Abstract: A standby power supply dedicated to a peripheral electronics apparatus on aircraft provides an isolated ungrounded self-contained source of DC operating voltage. That source is applied to the electronics apparatus upon indication of turbine generator shut-down or failure before the voltage generated by the turbine generator completely falls off. Formed with an EMI filter, a fast pulse mode battery charger, a lead-acid battery pack, a DC to DC converter, and a pair of electromagnetic relays, the standby power supply ensures that the electronic apparatus is never without operating power even momentarily.