Generator
Nedenfor er lavet et simplificeret diagram over en Moto Guzzi og BMW lade system.

Referering til diagramet:

 

Ledningsfarver (Meget sandsynlig):

DF regulator til Rotor - BLÅ/SORT eller SORT
D+ diode bro to regulator - BLÅ
D- regulator til stel (ground)  - BRUN
 

With the ignition on (switch closed) and the engine off current flows from the battery, through the charge light, the voltage regulator and the rotor to ground. This provides the initial excitation (magnetization) to the rotor to get the alternator working when the engine is started. If the rotor is open (broken wire), the brushes worn out, the charge lamp burnt out or some other fault in this circuit, curent will not flow, the charge light will not illuminate and the alternator will not operate correctly.
With the engine on and running fast enough for the alternator to produce a voltage above that of the battery (ie it is charging), the voltage at the B+ and D+ terminals of the diode board are equal. Because of this no current will flow between the D+ and B+ terminals and the charge light will be extinguished.

Current from the B+ terminal will go to charging the battery and current from the D+ terminal will be available (via the voltage regulator) to magnetize the rotor.

As the rpm drops, the alternator will not produce sufficient voltage to charge the battery and the voltage at the D+ terminal will drop below the voltage of the battery. Because the B+ terminal is tied directly to the battery, its voltage will be maintained at battery voltage.

The voltage at the battery is now higher than the D+ voltage and current will therefore flow from the battery through the charge lamp, the voltage regulator and the rotor to ground and the charge lamp will again light.
As the RPM increases the voltage at D+ again increases until it equals battery voltage and the lamp again goes out. When the voltage at the D+ terminal (which is equal to the B+ terminal if the voltage is above the battery voltage) exceeds a specified voltage, the voltage regulator cuts power to the rotor, reducing its magnetism thereby limiting the maximum voltage output from the alternator to a safe value.
From this you can understand the common test for the voltage regulator. Remove the regulator, and short the DF and D+ terminals in the plug. With a voltmeter across the battery, does the voltage increase to 14.5 volts and more as the RPM's are increased? (Stop at 15 volts as damage can result). This test works because the voltage regulator is out of the circuit - remember that the voltage regulator is really a voltage limiter.

Selve regulatorens opbygning:

D+ og D- er forbundet til den positive og negative batteri poler, hver sin, og bruges til at ”måle” spændingen på batteriet.
DF er forbundet til felt vindingen L, som er vekselstrømsgeneratoren rotor vinding. I lade systemet som er brugt i en Moto Guzzi eller BMW, er den anden ende at rotoren forbundet til konnektere til stel D-


Se mere på http://homepage.sunrise.ch/mysunrise/joerg.hau/mot/voltreg.htm
Voltage regulator home-made.