φιλε Βαγγελη αυτα βρηκα απο το μανουαλ
c) PWM VOLUME CONTROL
The discrete volume control makes use of 4 Transistors 7505, 7506, 7507 & 7508 (ON4986 or selected BC557B) and PWM
control signal from μP. For good performance transistors for the left and right channels should be paired for gain
characteristics.