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  1. K

    PSU repair, found strange cap, need guidance

    Look at the traces. Are the leads going to different places or are they combined on the board, such as ground? A four leaded capacitor does not strike a chord with me.
  2. K

    Switch Transformer

    The switching power supply would take the 9volt supply and switch the input from 0 to 9. The step down would take this and reduce it. So no. Remember also that the 9volts has to be directly on the transformer without a resistor. A resistor would turn it into an LR circuit which would create a...
  3. K

    sampling

    What is interesting is the RMS calculation. The equation is squared before integrating. The sin x is much different from the (sin x) squared. You then simply take the square root. The mean is based on the sinx. So to say that it is the root of the mean squared is not accurate. It's actually the...
  4. K

    Bench Test Equipment

    I found the GND to give me a ground reference with respect to the signal. I knew it would work. The heat is from the power supply I feel. One of the first things I did was to test an opamp backwards. The gain setting resistors on the noninverting input to output. It worked. The only thing is...
  5. K

    pulse width modulation

    I have since found that a third inverter added to the classic oscillator makes for a much better square wave. MP said that a two inverter oscillator migh have trouble starting up. But I found the third inverter to make the square wave better and the startup was never a problem. The output of a...
  6. K

    Latch triggering

    A diode would reduce the voltage, but I don't have a low enough current diode. So I would still need a bias resistor to ground to make the diode operate.
  7. K

    Bench Test Equipment

    I finally received the oscilloscope. It helps very much in determining pulses. I think I got a good deal as it was only $150. The thing get's very hot too. My only concern is the GND. It does not seem to do anything. Isn't it supposed to show a ground reference trace when GND is selected? Other...
  8. K

    sampling

    Yes. You can not cancel the pi.
  9. K

    analog input frequency counter with binary output.

    It's the first part you will have trouble with; a frequency measuring circuit. This is done with a differential amplifier. You compare the two frequencies, of the same phase, giving you a zero output. The phase part is the hardest. You will need to set the phase up using two generated clocks...
  10. K

    Latch triggering

    I found a good solution to my problem. I used a parallel resistor to pull down the voltage. Then I used a parallel capacitor to distort the pulse a little. This ensured that pulse did not have the duration because a capacitor tended to round the sharp edge. Now I intend to find the right...
  11. K

    Latch triggering

    Yes, the pulse is of a very short duration. I found that a series resistor won't work because of how easy it is to produce a high input. All it takes, in logic, is to produce a no voltage situation since this will reverse the PN junction.
  12. K

    Latch triggering

    I have a pulse applied to a latch when I don't want one. How can I change the pulse so that it does not trigger the latch? Would a series resistor be better than a parallel resistor? The way logic works doesn't leave me with many options. What I need is a weak source and a weak sink. That sounds...
  13. K

    Generating square wave of voltage levels 0-5V

    I operate my transistors at mid current and the beta is fine. This transistor has a beta of about 113.
  14. K

    9v dc from a 12v ac transformer

    There seems to be a misrepresentation in the voltage level. 12VAC after rectification has an average of 12V. Once you use the capacitor, the DC value becomes 17V.
  15. K

    Generating square wave of voltage levels 0-5V

    I think your PNP is biased at too low a current. It's supposed to be at 100mA.
  16. K

    Generating square wave of voltage levels 0-5V

    I think you have a voltage mismatch. You have a an emitter follower that shares the same voltage as the collector of the PNP. Suppose you have a large signal at the collector of the PNP. This is going to make the VGS behave strangely. I think the bias is right, but a signal is not going to...
  17. K

    energy bands

    Current can come from either of two energy bands. What is the difference between current at one energy band and the current at the other energy band? They both consume the same amount of power, I believe. This is an open question to anyone that has a theory.
  18. K

    transistors

    Re division is an inherent property of the transistor and the signal is divided by it. It has nothing to do with source resistance. Could somebody corroborate the bidirectional re?
  19. K

    How to increase reactance in a coil of few turns?

    An autotransformer is easy to calculate for the current and voltage. An isolation transformer is done a little differently. You must have enough reactance to limit the current in the primary. The secondary will also have to be able to handle the current. Try this, breakdown the sine wave into 16...
  20. K

    transistors

    I wanted to know if someone could corroborate this point in theory. When a signal is applied to the emitter of a transistor, it is divided by re. When the signal is applied to the base, it divides in the other direction re. This makes re division bidirectional. Am I correct about this assumption?
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