Can somebody tell me the calaculations of this 2 transistor circuit?

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This discussion focuses on the calculations for a two-transistor circuit involving a 2N5401 BJT. The base-emitter voltage of the 2N5401 is approximately 0.62V when it activates, leading to a constant current of 10mA through a resistor of 62 ohms. Participants emphasize the importance of understanding BJT relationships and encourage users to engage with the math rather than seeking direct answers. The conversation highlights the educational goal of the forum, promoting self-learning and problem-solving skills.

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michael1978
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can somebody tell me this circuits calculations, how come 10mA
please
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michael1978 said:
can somebody tell me this circuits calculations, how come 10mA
pleaseView attachment 218125 View attachment 218125 View attachment 218125
To start do you know how to solve for BJT circuits?
If you do know the relationship between the different ports of a BJT, then you can do what berkeman said and dive into the math.
 
Just a short hint:
When you assume a "normal" (classical) value for the voltage across the B-E path of Q6 (linear operation of Q6), it is a very simple task to get a rough estimate for the current through a resistor which is in parallel to this B-E junctiun.
 
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why you make it so difficult?
it easy, i put the problem in other forum
this is the answer for there
The base-emitter voltage of the 2N5401 Q6 is about 0.62V when it begins to turn on. When Q6 turns on it begins to cutoff Q7 so the current in R9 and Q7 is constant at 0.62V/62 ohms= 10mA.
 
michael1978 said:
why you make it so difficult?
it easy, i put the problem in other forum
this is the answer for there
The base-emitter voltage of the 2N5401 Q6 is about 0.62V when it begins to turn on. When Q6 turns on it begins to cutoff Q7 so the current in R9 and Q7 is constant at 0.62V/62 ohms= 10mA.

The goal of this forum is to share knowledge and grow the community and members, not to just blindly give you answers. In order to properly help you learn we need to know what level of experience you have, and why you are stuck on a problem. We won't spoon feed you answers if you don't respond to our questions.
 
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michael1978 said:
why you make it so difficult?
Why do you need to be given answers, when it is so easy to figure them out with our hints. You will not get very far in life with this approach, I'm afraid.

Thread is done.
 
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