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  1. I

    Speaker - frequency and impedance

    Be careful here……… mechanical and electrical resonance ARE NOT THE SAME THING!!! Electrical resonance is a second order phenomena (2 reactive elements). As for the dampening effect of a shorted voice coil, how about the induced field in the coil opposing the magnets flux. If you removed the...
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    how to find out the frequency of an amplifier

    Yes, that is exactly what I said above, but that's not what your earlier response was when taken/read literally. It would be helpful to throw in "the math", so there's no misunderstanding. You never answered my earlier question
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    how to find out the frequency of an amplifier

    OK............. let's call it a decrease in attenuation, which from a certain point of view is gain. As you go below 20Hz  towards 0, the voltage across the resistor (in this case the speaker) will continue to decrease... this is basic "CR" circuit stuff, the transfer function is...
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    Latching comparator help

    I would move the LED and current limiting resistor to the collector and add a base resistor to the transistor. Also, while the output is at the minus rail, the output clamp diode is making the poor 741 work really hard!!!
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    how to find out the frequency of an amplifier

    I'm missing something here................... If a capacitive coupled signal is driving a resistive load, this is like a high pass filter!!!!! Yes, you do apply the Maximum Power Transfer Theorem  and the corner frequency will be, f=1/(2* pi*R*C) (the -3dB point, a.k.a. half power point), but...
  6. I

    About analog Multiplier

    Yes you can. You need 2 log amplifiers feeding an "adder" and the output of the adder needs to be fed through an anti-log amp. But why "over think the plumbing"!!!!
  7. I

    Range of Digital Voltmeter

    The range isn't "really" what is you think.... for example the 200mV range is 199.9 mV and the 2 volt range is really 1.999V. It's the leading digit.
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    LED amperage question

    Not exactly.... a LED will draw whatever current you allow it to by means of the current limit resistor! As you allow more current flow, it will get brighter and as it gets brighter, the LED (diode) forward voltage increases as dictated by the diode equation. Therefore,  the "exact" amount is a...
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    About analog Multiplier

    Try.......... http://www.analog.com/en/prod/0%2C2877%2CAD633%2C00.html
  10. I

    RLC phase relative to source

    Phase shift is the relative shift of current or voltage of a point in respect to some reference. As soon as you introduce a time varying signal and you have capacitive and/or inductive elements, you will have phase shift. What 3 voltages? How and of what, did you "set" the phase shift?
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    Which one of these is correct!? (State technique for an electrical network)

    First, these to circuits are not exactly the same. They are however both 2nd order circuits. The professor is solving the system with state-space equations while the other solution is via differential equations. Since the circuits are different, why would you expect the solutions to be the same??
  12. I

    Audio to DC Motor Driver

    OK... say you go full wave. All that that will do is make the motor turn for as long as there is a signal in either polarity, provided it's "low" enough to turn on the PNP. In other words, signal = mouth open and, no signal = mouth closed. I would have thought the intent was to have motion to...
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    Audio to DC Motor Driver

    Without taking into consideration the current needed to drive the motor, I don't see this circuit as being that bad, "for what it is", a cheap way to periodically activate a motor. Sure, with a servo you could get "movement" proportional to input amplitude, but the circuit isn't so simple...
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    Speaker - frequency and impedance

    Resonance with what? What is the other element, and how is it held constant?
  15. I

    Speaker - frequency and impedance

    A little off subject, but I have a question............. Obviously a speakers impedance isn't measured at DC. At what frequeny are speakers characterized for impedance??
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    Capacitor circuit design...

    To generate high flux, you need high current NOT high volts!!!!! I would think that this is an experiment where you want to keep the voltage as low as possible, but still be able to generate a high flux field!!!!!
  17. I

    a regular transformer

    The gap is not fixed.... can vary. Look at some gapped core data sheets, you will find something called inductance factor (nH/1000turns), typical numbers you'll see are 100, 160 and 250. Each of these has a different gap. To really understand this, and get a feel for how diffeent parameters...
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    Transformer Winding Sequence Question

    Here you go................. https://www.surplussales.com/Wire-Cable/LitzWire.html In regards to: L2 RM10PA250-3F3 PHILIPS 10T PRIMARY LITZ(2X10X,1) 60T SECONDARY LITZ(1X15X,1) WINDING SEQUENCE (PRIM-10T, SEC-30T, PRIM-10T,SEC-30T, PRIM-10T) This is a coupled inductor. The core is a...
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    Variable DC Power Supply

    Not always, the MPSA17 has a min V(br)EBO of 15V while a MPSH11 is 3V. The diode equation tells us that the "normal" P-N junction has a drift of ~2mV/
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    Capacitor circuit design...

    Wow.............. a 2F capacitor!!!!! It must have a VERY SMALL voltage rating (must be a hold-up cap of some kind). Keeping integration out of it, it all goes back to E=L*di/dt  and  i=C*dv/dt If the cap voltage is indeed low, the DC resistance of the coil will also have to be very low so...
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