SYSTEM / Electrical System Regulator Operation When generating voltage increases more than the set-voltage of Zener diode ZD, current flows to base B of transistor T2 and collector C is con- nected to emitter E. Current which was routed to base B of transistor T1 disappears due to transistor T2 operation so that transistor T1 is turned OFF. No current flows through filed coil FC and gener- ating voltage at stator coil SC decreases. When generating voltage decreases lower than the set-voltage of Zener diode ZD, transistor T2 is turned OFF and transistor T1 is turned ON again. Current flows through field coil FC and generat- ing voltage at stator coil SC increases.
The above operation is repeated so that the alternator generating voltage is kept constant. Battery Relay RF R 3 R 4 R 5 R 6 ZD Battery SC B R 2 A E FC B C T 2 R 1 C E (F) D 1 T 1 E (E) T157-04-02-009 T2-5-13