Abstract: A battery charging system includes an alternator with a rectifier connecting the alternator output to the battery. A voltage rectifier controls the current in the alternator field winding in accordance with the battery voltage. A transistor switch in the voltage regulator controls the bias current to the output stage of the regulator and is in turn controlled by a differential amplifier through a diode pump. The differential amplifier is connected to detect the presence of an a.c. on one phase of the alternator and causes the transistor to be switched off, disabling the output stage of the regulator, whenever no a.c. signal is present.

Abstract: A brake pad wear detection system comprises a brake having a brake pad and a conductive braking face, the brake pad and the conductive braking face engaging during braking. A sensor loop is embedded in the brake pad and positioned to be broken when the wear to the brake pad exceeds the working limit. An indicator means and a detecting means for operating the indicator means are provided, the detecting means detecting contact between the sensor loop and the braking face as well as breakage of the sensor loop.

Abstract: A battery charging system includes a pair of alternators having rectified outputs which are connected in parallel. The field currents of the respective alternators are controlled by respective oscillatory switching circuits which are responsive to rectified output voltages from the respective alternators. Each respective switching circuit is coupled to an output voltage sensing circuit of the other alternator, so that oscillatory switching of one switching circuit causes oscillatory switching of the other switching circuit.