Hello,
i can't use simple buzzer in this case, but i'm wondering how to amplify this speaker:
with as simple circuit as possible and to get as loud as possible sound???
Right now i placed some transistor, but it only increases 20-30%.. It's very quiet..
pls. help..
p.s. i'm using arduino as a source this way Arduino Playground - PCMAudio
Try "Arduino class-D amplifier" or "PAM8403" or "PAM8302" on ebay.
Leo..
The simplest speaker to use with Arduino is an amplified computer or iPod speaker. You can find battery or USB powered examples.
You could try the enclosed - it'll put a few hundred mW into an 8-ohm speaker..
regards
Allan
amp.pdf (19.6 KB)
nardev:
i can't use simple buzzer in this case, but i'm wondering how to amplify this speaker:
Put it in a bad science-fiction movie and crank up the reactor power to the matter transducer?
Its the signal that gets amplified, the speaker is "driven".
have nothing else to say...
i had those transistors.. it was ok that way.. thnx to @allanhurst
and others 
The simplest way to achieve what you require is to use a PAM8403 module. It is easy to use and provides a decent wattage of 3W.