Picture of Light organ
Here is how to build a light organ, an electronic device which automatically converts an audio signal (such as music) into rhythmic light effects

Step 1: Materials

Picture of Materials
1. LED lights 
2. Transistor BD233 (or similar one) 
3. 12V adapter (or battery)
4. Cable from headphones
5. Electric wires 
6. Acrylic glass 
7. Sand paper