# Please Solve this transistor circuit i dont know how to calculate all Nodes Voltages and Current

Discussion in 'Homework Help' started by nahal786, May 8, 2016.

May 8, 2016
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2. ### dl324 Distinguished Member

Mar 30, 2015
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Welcome to AAC!

Is this homework?

3. ### panic mode Senior Member

Oct 10, 2011
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of course it is...

4. ### Dodgydave AAC Fanatic!

Jun 22, 2012
5,141
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Assuming its a silicon bjt...

6v-0.7v=ReV
ReV/ 3.3k=Ie
Ie x 4.7k= RcV

Can you work these out now,?

Or do you need more time?

nahal786 likes this.
5. ### nigelwright7557 Senior Member

May 10, 2008
488
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Its a trick question.
5.3 volts at emitter gives 1.6mA
1.6mA through 4k7 gives 7.5 volts drop which you cant get as not enough volts in supply.
This means transistor is saturated and collector voltage will be 5.5 volts.

6. ### nahal786 Thread Starter New Member

May 8, 2016
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Brother Can you Explain the Formulas ? Thanks for Reply <3

7. ### nahal786 Thread Starter New Member

May 8, 2016
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@Dodgydave Bro Can You Brief Out Formulas I have Paper on 10 of May its is the Ciruit ? Can you please Brief Me ?

8. ### nahal786 Thread Starter New Member

May 8, 2016
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@Dodgydave Dear Can you Explain me it on Skype Please i will Really Very ThankFull To You <3

9. ### panic mode Senior Member

Oct 10, 2011
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yes, it is Ohms law and assumptions of simple transistor/diode model for product made from Si (most common today).

but the first answer is not complete or accurate, it was just a nuge in the right direction....
since base voltage is 6V and assumed Si BJT has about 0.7V for Vbe, emitter voltage is simply the difference
Ve=Vb-Vbe=5.3V (approx)
Now that you know Ve=5.3V, you can compute current through emitter resistor.
from Ohms law we know I=V/R
in this case Ie=Ve/Re=1.6mA or so...

For BJT we know that Ie=Ib+Ic and due (assumed) high gain Ib<<Ic we can further approximate that Ie and Ic are about the same. While usually this is the case, it is not holding here due large value of Rc and low supply voltage. i will let you work out the rest..

this is homework which means YOU need to do it, and explain your reasoning when we point your your mistakes. only then you can get explanation.... so get back to (home)work

Last edited: May 8, 2016
nahal786 likes this.
10. ### nahal786 Thread Starter New Member

May 8, 2016
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@panic mode Thanks For Your Reply Man <3 the Formula Ve = Vb -Vbe will be same for any Circuit ? and How can i Calculate Ic ? and Ib ?

11. ### panic mode Senior Member

Oct 10, 2011
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305
go back to your books or think of another career... before you can solve transistor circuits you need to have solid understanding of Ohms and Kirchoffs laws and ideal and non-ideal diode.
your teacher must have mentioned zillion tims fundamental things like

Vbe=Vb-Ve
Ie=Ib+Ic
Vf=0.7V (approx) for Si diode (which is what B-e junction is)
Vce(sat)=0.1...0.2V

if you want help, you must show your attempt and explain your reasoning.

Last edited: May 8, 2016
12. ### dl324 Distinguished Member

Mar 30, 2015
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651
You never answered my question regarding whether this was homework, but your post has been moved to Homework Help. In this forum, you need to show your work and be guided to a solution.

How do you think Ic and Ib are calculated? Do you have sufficient information to do that?

13. ### nahal786 Thread Starter New Member

May 8, 2016
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LoL :v WTF? @dl324 what do you want Man ? I Know what is Ic Current a Collector and Ib is Current at Base :3 Dont Teach me as i Joined this Forum To Just get Help For some Thing from that i am Confusing Donot Waste your time on my Thread if you dont want to help Out :3 dont try to make shit on this Thread :3

Best Regard
Nahal :v :v

14. ### crutschow Expert

Mar 14, 2008
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The base-emitter junction looks like a diode (orientation the same as the base-emitter arrow), thus in normal operation, the base-emitter voltage will be equal to the forward drop of a diode when conducting (around 0.7V).
With that knowledge and Ohm's law you can calculate all the voltages and current.
If not, then you need to study Ohm's law, and simple series and parallel circuits.

And if you think our answers are shit, then you need to go elsewhere for your answers, as we don't need the abuse.

recklessrog likes this.
15. ### nahal786 Thread Starter New Member

May 8, 2016
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Thanks Man @panic mode You save my Life <3 Thanks for Your Replyyy <3 <3

16. ### nahal786 Thread Starter New Member

May 8, 2016
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@crutschow no man the person dl243 was just Wasting my time on his shit comments that's why i said Please Dont mind Your Answer is Precious For Me Thanks Man <3

May 8, 2016
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18. ### dl324 Distinguished Member

Mar 30, 2015
3,376
651
You may find this difficult to believe, but my intention was to help you without the prospect of receiving a failing grade for cheating. No one is going to follow you through life and solve all of the problems you don't understand.

vol_ likes this.
19. ### vol_ Member

Dec 2, 2015
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Nahal are you a gangsta? I don't want to offend you. I 'm just asking and waisting my time..

And just to know i'm also a newbie in electronics and a lot of people here spend their time in this forum helping people that are starters with brilliant answers, as dl324 answer was. He gave you some clues to go on with YOUR problem.

Cheers everyone