Variable Bandpass Ripple Amplifier

When all of the rotating diodes are operating normally, the field current

ripple is of small amplitude and high frequency. When a diode is faulty,

the ripple is of large amplitude and low frequency (one-third or one-sixth

of normal). Thus, the ripple amplifier has a high gain at low frequencies

and a low gain at high frequencies.

The amplifier provides adjustment of the high frequency gain to provide

compatibility with a wide variety of brushless generators.

Precision Rectifier

This rectifier converts the ac output of the ripple amplifier to a dc signal.

Inverse Timer

The dc output of the precision rectifier passes through an inverse timing

network to provide prompt tripping for a shorted diode but allow longer

delays for an open diode.