I want to amplify the current/voltage from a music source. Specifically, I want to use the varying signal to vary the light intensity of a system of LED's connected in parallel. Basically, I want to create pulsating LED's. What I'd thought of was using a sound signal from my ipod to do so. I dont think that the amplitude of current/voltage of the signal obtained from the ipod directly will be enough to observe an appreciable variation in intensity, so first I want to amplify the signal, and then use its current/voltage variations to cause the fluctuation in intensity of the LED's. I will be connecting about 5-10 LED's in parallel (with a 1K-ohm resistor in series with each LED), connect this system across a 12v DC supply and connect the amplified audio signal in series with the battery. I believe this would work, but I dont know how exactly to amplify the signal or how much to amplify it by. I know how the transistor amplifier works, but the specifics (collector voltage, ratings of transistor, if any) elude me. As always, all help is appreciated.