VERY URGENT HELP ABOUT COMMON-COLLECTOR AMPLIFIER??

hgmjr

Joined Jan 28, 2005
9,027
If you short the emitter of either transistor to ground (assuming the presence of a emitter resistor - not shown), then you will upset the delicate balance in bias points of the direct coupled stages which will most likely cause the output transistor to either turn-off and stay off or turn-on and stay on.

hgmjr
 

Thread Starter

dogar sahab

Joined Mar 15, 2008
116
and does it make any difference in amplification if I connect CAPACITOR on the collector side of last transistor of multistage!!!..??
 

hgmjr

Joined Jan 28, 2005
9,027
The addition of a capacitor in parallel with the emitter resistor (not shown) of the last transistor will cause the gain at the lower end of the frequency range to decrease.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,027
You are correct. I should have said that the mid-band gain would be increased and the low frequency response would remain unchanged.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,027
One thing you should keep in mind is that the a direct-coupled amplifier is very device characteristic dependent. If you replace one of the transistors with another transistor, it is highly likely that the bias settings will need to be readjusted. Another thing to keep in mind is that the amplifier's output DC operating-point will be sensitive to temperature.

hgmjr
 

Thread Starter

dogar sahab

Joined Mar 15, 2008
116
and one more thing
What would be the case when my whole Vcc(DC SUPPLY) would appear across the output???what would be the arrangement???
 

hgmjr

Joined Jan 28, 2005
9,027
And what about the effect on the output side if I connect BY-PASS CAPACITOR across emitter in both the cases????
The effect of placing bypass capacitors in parallel with the emitter resistors (not shown) on the overall frequency response of the amplifier will depend greatly on the size of the capacitors chosen for each resistor.
 
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