Circuit Analysis - Transistor Tutorial - Common Emitter Circuit- Part 3

[rave02able]

Vs={ [(4.545m)(20k)] /50 } +0.7



[rodcabzmd]

The reason why the answer for Vs is still correct though using 50k for beta is because Ic became 4.545A instead of 4.545mA. Its a Rule in division.

[shjh69fgx]

thank you man

[drjcircuits]

It should be 50 Not 50K. 50 is for beta. I'll annotate it on the video.

Dr J

[dreamer284]

@drjcircuits : Shouldn't the denominator be Rc * beta which is 2.2k * 50?

[barnamah]

at 3:53 vs<0.7 + (4.545*20k/50k) you used 50k ohms. Where does that come from? we have 50 (beta). If you ment the voltage across RB then it should have been

vs<0.7 + 4.545*20k

please clarify.

thank you

[UnderseaCaveman]

Thanks for great tutorial (I was able to follow that you mispoke and meant "50" for beta). To make more realistic, should add that Vce can not reach 0VDC (I looked up a 2n3904, and value is like 0.2VDC)....also Beta is dependent on Ic, which makes things a little trickier. I am studying the Common Emitter, and your tutorial was invaluble study... Mahalo, UC

[jharz20]

It's not 4.595mA, it's 4.545mA...

2.518V is correct...

[tainguyen01]

I'm sorry but to be too technical but i believe when you do the calculation for Vs the 4.595 value should be 4.595mA. Also, the answer should be 2.538V for Vs and not 2.518V. Anyways, thank you very much for the video good jobs.

[stephen631983]

sorry but where did the 50kohm derived from when you were calculating the VS.. i'm new to transistor calculation,,

[drjctu]

The 50 kohm at around 4:20 is when I mispoke and is not kohm but just 50. The 50 came from beta in the previous expression. Sorry for the confusion. Dr J

[NaneRulz]

Great video! Now Ifinally understand how to amplify signals with transistor. In the university we only usually use transistors in cutoff/saturation region, it's not pretty common the student who use transistors instead of opamps to amplify signals.

Thank you for spending your time with these educational vids!

[rroge5]

love your vids. what is Vbb, or Vgg, V beta i think u call it. i cant find this value in datasheets but i can find hfe. and saturation voltage.

[drjctu]

Thanks. I don't think I mention Vbb or Vgg in the video. beta is the current gain and hfe is similar to beta. Vbb is the base dc voltage and Vgg is the dc gate voltage supplied to that appropriate terminial or transistor configuration. This is similar to Vcc is the dc voltage supplied for the common emitter configuration at the collector terminal as an example. Dr J

[rroge5]

arh i see. is there anywhere where i can read more about beta and electronics?. im new to bjt type transistors and it would be cool if i knew how they work in every aspect.