the...
  20. Closed: Re: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transform

    this test is accomplished by tieing all of the primary leads together and all of the secondary(ies) leads together
    and then applying 3750 VAC

    3 mA seems like a lot of leakage
  21. Closed: Re: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transform

    the transformer tested for a longer time is likely built better

    i expect more critical application require a longer isolation test

    what is the 3mA about?
  22. Closed: Re: Nominal current of diode bridge rectifier

    the data sheet says rectangular pulses, 1/3 of the time, as noted above, 90A output current

    conduction by any one diode 1/3 of the time is the most one would expect from a 3 phase sine wave input...
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    [SOLVED]Closed: Re: 12 vdc led running very hot

    please provide the circuit the LEDs are in, the part number of the LED
    and any known voltages or currents
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    Closed: Re: Isolate R37 from Equation

    try this:
    apply voltage divider at the + input of the op amp V+ = ...

    assuming a perfect op amp, V- and output = V+

    combine R25 and R28 to one equivalent resistor

    assuming Vo is open,...
  25. Closed: Re: Drive motor through IRF520 MOSFET module and Arduino

    please draw the circuit for the arduino, the MOSFET Drive Module and the motor
    show the connections between the arduino the mosfet driver and from the mosfet driver to the motor
    show all voltage...
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