NPN CE transistor amplifier...

Hi NILADRI1321, As currently configured, your transistor is ssturated. Lower the value of the collector resistor to about 10k. This will put your collector voltage at about 9 or 10 volts. Next, lower the AC sin wave to about 10mv to ensure that the output doesn't clip. The voltage gain is about 11.3 db. GOOD LUCK!

NILADRI321, You couldn't see all of my first comment because I accidently hit "send" before I was finished. Sorry about that, I just deleted the first incomplete comment. I'll check back once in a while in case you have more questions.

Leed124.. No problem sir.. Thats ok.. Bt is it correct now?

NILADRI321, You need to give me a more precise explanation of what you mean by "correct". I noticed that you also lowered both the base resistor and the base bias voltage and the input was changed to 20mv instead of 10mv. The collector voltage is now at about 16 volts and the sinusoidal waveform appears somewhat distorted. Your voltage gain has increased to 43db (143x). The circuit configuration you have chosen to experiment with will require tweeking because it is very heavily dependent on the value of xstr beta. The collector and base resistors should be selected so that the collector voltsge is about 1/2 Vcc or about 10 volts in this case. An input sinudoid of around 10mv is a good place to start because you don't want to overdrive the Vbe junction or clip or saturate the output. When you get the opportunity, you may want to try another circuit config with feedback. I'll check back in case you have further questions. BTY, I submitted several circuits to test the EC simulator when I first purchased EC. Just select my user name and a list should show up.

Leed124 Sorry sir.. I wanted to set Input AC at 10 mv.. Bt wrong that was done 20 mv.. Btw now circuit is formed of Vce=0-10V, Vcc=20V, Vbe=685-705 mV and output resistor=34 kOhm.. Plz check if i have to do more changes..

NILADRI321, Make these final changes. If you arn't 1) change both pwr supplies to 10 volts 2) change the base resistor to 1 MEG 3) change the collector resistor to 5.6k. 4) leave your input sinusoid at 10mv 5) you will end up with the following : Vc=4.8 volts, Vbe=0,717mv, Ic=928uA, Ib=9.28uA, Av=45.7db (192.7x), DC beta=100.

Leed124 . Thank u very much sir.. I corrected the circuit as per u said and got the same results... Thank u . I shall now study the changes u made and the basic reasons.. If i get any doubt i shall ask u... 😊😊

Leed124. Sir one doubt.. Why we use a capacitor in input while coupling AC with DC..? I mean what role it plays there?

NILADRI321, Without the Capacitor the dc current will flow thru the low impedance signal generator to ground instead of thru the base of the xstr.

Ok i got.. Thankz again...

Leed124. Sir can u plz tell me why in saturation region, if we decrease I(c), I(b) is raised..?

NILADRI321, I'm not sure I understand your question. Are you referring to the circuit that you have been working on or are you asking about a xstr in general? In the general case when a xstr is in saturation, the Vce of that xstr is at around 0.2 volts or less and both Vbe and Vbc are forward biased. To achive this, Vbe must be biased on and the base current must be increased until Vce is 0.2 volts or less. Up to this point, Ic will continue to increase. After saturation is achieved, the collector load may limit any further increase in Ic. If the base voltage contues to increase, the output current will come directly from the base terminal through the forward biased BC junction ( the xstr no longer acts like a xstr with Ic = HFE * Ib)

Sir leed124..im asking aside this circuit.. While working in lab i saw in saturation region, keeping Vbe constant, as i decreased Ic, Ib increased. Bt in active region Ib is proportional to Ic... I am just searching the reason for abnormality in saturation region for last few days...

NILADRI321, Sorry, I'm not sure I have an explanation for you, but the end my last comment to you needs to be amended to say that in deep saturation the xstr Ic still follows Beta * Ib, but, Beta is no longer the active region beta, but is sometimes called the "forced beta" . It has a much lower value (approx 10 or less). So.....if you changed the value of Ic, then the req'd value of Ib would also change, but by a very different amount than what you might have expected and it may look like one is going up while the other is going down?

Yes sir..Forced Beta changes like that...

http://everycircuit.com/circuit/5705435538784256