The transistors BC 548(T2), BC 188(T1), and capacitor 0.01(C1) muF makes an oscillation circuit and makes a continues vibration on the speaker coil. The frequency of the vibration is depended on the resistance given to the base of T2. This vibration becomes a sound of corresponding frequency. Through the switches the resistance is given in particular value and this creates different sounds.Here transistor is used for oscillation.