can you guys please help me build a simple transistor audio amp like the following

https://bryanduxbury.com/2012/01/20/one-transistor-audio-amplifier-for-arduino-projects/

or this

http://www.next.gr/circuits/buzzer-interfacing-with-pic16f877a-slicker-l48286.html

i try the following circuit but there is no output.

my only available materials are

bc 548b transistor
4 ohm 0.5w speaker or d24mm Piezo Transducer
i know i need to consult the datasheet to solve for the base collector emitter parameters but i dont know how.
http://www.rectron.com/data_sheets/bc546-547-548.pdf

my source is a frequency generator using 555timer ic with potentiometer varying the frequency
pin output from ic is around 20 -25ma max

my desired output is something like this


hoping someone can teach me how to make one and how to compute one

many thanks in advance.

 

Connect the 555 to the spkr via 10u

 

As Colin says. A single transistor stage with a BC548B won't give you any more output volume.

 

As Colin says. A single transistor stage with a BC548B won't give you any more output volume.
It will give you LESS.