Thanks, Peter. ----- Original Message ----- From: "Peter L. Peres" > There are no super simple general purpose npn amps. What signal do you > need to amplify ? Do you need voltage or current gain ? If you want > current gain a simple complementary push-pull emitter follower is all you > need. One NPN one PNP and an output cap. Also has zero quiescent current. > You also need to make sure the audio does not collapse your mcu supply. > The push-pull can be powered from the unreg rail. Most of this has actually been covered in previous posts... Audio signal 5V from Port B of AT90s2343 to a small speaker I've had good success with a circuit (basic, one-transistor, etc.) Russell suggested. My main problem was my failure to use an isolation cap to keep DC out of the speaker. This kept the cone slammed against its "stops" most of the time, preventing it from getting any decent volume. - Robert -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics