hello im a beginner here. can you guys please help me build a simple audio amp using the following

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.

my source is a frequency generator using 555timer ic with potentiometer varying the frequency

my desired output is something like this

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 tried both circuits but it wont work.

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

many thanks in advance.

 

You can connect the piezo direct to the '555 output, but note that they only work well at a particular frequency.
You can also connect the speaker to the '555 output via a resistor - I would suggest 33 to 100 Ohms - that should make an audible noise (not very loud).
If neither of these make any audible sound then the problem is with the '555 circuit and in this case please show us a schematic of how you are using the '555.

Either of the circuits linked to will work - they are not going to produce stadium filling volume, but they should definitely be audible.
If you are using the LM555 it can supply quite large currents so adding the single transistor won't add much so is probably not worth bothering with.

 

thank you sir for the fast response, the speaker or piezo produces sounds audible enough. but i hope to make it a little louder more by using simple components like transistor (active device) and a few resistor.

 

Which '555 chip are you using (i.e. what letters come before the '555' on the chip)?

 

Which '555 chip are you using (i.e. what letters come before the '555' on the chip)?

sir albert the top portion of the 555 ic was faded already .... but i remember the max current output is around 20- 25ma.

 

Did you try the circuit below? You need 2 extra transistors BC337 & BC327. You can use bc548B as T1.


It is from the link here..... There are more audio amps at the bottom of the page with explanations.

Allen

 

something like this https://bryanduxbury

it does not look like a failure unless you use PNP instead of NPN or messup the pinout using gain 1 collector to load instead emitter to load
'huck - 10mA transistor ???? (5-.7)/104=.04 , 40mA×20=800mA starting current (the metal package can keep it a live for instant) use 3x2N2222 in parallel or higher power or mosfet or reduce your base current 160× e.g. use (5-.5)/5mA=900 - 4ohm speaker ×20 18kΩ