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transistor amplifier with the common emitter configuration

malyrudy

Apr 15, 2014
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Please help me people. In school we were given homework, suggest a scheme of "amplifier common emitter configuration" and I do not know how. The scheme I have found, I even tried to calculate, but the amplifier does not amplify. Please, if someone would not be willing to help me with this, suggest resistors R1, R2, Rc, Re. I measure the input gain and output gain. If the text was a problem, I apologize for my bad English. :)
 

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KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
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Hello and welcome to Electronics Point.

I have moved your post from the Circuit Help forum to the Electronics Homework Help forum.

1. Check the polarity of your supply voltage. Also, the supply voltage source is usually shown at the right hand side, not at the top like that.

2. Your resistor values are all far too low. R1 and R2 are generally somewhere in the range 10~100 kilohms. You will need to recalculate the other resistors as well.
 

malyrudy

Apr 15, 2014
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Apr 15, 2014
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Thank you very much. Now it works. :) Now I would like to know how those values came from. I get it dialed system "trial and error" but I need to calculate them on paper black on white. :/ :)
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
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There are various ways to calculate them, but a good place to start is to choose the collector current. A typical collector current for a small-signal amplifier is a few milliamps. If there's a need for low output impedance, a higher current can be used, and if there's a need for low current consumption (battery powered device), a lower current can be used, but otherwise, a few milliamps is good.

I've actually gone through the calculations and explanations on another thread. Have a look at
https://www.electronicspoint.com/threads/voltage-or-amplitude.263452/#post-1573124 and the other posts on that thread. If you have any specific questions, feel free to ask them on this thread.
 
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