COllector of Q3 is (246/36)*0.7 V..
Real (210/36+1)*0.629V+ibQ1*210kOhm.
...but somehow C1 increases gain, don't understand how
General feedback is replaced by two feedbacks.

 

what is GIGO?

Garbage In, Garbage Out

Used current source so high impedance and high open loop gain

How can you have a high open loop gain if the Q2 will kill all off it? Due to its low input impedance.

 

but somehow C1 increases gain, don't understand how

Here you have an opamp "equivalent" version of a Bordodynov amplifier.



And for a AC signal treat C1 as a "short circuit".

 

It is not entirely correct to replace the second transistor with an opamp. Everything is more complicated.
The emitter of the second transistor is an output of the emitter follower.

 

Garbage In, Garbage Out


How can you have a high open loop gain if the Q2 will kill all off it? Due to its low input impedance.

Add emitter resistor on Q2?

Today is bad day for you? You confuse me today with 0 help
Post link to circuit

 

Here you have an opamp "equivalent" version of a Bordodynov amplifier.

View attachment 178792

And for a AC signal treat C1 as a "short circuit".

why no resistor on positive input on U3 but resistor on U2?

Positive input of U3 should be 1.08V? which is input at base of Q3?

 

See

 

See
View attachment 178815

don't understand unfortunately...bandwidth to see?

Whats dashed line? and what is the right circuit for?

 

I took your circuit and showed what the gain of each cascade and what the resulting gain and the results of this calculation coincided with the results of Spice. Some have suggested that the current generator is of little use and there will be a small gain. I can immediately say that if the current generator is replaced by a resistor, then the gain of the first stage will decrease by about 15 times.
My circuit on three transistors with multi-loop feedback has a gain of more than a thousand and almost limit output amplitude without distortion.
...
Why would there be no oscillation?
In my scheme, I did not use strong feedback. I broke the gain in two. Reduced gain using feedback using emitter resistors. The maximum number of stages covered by the feedback is 2. Everything increases the stability of the amplifier. I also applied a power filter.

 

I took your circuit and showed what the gain of each cascade and what the resulting gain and the results of this calculation coincided with the results of Spice. Some have suggested that the current generator is of little use and there will be a small gain. I can immediately say that if the current generator is replaced by a resistor, then the gain of the first stage will decrease by about 15 times.
My circuit on three transistors with multi-loop feedback has a gain of more than a thousand and almost limit output amplitude without distortion.
...
Why would there be no oscillation?
In my scheme, I did not use strong feedback. I broke the gain in two. Reduced gain using feedback using emitter resistors. The maximum number of stages covered by the feedback is 2. Everything increases the stability of the amplifier. I also applied a power filter.

Thank you...Will build 3 stage circuit today and use double feedback and see...Jony is having a bad day unfortunately

 

Hi,

what is GIGO?

The meaning I'm aware of is: Garbage In = Garbage Out.

 

There is also feedback in the output stage (emitter resistor). This emitter resistor increases the base voltage of the third transistor, and also reduces the gain of the third transistor, which reduces the gain of the last two stages and this increases their stability. It also reduces distortion without the common feedback of the last stage.
Ps. Do not add a 100 pF capacitor to the output. This is not a schema element.

 

Seriously, if you want to understand BJTs, start here:

Title: Understanding Basic Electronics, 1st Ed.
Publisher: The American Radio Relay League
ISBN: 0-87259-398-3

 

Seriously, if you want to understand BJTs, start here:

Title: Understanding Basic Electronics, 1st Ed.
Publisher: The American Radio Relay League
ISBN: 0-87259-398-3

Thank you...MrChips suggested before

Read online that book is very basic (I am basic and for sure there's something in to learn)...Please if you have the book can you post a bjt circuit in it?

It's "cheap" $26..can get it today but have some basic books already

Please post circuit if you have

 

Quick question : still reading, know will understand it better later in chapter but anyways.......

How to get 1mA through R? don't we need to know Vs? (voltage at source?)

 

See

 

View attachment 178784 View attachment 178783 It is quite possible to use three stages of a circuit with a common emitter, if we introduce into them several negative feedbacks. As a bonus, this is a more stable gain and reduced distortion. Here is an example of such an amplifier:

Please how to calculate gain? dont understand how C1 increases gain..Negative feedback should reduce gain, no?

 

COllector of Q3 is (246/36)*0.7 V..
Real (210/36+1)*0.629V+ibQ1*210kOhm.
...but somehow C1 increases gain, don't understand how
General feedback is replaced by two feedbacks.

Please how to calculate gain...was trying to do similar circuit but with 2 npn and 1 pnp then realized I don't know how to get the 1000 gain

 

See
Do not locate the outlet close to the entrance. Otherwise there will be oscillation. The gain is large at frequencies of the order of megahertz and there is practically no phase shift. Therefore, for oscillation, a small enough capacitance between the input and output...

 

See
View attachment 178874Do not locate the outlet close to the entrance. Otherwise there will be oscillation. The gain is large at frequencies of the order of megahertz and there is practically no phase shift. Therefore, for oscillation, a small enough capacitance between the input and output...

lol..want to do it myself..How to calculate the gain of the nice circuit?

and want to do npn then pnp then npn..Please how to calculate gain so I know how to choose resistor values