Reason for the use of the resistors an capacitors!?

[aj_silverthunder]

here in this schematic " https://www.flickr.com/photos/aj_silverthunder/4141615924/ " , u can see at the emitter of T1,T2 and T4, there is a capacitor and a resistor in parallel connected to ground.what would be the reason for that?,are the values are critical!

 

[svhb]

R6 and R7 are used for a DC-setpoint on the base of T3.

I just wonder, why are you keep asking if values are critical? Do you have only a very limited amount of components at hand? Do you actually to plan to build this circuit?


Stefaan

 

[aj_silverthunder]

no,i just want to learn perfectly!

 

[LvW]

here in this schematic " https://www.flickr.com/photos/aj_silverthunder/4141615924/ " , u can see at the emitter of T1,T2 and T4, there is a capacitor and a resistor in parallel connected to ground.what would be the reason for that?,are the values are critical!

As I`ve told you already in an earlier thread, it is important to know the task and the function of each component - otherwise you cannot fix a meaningful value for it.
In this case, the resistor in the emitter path establishes dc feedback to stabilize the operating point, and the parallel C takes care that this feedback will be not effevtive for frequencies above the corresponding corner frequency.

 

[sharry711]

hi
use parallel resistor for thermal stability so because this resistor decrees AC gain we use parallel capacitor with this resistor

 

[biku777]

hi..
resistor connected to emitter helps to keep the dc bias point at a fixed point through a regenerative action on the transistor...when emitter current increases coz of rise in temperature voltage drop across the resistor also increases which in turn decreases the voltage across the Vbe junction hence reducing the base current.capacitor in parallel is used as a bypass capacitor which provides a very low impendance path to the ac signal...details is given in the book microelectronics by sedra n smith...hope this will help you