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  1. R

    Basic Physics Question

    Your question leads me to believe that you do not really, really know what voltage is. Voltage is the energy density of a quantity of charge. Like charges don't get along too well together, so it takes a certain amount of energy to gather like charges into a certain amount of volume. It takes...
  2. R

    Basic Physics Question

    The net charge does not increase or decrease in a closed system according to the Law of Charge Conservation. KCL states that the rate of charge flow into a point is equal to the rate of charge flow from a point. KCL is a consequence of the Charge Conservation Law. The Law of Energy...
  3. R

    Resistor values.

    You might want to look at post #2 of this thread. http://www.electro-tech-online.com/threads/bullet-proof.146490/#post-1240701 Ratch
  4. R

    Opamp help

    Which gain? The gain of v1 or v2? Incremental gain or static gain? r1, r2, and v1 sets the voltage at the + and - terminals of the op-amp. Then is a simple matter of solving a node equation as shown below. Ratch
  5. R

    cant find the tranfer function of 2nd order lpf

    R3 is very important to the operation of the circuit because it provides a conduction path to the negative input of the op-amp, and therefore negative feedback. Its value is not important because it will probably be insignificant compared to the input resistance of terminal 2 of the op-amp...
  6. R

    Watchout for this everyone

    From Russia, with love. Ratch
  7. R

    Watchout for this everyone

    To the ineffable all, http://www.electronicproducts.com/Computer_Peripherals/Communication_Peripherals/Booby_trapped_USB_stick_fries_your_computer_hardware.aspx Ratch
  8. R

    Transformers and bridge rectifiers [question]

    Bridge rectifiers make possible full-wave rectification without a center tapped transformer, and only require half the turns ratio. In the above circuit, a two diode full-wave rectifier would require a 64 volt center-tap transformer Laminated cores reduce eddy currents. Ratch
  9. R

    Bucking voltages

    You get a "bucking" voltage when you energize a capacitor. As the charge builds up on one plate, it depletes on the opposite plate. This charge imbalance produces a voltage across the capacitor which opposes the applied voltage, and reduces the energizing current caused by the applied voltage...
  10. R

    Minimize logic expression for each segment in 7 segment LED

    You can try a program I wrote to check logic calculations. Expand the zip file into a temporary file and read the documentation. Take your K-map answer and plug it in. My program will give you the minterms. If the minterms match what you used on your K-map, then your reduction is correct...
  11. R

    z parameters applications

    Nope. Z parameters have been around since the year one. Ratch
  12. R

    Variable capacitor

    Perhaps this might be of assistance to you. http://www.falstad.com/circuit/e-capmult.html Ratch
  13. R

    z parameters applications

    Strange, I Googled for z-parameters and got a quarter million hits. This is typical. https://en.wikipedia.org/wiki/Impedance_parameters Ratch
  14. R

    BJT current gain

    What is your confusion? The schematic layout is your own, and my description of the calculations reference your component designations. Start from my first sentence explanation of the current (amperage) value, and let me know what you do not understand. Stop at the first point of confusion...
  15. R

    BJT current gain

    Well, let's see. Hmmm. Just about all the Iin will be present in the Q1 base-emitter-C1 path, because that conduction path has a very low impedance compared to the 1k of the base resistor. Q1 will betatize that current and send it through R3, because R3 has a much lower impedance than R7||R8...
  16. R

    PN junction

    You really should read up on junction diodes before you ask anyone to explain how they work. There is lots of information about this subject. To get you started, you must realize that junction diodes work on the diffusion principle instead of using an electric field to move charge carriers...
  17. R

    Find the output voltage and the input impedance

    Your answer is wrong. You are losing 250 microamps of current from the 2.5 volts going through R3. That has to be made up from extra current present in R4. That will increase the voltage across R4 by 3.75 volts, making the correct answer 10 - 1.5 Vin. You can also calculate the correct...
  18. R

    Better understanding of Electricity.

    As I stated before, since charge flow means current, why add an extra word onto current to make it into charge flow flow? Ratch
  19. R

    Better understanding of Electricity.

    Question asked, question answered. Just because some of us don't do electronics for a living doesn't make us laypeople. The amount of specialized knowledge we possess elevates us above the person who is clueless as to how electronics work. You can find people of all degrees of electrical...
  20. R

    Better understanding of Electricity.

    He grasped what the video was about and offered an opinion on it, didn't he? Therefore, I assume he knows what I am talking about. Besides, it was the video presenter, not the OP who said "current flow" It is like I said, it is a slang term. Slang is usually not precisely descriptive and...
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