you calculated the AC equivalent resistance between base to emitter. re, to be 52 ohms. Why isn't the AC equivalent resistance between collector and emitter not ever calculated in such cases? Won't that affect the circuit as well?
Yes the AC equivalent resistance from collector to emitter can be calculated. In fact this AC resistance is called the output resistance of the transistor designated by r_o. It is dependent on the collector current, collector to emitter voltage and a phenomena called early effect cased by collector to base junction depletion width modulation. You can calculate this resistance at a particular collector current by using the formula r_o = (V_A + Vce)/Ic. V_A here is the early voltage typically around 80~100V for small signal transistors. The reason it is neglected most of the time is its value is quite large. In the circuit shown in the video its value is around 200kΩ which will not have much effect. If you want re-do the calculation with r_o = 200kΩ included and see what effect it will have on the gain, input and output resistance of the amplifier shown in the video.
good job Sir keep going
you calculated the AC equivalent resistance between base to emitter. re, to be 52 ohms. Why isn't the AC equivalent resistance between collector and emitter not ever calculated in such cases? Won't that affect the circuit as well?
Yes the AC equivalent resistance from collector to emitter can be calculated. In fact this AC resistance is called the output resistance of the transistor designated by r_o. It is dependent on the collector current, collector to emitter voltage and a phenomena called early effect cased by collector to base junction depletion width modulation. You can calculate this resistance at a particular collector current by using the formula r_o = (V_A + Vce)/Ic. V_A here is the early voltage typically around 80~100V for small signal transistors. The reason it is neglected most of the time is its value is quite large. In the circuit shown in the video its value is around 200kΩ which will not have much effect. If you want re-do the calculation with r_o = 200kΩ included and see what effect it will have on the gain, input and output resistance of the amplifier shown in the video.
Nice boy. Nice boy.