1. Alternator Functional Diagram

2. Alternator Functional Diagram
DC Current Applied to the Rotor

3. Alternator Functional Diagram
3-Φ AC Output from the Stator
DC Current Applied to the Rotor

4. Alternator Functional Diagram
3-Φ AC Output from the Stator
DC Current Applied to the Rotor
Six Output Diodes Two per Phase Full-Wave Rectifier

5. Alternator Functional Diagram
3-Φ AC Output from the Stator
DC Current Applied to the Rotor
Six Output Diodes Two per Phase Full-Wave Rectifier
Three Diodes One per Phase Sample Battery Voltage

6. Alternator Functional Diagram
2 Inputs
Regulator Controls the Amount of Field Current applied to the Rotor

7. Regulator Inputs Control Voltage Input Field Current Supply
Controls current through the Rotor
Field Current Supply
One input from the alternator via the Diode Trio
Second input from the battery via the warning lamp

8. Regulator Action
If the battery voltage drops, more current applied to the rotor, increasing the magnetic field strength, increasing the alternator voltage output.
If the battery voltage increases, less field current applied to the rotor, reducing the alternator voltage output.

9. Field Current Supply Two Sources Turn ignition ON,
Alternator via the diode trio
Battery via the warning lamp
Turn ignition ON,
Source of field current is the battery via the ignition switch and the warning lamp

10. Field Current Supply (continued)
After engine starts,
Alternator is up to speed, output of diode trio is fed back to the regulator and serves as the source of the field current.
Alternator is now self-sustaining

11. Alternator Circuitry

12. Warning Lamp Turn ignition ON, Alternator at full output,
Current flows through warning lamp, transistors, and field coil to ground, causing the lamp to illuminate.
Alternator at full output,
Voltage from diode trio equals the battery voltage
equal voltage on both sides of lamp
lamp goes out.

13. Warning Lamp (continued)
If the alternator fails,
Voltage out of diode trio drops
Lamp illuminates from the battery voltage
If the battery fails,
Battery voltage drops
Lamp illuminates from the alternator voltage

14. Sample Battery Voltage
Inside the Regulator
IC1+Ic2
Ic2
Field Current
Ic1
Sample Battery Voltage

15. Regulator Circuit When battery voltage is OK, D1 conducts T2 conducts
Less current through T1 collector
T3 turns Off
Field current now reduced

16. Regulator Circuit (continued)
When battery voltage is low,
D1 is Off
T2 is Off
More current flows through T1collector
Transistor T3 turns On
Field current increases