Electric power supply system using back-up capacitor

Claim 1

An electric power supply system comprising: a d-c power source; a first rectifier serially connected to said power source so as to permit a current to flow through said power source in only one direction from the negative to positive terminals of said power source; a pair of output terminals connected across said rectifier and said power source, said output terminals being connected to a load; a first series connection composed of a first protective resistor and a back-up capacitor, connected across said output terminals, said resistor being bypassed by a second rectifier so that a discharge current from said capacitor flows through said second rectifier; a first discharging resistor bypassing said back-up capacitor so as to slowly discharge said back-up capacitor; a second series connection composed of a second protective resistor and a reference charge-storing capacitor, connected across said first rectifier and said power source, said reference charge-storing capacitor being bypassed by a second discharging resistor; a voltage divider composed of first and second voltage dividing resistors, connected acrosss said first rectifier and power source so as to produce a reference voltage; a first comparator for producing a logic ''''1'''' signal when a voltage across said back-up capacitor exceeds said reference voltage; a second comparator for producing a logic ''''1'''' signal when a voltage across said reference charge-storing capacitor; and means for producing information signals representing condition of said back-up capacitor in dependence on said logic ''''1'''' signals from said first and second comparators.