hi professors.

please help me in designing a class A amplifier. i want a power output of 10 watts for 8ohms load.

 

Hello,

On this page from the EDUCYPEDIA you will find some links on class A amplifiers:
http://www.educypedia.be/electronics/amplifierclasses.htm

Bertus

 

oh. yes . thanks for the link.

look at this..

http://www.elizabethtown.kctcs.edu/members/dbell/CH 09.pps

look at page 9-5 of the powerpoint file . something like this is what i want to obtain .. the cascaded amp. was put together with power amp. do you know why it's need to put them together?

 

Q1 is used as a voltage amplifier. It's output impedance in that design is 1K. While the voltage was amplified, it will not drive much of a load. The power stage are set in an emitter follower configuration. It amplifies current but no voltage. In this particular setup, the base current necessary to drive the final output Q3, is more than the output of Q1 can provide. So Q2 is added in conjunction to Q3 in a Darlington setup to amplify the current many times more, lookup Darlington for more info. The beta of the Q3 transistor is increased

C3 is a DC blocking cap allowing the coupling of the initial voltage amp to the power amp back section.