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  1. R

    i need someone to look at this circuit before my teacher will get it

    Increasing the motor current by increasing the load risks burning out the windings. You want to keep the voltage up so that the motor will demand less of a current increase. If the motor needs more power, it has to be supplied, or the motor will not perform according to its specfications. Ratch
  2. R

    Accuracy Component Tester.

    What is it, and how is it measured externally? Ratch
  3. R

    Accuracy Component Tester.

    High precision does not mean anything when measuring the resistance of semiconductors. The resistance varies depending on the voltage applied. As I said before, they do not follow Ohm's law. Ratch
  4. R

    Accuracy Component Tester.

    Too bad this testor is not manufactured anymore. It did a quick check on a transistor by determining if it could invert a pulse. http://www.cbtricks.com/miscellaneous/equipment/sencore/tf26_cricket/graphics/sencore_tf26_cricket_full_sm_with_corrections.pdf Ratch
  5. R

    Accuracy Component Tester.

    The OP wrote "transistor tester". Perhaps he meant transistorized tester (ohmmeter). Ratch
  6. R

    Accuracy Component Tester.

    Don't think so. The resistance of a semiconductor varies with the voltage of the ohmmeter. It does not follow Ohm's law. Ratch
  7. R

    Accuracy Component Tester.

    What parameter of the transistor is the transistor tester measuring? Ratch
  8. R

    i need someone to look at this circuit before my teacher will get it

    I don't understand the "constant" power concept. Is the motor going to "starve" if it needs more power than the limits of the output supply provides? If it does not need what the supply can provide, is the extra powe going to be shunted into a heat dissipating element (resistor)? Wouldn't it...
  9. R

    New idea for oscillator

    What kind of oscillator? Sine wave, square, pulse, what? There is plenty of material in textbooks and the internet to keep you busy studying. Ratch
  10. R

    I don't understand the meaning/relevance of output impedance.

    Yes, that is true if one can only change the load impedance. But, if one is able to lower the source impedance somehow, even more power will be transferred. Consider a 1 volt source with a source and load impedance of 1 ohm each. That will transfer 1/4 watt. But if the source impedance is...
  11. R

    I don't understand the meaning/relevance of output impedance.

    You are asking two questions here. I can answer what output impedance is, but I will leave the question of how to hook up speakers to a such and so amplifier to others more in the know. Output impedance is the Thevenin impedance of the amplifier from the viewpoint of the load. It is either...
  12. R

    Saturable Capacitance

    Saturable reactors have been around for a long time. The Nazi Bastards used them extensively in Wild War II (WWII) for many of their electronic amplification needs. Compared to semiconductors, they are expensive, heavy, large, and lower performance. However, they are extremely rugged...
  13. R

    Book: Transistor Circuit Design, With Experiments, by Delton T. Horn

    Here is the way I would solve the problem. + Ratch
  14. R

    Book: Transistor Circuit Design, With Experiments, by Delton T. Horn

    Yes, there is a mistake in the book whereby Ic is not divided by beta. Also he should compute the current directly instead of deriving a formula. You could run yourself ragged by deriving thousands of formulas to thousands of problems. Whereas, if you know how to calculate the values wanted...
  15. R

    Book: Transistor Circuit Design, With Experiments, by Delton T. Horn

    I aver that it is relevant. That false factoid by the author is not a misprint or oversight. It is an indication that he does not really know some of the basics of how semiconductors operate. The OP is correct for being suspicious of the rest of the material in the book, and does well in...
  16. R

    Book: Transistor Circuit Design, With Experiments, by Delton T. Horn

    No, a BJT, FET, and a vacuum tube are all voltage-controls-current or transconductance devices. The physics of the device proves the above statement to be true. Show me something that says a transistor is current-controlled, and I will show how it is wrong. Ratch
  17. R

    Load, zener, series resistors currents

    Use the worse case of 7.3 volts and be pessimistic. To continue your calculations, the dynamic resistance of the zener at that current 5.1 volts/11.45 mA = 446 Ω. In parallel with 6800 Ω is 419 Ω. In series with 180 Ω is a total of 599 Ω the capacitor "sees". The RC time constant is 100 μF x...
  18. R

    Electrotechnic exercise (help)

    The problem is essentially balancing a Wheatstone or impedance bridge. That is sometimes hard for a newby to understand. I wanted to use loop equations like the OP did. But, you are right, it can be solved using one equation and the current source does not affect the result. Ratch
  19. R

    Electrotechnic exercise (help)

    I was wondering about the mf in the problem. Years ago I remember seeing micro-micro farads sometimes being written as mmf and being called "mickey-mikes". See this link and read paragraph #3. https://www.westfloridacomponents.com/blog/is-mf-mfd-the-same-as-uf/ . I don't remember seeing...
  20. R

    Electrotechnic exercise (help)

    Sorry I am late in helping you, but my wife and I were on vacation driving around Lake Superior last week. This is a fairly straight forward problem Don't let that voltmeter baffle you. All it tells you is the ends of branch D-F are at the same voltage when it indicates zero. In other words...
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