Figure 1.1

Create a circuit where the negative sides of the both LEDs is connected to each other and connected to the collector pin of the transistor where the positive side of the battery is connected and both emitter pins of the transistors are connected to each other where the negative side of the battery is connected.

Figure 1.2

Connect the positive of the audio jack to the base of one transistor, the negative side to the collector pin and the ground to the emitter pin.

Figure 1.3

Connect the positive wire of the battery to the positive leg of the led and the negative wire to the emitter leg of the other transistor.

Figure 1.4

Connect the audio jack to a splitter. Connect one wire to a cellular phone and the other to a computer before playing the music.