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NEED HELP REGARDING BJT TRANSISTOR CIRCUITS.

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agnivesh

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Hi there

Right now I'm trying to learn BJT transistor working. I read some books on basics of transistors and DC biasing circuits and tried to run simulated transistor circuits on electronis workbench, but couldn't make a single working circuit. ( I can't figure out which beta(FE) to chose for fixed baised circuit). i.e, I'm confused which parameters I'll have beforehand and which parameters are to calculated using data sheet and design specifications.

I want to know the basic approach for designing transistor circuits, how to use data sheet in circuit design and what are the initial design parameters one must have before starting circuit design.
 

first u have to know what are u going to do with your circuit.
if u need amplifie a signal you have to decide the output amplitude, that gives a excursion and help to decide the polarization point.
 

The bias circuit should have feedback so that the differences in beta between different transistors do not affect the bias current too much.

First decide what emitter current you want. The data sheet will then give an average beta for this condition.

The classical method is to use a resistor between emitter and ground. Have the value to drop about 5 to 10 percent of the power supply across it. Have a voltage divider between the supply and ground for connecting to the base. Have the tap point be about 0.65 V higher than the emitter voltage. Set the values to draw about 10 times the current from the supply as the base current.
 

on man, you should start from cmos, bjt, too outdated, school teach cmos now
 

What kind of circuit u want to design. Accordingly just surf on web & u will find lot of info. Theen if required we can help u for specific circuit.
 

hi dear,
please found the attached file i hope it will help you
 

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