I started electronics recently and I'm trying to make the most basic mp3 amplifier. First I tried to make the amp myself with reused electronic parts but I didn't succeed... Amplify speaker with 9v battery and one transistor. Do you have any recommendations about it ?
So I decided to use a LM386 because it's easier. I found a module which integrates de LM386 on dx.com for 3$. This one http://www.hamgadgets.com/LM386-AMP-MOD. But I guess I can make it myself for less and probably better/stronger.
It worked pretty well with the 9v battery if I set the gain to 50%. I read it provides up to 0.3w of audio power so it uses 0.3w/9v = 0.033a max ?
On the module it says 5 to 12v and I read that a battery provide the amps depending on the voltage and the resistance. But then I decided to try connecting it to an outlet. I retrieved an old transformer : 9V - 300mA - 2.7w. The LM386 chip on the module fastly became very hot so I disconnected it. When I tried again with the 9V battery, the led still lighted up but the sound didn't pass through.
I know home current is AC and a battery is DC but I don't fully understand it. The AC current works on cycles (is it up only during short periods ?) and DC is a horizontal straight line (in a graph). Doesn't AC provides the amperage like a battery and the 300mA value is the maximum amperage ? Why did my circuit burn ?