This circuit has been bothering me for a long time, hope someone can help me.
At present, I only know that the voltage source of 20V can be ignored because it is an NPN transistor. The second picture is the limit I can do, but I still don't know the values of those components.
I'm not sure about the value of the bottom resistor, is it still 1KΩ?
Ainhoa Posted on August 28, 2020
For this circuit, the lower resistance is 1KΩ. Assuming that the transistor is in a state of conduction and amplification, the Ube of the transistor is 0.6V, then the Ube, Rb and 5.6V of the transistor can be equivalent to a voltage of 5V, and the internal resistance is Rb/(1+β )Ω power supply, in series with the 1KΩ below.
Xaviera Posted on August 28, 2020
Thevenin is used in linear circuits. Diodes and transistors are nonlinear devices, so you cannot use Thevenin's theorem here. You can make a small signal model circuit as a linear replacement version of this circuit, and then you can use Thevenin. You can't ignore the 20V voltage source because of the influence of the collector current.
Matia Posted on August 28, 2020
Use small signal equivalent circuit to solve.
