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    How a BJT Transistor works (base current version)

    In a diffusion diode, current is controlled a little differently than in a resistor. The diode current is controlled by diffusion. This is caused by uneven and different doping between the P-N slabs. The voltage across the diode controls the diffusion by opposing the back-voltage caused by...
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    Obtaining a transfer function using two-port network analysis

    You can find the transfer function by loop analysis, node analysis, branch analysis, or the potentiometer method. Do you know how to do any of those? Usually the potentiometer method is the easiest. If R1=R2 and C1=C2, the analysis is greatly simplified. Ratch
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    How a BJT Transistor works (base current version)

    I looked over your calculations and found only a minor arithmetic error, in that ic should be 0.00600785, not 0.006078. That makes the amplification range from -10.8338 to -12.4135. I plotted the gain vs beta below. As you can see the gain does not change much after beta > 200. I also...
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    How a BJT Transistor works (base current version)

    I might also mention the current mirror, which depends on Vbe vs Ic. However, I am wary of models and experiments which can be misinterpreted. And, all those applications you listed above are circuits, not the device only. As for a BJT, the diffusion diode action brings the charges into the...
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    How a BJT Transistor works (base current version)

    It should show correlation. It won't show causation because the base currents will be the same in both cases, and it could be said that current is controlling the transistor. This demonstrates that control cannot be determined by experimenting, models, or simulations. One has to get involved...
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    How a BJT Transistor works (base current version)

    To All, I got an idea. I don't have an electrolab, but someone here does. Why not take a common transistor like a 2N3904 or something similar. Hook it up to operate in the active region without any resistors and bias the collector with some midrange voltage. Then carefully increase the Vbe...
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    How a BJT Transistor works (base current version)

    Claude, "I looked through it, and they did mention the term w/o really defining it. Please explain "uncovered" vs. "covered" charges." My apology. The page number should be 17, not 27. "But I said when hole moves through p region it is majority, as are electrons in n region. When they cross...
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    How a BJT Transistor works (base current version)

    Claude, "Diodes/bjt are used in circuits, and the internal physics is best examined under real world circuit conditions. The resistor is all important since a battery across a naked diode is certain doom for said diode." "0.8 volts!!! Back in the mid 70's I tried doing just that. The result...
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    How a BJT Transistor works (base current version)

    Look at page 27 of this link. http://users.ece.gatech.edu/mleach/ece3040/notes/chap01.pdf No it doesn't. The Vbe reduces the back-voltage and allows a greater value of Ic to exist due to diffusion. When an electron moves from the N-slab into the P-slab, it is no longer a majority carrier...
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    How a BJT Transistor works (base current version)

    The bias circuit may or may not be be powered by the Vcc supply. It could be powered by its own power supply. That point is irrelevant. If you insert a external resistor in series with a PN junction like the base-emitter slabs, then you are looking at a circuit, and not just the junction...
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    How a BJT Transistor works (base current version)

    The collector current Ic will be present at any small Vbe voltage above zero, but it becomes significant at around 0.6 to 0.8 volts due to the exponential relationship of Vbe to Ic. Many folks use 0.7 volts as a approximation of what the Vbe is in the active region of the transistor. Claude...
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    resultant waveform

    Yes, I see that now. The voltage triangle, power triangle, and impedance triangle will all have the same proportions because the same current exists in all the components. Ratch
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    How a BJT Transistor works (base current version)

    Claude, You are still ignoring the physics of the BJT. The Vbe decreases the back-voltage caused by the uncovered charges due to diffusion, and allows more Ic charge flow driven by diffusion to take place until a new equilibrium is established. That proves Vbe is the control of Ic in a BJT in...
  14. R

    resultant waveform

    To All, Upon reviewing the above solutions, I think we are all wrong. The max voltages are, I believe, are 0-peak values, so the RMS values are 7/sqrt(2) = 4.95 and 11/sqrt(2) = 7.78 . It cannot be said that the resistance voltage is 0.8 of the apparent voltage "s", because 0.8 is the power...
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    resultant waveform

    After returning from an absence, I agree with your solution. I think I needed to get away for awhile. Ratch
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    Gone

    I will be absent from this forum for about a week. Ratch
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    resultant waveform

    Well, let's see. The power triangle ratio is 1, 0.8, and 0.6. That makes the first voltage supplying 3/4 of the power that the second voltage does. Since power is proportional to the square of the voltage, we can find the second voltage to be 8.08 by solving the equation 7^2/ V^2 = 3/4...
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    How a BJT Transistor works (base current version)

    I studied up a little about batteries from some chemistry textbooks. It appears that only the cations and anions travel through the electrolyte, but no electrons. Electron transfer is caused by reduction at the cathode and oxidation at the anode, but the electrons only travel along the...
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    Power Regulation Strategy

    I would use a variac (variable voltage transformer) or something else to lower the AC. Adjust the AC variac voltage until it is sufficient to power the load. The idea is to let the load use most of the power so the regulators don't have to dissipate such a heavy load. A heavy current load...
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    How a BJT Transistor works (base current version)

    Well, we have had this emitter current discussion before in another thread in another forum. I can't speak for Lvw and I have never taught a class. But, I will paint myself into a corner by saying that Vbe controls both Ie and Ic. Ie and Ic are in series with each other, so if one changes...
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