How to calculate the amplification of a common basis stage

G

Geir Klemetsen

Guest
I know all the values, included the hfe for T1. And it's the voltage
amplification I want to find.
I'm loking for a formula to calculate it (not measure the input and
output).


Here is the schematic:
(Best seen using fixed font Eg. Courier)

+Ucc
.-----------------o------------o
| |
| |
.-. .-.
| |R1 | |R3
| | | |
'-' '-'
| | || V~out
| o-----||-----o
| | ||
| | C2
| |/
.----o--------------|| T1
| | |>
| | |
| | | || V~in
| | o-----||-----o
| | | ||
| .-. .-. C3
C1 --- | |R2 | |R4
--- | | | |
| '-' '-'
| | |
| | |
'----o-----------------'
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
 
"Geir Klemetsen" <regeir@N0ZPÁM.start.no> wrote in message
news:bKaub.7296$mf2.101487@news4.e.nsc.no...
I know all the values, included the hfe for T1. And it's the voltage
amplification I want to find.
I'm loking for a formula to calculate it (not measure the input and
output).


Here is the schematic:
(Best seen using fixed font Eg. Courier)

+Ucc
.-----------------o------------o
| |
| |
.-. .-.
| |R1 | |R3
| | | |
'-' '-'
| | || V~out
| o-----||-----o
| | ||
| | C2
| |/
.----o--------------|| T1
| | |
| | |
| | | || V~in
| | o-----||-----o
| | | ||
| .-. .-. C3
C1 --- | |R2 | |R4
--- | | | |
| '-' '-'
| | |
| | |
'----o-----------------'
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
Click to expand...
Try this: http://www.tpub.com/content/neets/14179/css/14179_86.htm
 
"Baphomet" <fandaDEATH2SPAMMERS@catskill.net> wrote in message
news:vrihpj6lr2cg42@corp.supernews.com...
"Geir Klemetsen" <regeir@N0ZPÁM.start.no> wrote in message
news:bKaub.7296$mf2.101487@news4.e.nsc.no...
I know all the values, included the hfe for T1. And it's the voltage
amplification I want to find.
I'm loking for a formula to calculate it (not measure the input and
output).


Here is the schematic:
(Best seen using fixed font Eg. Courier)

+Ucc
.-----------------o------------o
| |
| |
.-. .-.
| |R1 | |R3
| | | |
'-' '-'
| | || V~out
| o-----||-----o
| | ||
| | C2
| |/
.----o--------------|| T1
| | |
| | |
| | | || V~in
| | o-----||-----o
| | | ||
| .-. .-. C3
C1 --- | |R2 | |R4
--- | | | |
| '-' '-'
| | |
| | |
'----o-----------------'
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Try this: http://www.tpub.com/content/neets/14179/css/14179_86.htm
Click to expand...
I should have added Google [ calculate gain common base transistor ]
 
On Mon, 17 Nov 2003 22:13:35 +0100, "Geir Klemetsen"
<regeir@N0ZPÁM.start.no> wrote:

I know all the values, included the hfe for T1. And it's the voltage
amplification I want to find.
I'm loking for a formula to calculate it (not measure the input and
output).


Here is the schematic:
(Best seen using fixed font Eg. Courier)

+Ucc
.-----------------o------------o
| |
| |
.-. .-.
| |R1 | |R3
| | | |
'-' '-'
| | || V~out
| o-----||-----o
| | ||
| | C2
| |/
.----o--------------|| T1
| | |
| | |
| | | || V~in
| | o-----||-----o
| | | ||
| .-. .-. C3
C1 --- | |R2 | |R4
--- | | | |
| '-' '-'
| | |
| | |
'----o-----------------'
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
Click to expand...

Assuming all the caps are big enough, Vin drives the emitter
resistance of T1 (which should actually be Q1... 'T' means
'transformer') , whose small-signal impedance is about re = 26/Ie, Ie
being emitter DC current in milliamperes. So we now know the AC
current into the emitter (factor in a bit of current lost into R4, if
you're compulsive.) Now most of that (we lose a bit to the base from
finite beta) shoots out the collector into R3 and becomes the AC
voltage output.

OK?

John
 
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