This regulator employs solid state circuitry throughout. The transistors,
diodes and resistors are mounted on a printed circuit board contained
within a sealed aluminium case which is suitably finned for the maximum
heat dissipation. No cut-out relay is required because the rectifier
bridge in the alternator prevents current flowing from the battery
through the stator when the alternator is stationary or generating less
than the battery voltage.
Current control of the alternator is achieved by using the voltage drop
across a precisely engineered shunt (integral in the regulator board)
carrying output current. An amplifier senses this voltage drop and
accordingly produces a switching signal. This signal is used to operate
the driver stage of the regulator to control the alternator output by
field switching. Voltage control is obtained by measuring the system
voltage with a zener diode as a reference and again using alternator
field switching to regulate this output. As battery charging progresses,
control of output changes from current control to voltage control.
