Steps:
1. Some parts we need in this project.
2. The main steps to make the circuit.
3. Connect it to speaker and cellphone then test it.
Product list:
D718 transistor https://www.utsource.net/sch/D718
1000uf 25v capacitor https://www.utsource.net/sch/1000uf%2025v%20capacitor
4700uf 25v capacitor https://www.utsource.net/sch/4700uf%2025v%20capacitor
680ohm resistor https://www.utsource.net/sch/680ohm
474pf 100v
500k volume
More details, pls check the video on Youtube: