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  1. T

    Thevenins and nortons circuit help

    lp2014needhelp, consider the schematic shown in post #6. Calculate the equivalent resistance of R2, R3 and R6; replace those three with a resistor labeled Rx. Now the current out of the battery is Ib = 12/(R1+Rx+R5) The voltage across Rx is Vx = Ib*Rx. Now R3 and R6 form a voltage divider...
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    A bit of physics

    Is that a metric ton?
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    Phase Shift Oscillator

    The frequency of oscillation becomes SQRT(321)/5 * 1/(2 Pi R C) The required gain becomes 9.272 rather than 29.
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    Phase Shift Oscillator

    When all the stages are buffered as in Figure 15.16 of this pdf: http://www.ti.com/lit/ml/sloa087/sloa087.pdf Then the SQRT(3) formula applies (the RG resistor loads the last RC stage, so the formula isn't exactly right even with the buffering). If there are no buffers between stages, then...
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    Phase Shift Oscillator

    The phase shift of each RC stage is not 60°. See this page: http://wps.prenhall.com/chet_paynter_introduct_6/0,5779,426330-,00.html second paragraph under Figure 18-3
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    Measuring the inductance of a wirewound resistor

    It's called "understatement". :p I looked around some more and found a 20 W 1 ohm resistor; it measured .49 uH
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    Measuring the inductance of a wirewound resistor

    I gathered up some power resistors similar to what Steve is measuring. They're not all 50 watts; some are 10 watts, some are 20 watts. They have resistances of 10k, 1.2k, 1k, 404, 100, 10 ohms. I swept them over a frequency range of 100 Hz to 1 MHz, displaying their inductances on a Hioki...
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    Need help with Wien-Bridge Oscillator

    Fortunately that's easy to fix.
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    Need help with Wien-Bridge Oscillator

    You might find the lead article in this issue of the HP Journal interesting and relevant: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1960-04.pdf
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    LC meter accuracy

    You're quite right. This works:
  11. T

    Woo-Woo Power saving speculation

    It kind of looks like we have a thought disorder here. See: http://en.wikipedia.org/wiki/Thought_disorder Maybe Tangentiality: http://en.wikipedia.org/wiki/Tangentiality Or maybe Flight of Ideas: http://medical-dictionary.thefreedictionary.com/flight+of+ideas
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    Mind boggling question

    The fact that Mathcad did not reduce its result to something simple doesn't mean that there isn't a simple solution. Had you made the substitution ZL -> RL + j XL in post #3 before you solved for w, you would have had the same problem of a very large output from Mathcad.. But, it isn't...
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    Mind boggling question

    By "final result", I mean the result required by the original problem, which is the determination of Rx and Lx such that the load current (current in ZL) is zero. You have found an expression for VL; certainly that expression involves Zs and ZL. Now you need to use that expression to...
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    Mind boggling question

    If the source and load impedances are included, they drop out of the final result.
  15. T

    Mind boggling question

    Isn't the idea to help the student rather than do all the work for him?
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    Mind boggling question

    This is a bridged T notch filter (look up on the web). They want you to determine the values of Rx and Lx that will make the output zero at some particular frequency.
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    LCR circuit calculations

    Most of your values have some rounding error, but the angles of I2 and I3 seem to have greater error than can be blamed on rounding. See the correct values in red. The voltmeter will read the magnitude of V23 (unless it's a vector voltmeter) which is 18.2 volts. I assume the wattmeter is to...
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    Calculate Current, Power, EMS..

    Make the changes shown in red: If you put your voltmeter back the way it was in the first post of this thread, then Vb will be the voltage it will read.
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    Calculate Current, Power, EMS..

    What is an absolute voltage? AFAIK, there's no such thing. Voltages must be measured with respect to some reference. That's why a voltmeter has two probes---one to connect to the point where you want to measure the voltage and one to connect to the reference. When you said "...how I would...
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    Calculate Current, Power, EMS..

    What is a phantom reference? My comments start out talking about the case where the reference node IS the lower right hand corner. I believe your second equation, left side was intended to be for that case. Then the R5 in the denominator of the last term was in error. When the R5 element...
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