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  1. K

    filtering

    Thank you. Do you know of LC's being operated out of resonance? LC filtering is still popular.
  2. K

    filtering

    From what I gather, resonance allows for only about 65db/decade filtering. Is it okay to operate an LC away from resonance? Less filtering means less loss if you aim to conserve your bandwidth.
  3. K

    110v supply

    I think using one transformer is ideal. Wanting 110vac when your stuck with 130vac might not be worth it.
  4. K

    BJT biasing

    I've seen the constant current source in the opamp schematic. It's kind of a rudimentary one fashioned from a single transistor. Now, I thought it was just used as a general compliment to the design. I thought the high gain was due to driving the two or three bases simultaneusly. A constant...
  5. K

    BJT biasing

    You are right Audioguru. But with negative feedback, you are still trading one for the other. It is a system of impedances and voltage dividers. But if you say it's good, I would like to know the real reason behind it.
  6. K

    transmission lines

    My cable TV has a wide bandwidth too. Because the frequencies are realtively high, I could get the transmission line length perfect for one station if a wanted to. I could add a reasonable tuning stub, or even cut the line to the exact length. I don't think the TV is a good indicator of the...
  7. K

    transmission lines

    If you took a 50 ohm source, a 50 ohm cable, and a 50 ohm load and did not operate on the conditions of resonance, you would have a VERY LOW impedance as seen by the signal source. They say 200 KHz is the leveling frequency, but you would have to have a cable a mile long to not see a 50ohm...
  8. K

    class d amplifier

    I didn't know that, thank you.
  9. K

    class d amplifier

    The P channel needs to be on top, the N channel on the bottom.
  10. K

    transmission lines

    A series resonant circuit looks only to be the resistance of the coil. Outside the resonant frequency, it looks to be a capacitor or inductor, whichever takes precedence. It would seem to be the same with a cable. Add any reactive element, they call it a resonant line. A non resonant line would...
  11. K

    transmission lines

    Audioguru, We'll set the line, load, and source impedances properly for argument sake. As far as I know, the source sees parallel resonance, series resonance, a capacitor, or inductor. And since these conditions are determined by the load value and length of the line, these four conditions are...
  12. K

    BJT biasing

    I did not realize that the internal re could be as high as 61 ohms. Also notice that when you remove the capacitor, the distortion is lower because the signal impedance is higher. Often you want to select the two base bias resistors low enough so that the impedance seen by the signal is not...
  13. K

    BJT biasing

    Just reducing the gain helps. And why don't you see negative feedback on single transistors in every circuit. I see it some of the time. I don't see the feedback in the circuit.
  14. K

    preamp op amp circuit question

    Just wanted to touch on supply ripple noise. I applied a signal to the bases of two transistor, collectors connected together, for a gain of 1000, whatever it's called, and the 60 Hz supply ripple never made it to the output. The signal was there, gain of 1000, but the supply ripple disappeared...
  15. K

    BJT biasing

    Yes, I think so. But many high gain single opamp circuits exist, and they still sound okay on a speaker.
  16. K

    preamp op amp circuit question

    It's possible that it might oscillate. Mono meaning "one frequency" I think. Could be just a rudimentary oscillator. Does not appear to be a linear sort of amplifier.
  17. K

    transmission lines

    Isn't a 50 ohm termination much like a short?
  18. K

    transmission lines

    You know, I thought a tuning stub was to be shorted, instead I've seen it open.
  19. K

    transmission lines

    What about the parallel resonance and things?
  20. K

    a high pass filter question

    If you set in place reasonable constraints, it's difficult. Yes, you can say let's stick in a 100VDC supply there, let's use a wide variety of DC supply voltages here and there, let's raise the frequency so we can use some emitter capacitors, let's lower the transistor current so we can up the...
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