please help transistor amplifier

michael1978

so result is correct 66.6, for ib like this is formula for current Ir5-Ir4? is not the same for ir4 and ir5 they are in serie ir4 and ir5
but Jony you told Ve to be 1v why is now Ve 0.4V?
thnx for reply

michael1978

thnx for reply
]so result is correct 66.6, or voltage gain is 66.6, if so 66.6*2Mv=133mv again the result is not corrcect
for ib like this is formula for current Ir5-Ir4? is not the same for ir4 and ir5 they are in serie ir4 and ir5
but Jony you told Ve to be 1v why is now Ve 0.4V?
thnx for reply[/QUOTE]
thnx for reply

michael1978

thnx for reply[/QUOTE]

hi Jony, can you answer me please

Jony130

66 is a BJT current gain, not a amplifier voltage gain.
So in order to make this circuit work properly. You need change the BJT that you use in your simulation program. You need to find the BJT with Hfe > 300 in your simulation.

michael1978

ah 66 is curent gain, so you mean to change type of transistor, but is possible for you to tell me any type of transistor wich work, because there are a lot of type of transistor, and somebody he tell me one type of transistor but that transistor dont exist in my list of transistors
and yes Jony if you can tell me, i try to find self soms but i cant find it, that is the problem
thnx for reply

Jony130

BC548C
What simulation program do yo use ?

michael1978

o joney i dont have, i have bc548A but not BC548C, i use B2 Spice A/V

michael1978

hey Jony i try with bc548A, and i get voltage gain of 84mv is this correct?

Jony130

Use BC547C

michael1978

yes Joney i have that type i change, and now voltage gain is 94mv is correct now?

Jony130

Well first you need to learn how to use the simulation program.
I use B2 Spice V5 and as a BJT use BC547C. And AC sweep analysis show that voltage gain is equal to 50.1V/V
For 20mV at input I get 1V at output.

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michael1978

but this was disegn for 10v battery not 12v

Jony130

Well for Vcc = 10V the voltage gain is equal to 46V/V (0.9V at output for 20mV at input) because we don't included RL in our calculations when we solve for Re2.

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michael1978

my circuit look like this

Jony130

If so, your voltage gain is equal to 46V/V

michael1978

my circuit look like this , the voltage gain is correct almost the same like yours, but metter gain is not correct, WHY GAIN METTER NOT CORRECT

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michael1978

yes almost 2Mv*46=92MV my 94MV