Discussion in 'Homework Help' started by nPab, Sep 21, 2014.

1. ### nPab Thread Starter New Member

Sep 16, 2014
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The question is to find Ve, Vc1and Vc2 in the circuit below....I have no idea whatsoever on how to begin...please explain step by step...
Thanks!

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2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Notice that Q2 base is connected directly to GND and Q1 base to 0.5V. If we assume that Vbe = 0.7V we immediately see that if we assume that Q1 is ON the Ve voltage must by equal to Vb + Veb = 0.5V + 0.7V = 1.2V and this implies that VebQ2 = 1.2V.
But you should know that |Vbe| = 1.2V cannot happen without destroying the transistor. This implies that our assumption (about Q1 is turn on) was wrong. From here we see that Q1 is cut-off (VebQ1 = 0.7V - 0.5V = 0.2V) and Q2 is in active region or in saturation. So, now we can easily find all the voltage in the circuit. Can you do it ?

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3. ### nPab Thread Starter New Member

Sep 16, 2014
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Got it! thanks loads..

4. ### KL7AJ AAC Fanatic!

Nov 4, 2008
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Just what I was gonna say.