electrical current

Hello friends, first of all sorry for my bad English. I am an electrical and electronics engineering student. I have a problem in my control systems lesson project. The project is about controlling a dc motor with adjustable current and same voltage on the dc motor. The professor gave us a clue...

My project purpose is that when you hold hands with a friend the passage of electric current through a circuit is enough to turn a buzzer or the ISD1820 voice recorder speaker. My first idea it to use the circuit below as reference, but I have no idea which transistor I should use to have...