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  1. R

    Voltages - continuation of the discussion

    After an infinitesimal time and an infinite current spike, the voltage at the junction of c2 and c4 will be 4 volts. The voltage at the junction of c3 and c4 will be 2 volts. The charge imbalance is Q = C E for every capacitor. And the point is? Ratch
  2. R

    Voltages - continuation of the discussion

    Without any resistance in the circuit, the current will be at an infinite value for an infinitesimal amount of time to fully energize the capacitors. I would include a little resistance in the voltage source so that the calculations don't "blow up". Ratch
  3. R

    Voltages

    You have 5 loops and 4 nodes in that circuit, therefore use node analysis to figure out the voltage at each node. The voltage difference between each node is the voltage across each capacitor connecting any two nodes. You will have 4 differential equations and 4 unknowns. You can also try to...
  4. R

    Pnp bjt

    I try to keep up with individual components, but not every packaged circuit that can be found on the Autobahn Speedway of new and hybrid products. I know it is useless to try to change technical slang, but at least I can flag it. Too many folks are talking technical trash (TTT) these days. Ratch
  5. R

    Pnp bjt

    Appears to me that the name they gave that component is a misnomer. It is an interface circuit that makes use of transistors and resistors, but it is not a special transistor that operates on digital principles like the name implies. The link also says that it converts voltage to current...
  6. R

    Pnp bjt

    What on Earth is a digital transistor? A transistor is a analog device that can be operated in saturated mode ( switch ON), cutoff mode (switch OFF), or active mode for signal amplification. Depending on the values of R3, R4, and the impedance of the load, the PNP transistor shown can be in...
  7. R

    Voltage source and current source on source electrode of MOSFET?

    Any time you have a current source in series with a voltage source, you can ignore the voltage source because the current source will output any voltage necessary to make its current happen. Putting voltage sources in series will just cause the current source to increase or decrease its...
  8. R

    Capacitance of capacitors

    The circuit has 4 nodes and 5 loops. You can use either loop or node analysis to find the voltages, currents, and the impedance of the circuit. You will have to solve 4 or 5 equations for 4 or 5 unknowns. Once you know the impedance, you can find the resultant capacitance. Later edit...
  9. R

    Info for 2N3904 and 2N3906

    It would be a good idea to first learn how a junction diode (JD) works before trying to understand how a bipolar junction transistor (BJT) works. Although you cannot make a transistor with off the shelf JDs, many of the same JD principles are in effect for BJT operation. You have two...
  10. R

    Thevenin-Norton conversion

    1. Use loop, node, or branch analysis to find the voltages and currents. 2. Determine the voltage across the open terminals a-b. That will be the Thevenin voltage. Then short terminals a-b and determine the current existing in the short. That will be the Norton current. Divide the voltage...
  11. R

    Best value resistor to discharge .45 F cap?

    Here is the dissipation of an 80 ohm resistor plotted against time. Notice that after 10 seconds, it is still dissipating slightly less that 3 watts. Shown also is the dissipation equation. Ratch
  12. R

    Positively charged "holes"?

    A field is a spatial distribution of a quantity. In the case of an electric field (EF), the quantity is the force exerted on a charged particle (electron, hole, positron, etc). A EF has a strength and direction, not a polarity. It is charged particles that have polarity. An EF can be...
  13. R

    Series Transistor Voltage Regulator

    That is an indefinite answer. The internal resistance of the voltage regulator (transistor?) is always present and always causes some voltage loss. Specifically, if the input voltage rises, then both the voltage of the transistor and the load will tend to rise proportionately. That will be...
  14. R

    Series Transistor Voltage Regulator

    Does that mean that you agree that the circuit contains negative feedback? You need to specify what causes the load current to increase. I already showed that if the current increase is caused by a reduction in load resistance, then the output voltage does not change. If the increase in load...
  15. R

    Series Transistor Voltage Regulator

    Yes, you are correct. I was only considering an ohmic load. Upon further consideration, I think it is useless to ask how the regulator works if the load resistance changes. If the resistance doubles or is halved, the current is halved or doubled, and the IR output voltage remains the same...
  16. R

    Series Transistor Voltage Regulator

    I believe the OP's question and concern was addressed and answered. Any further discussion is for the rest of the group's edification and benefit. I wish that others would participate in this dialog and offer opinions based on fact about which of us is correct. Ratch
  17. R

    Series Transistor Voltage Regulator

    Irrelevant. The zener operates in its breakdown region no matter whether it is fed with a voltage or current source. The Vz vs Iz curve shows an almost vertical slope, denoting a nearly constant voltage despite large current changes. Even batteries or power supplies change voltage somewhat...
  18. R

    Series Transistor Voltage Regulator

    No one says that a single uncompensated zener is a perfect voltage regulator. What are we talking about here, a few millivolts? That circuit is a regulator, not a voltage standard. To a first order, a zener keeps the voltage constant within its current range. Nothing is perfect in this...
  19. R

    Series Transistor Voltage Regulator

    Why impossible? If the load resistance should rise, perhaps from a temperature increase, then the output voltage will rise unless the load current is reduced. I explained how that happens in my last post. Why would that happen? The input voltage source will just absorb that extra zener...
  20. R

    Series Transistor Voltage Regulator

    What does "HND atm" mean? Expand your acronyms at least once so folks know what you are talking about. Better yet, if it does not pertain to the problem, don't mention it. If Vin changes, the constant current operation of the collector won't be affected very much. The collector voltage can...
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