Voltage sensing, autoselecting aircraft power supply interface

An autoselecting power supply for producing a regulated DC voltage output from an input AC or DC aircraft power source, the power supply comprising:

• a pair of input terminals for connection to the aircraft power sources;
• an AC-DC power converter for producing a first regulated DC voltage output from an AC aircraft power source connected to said pair of input terminals;
• a DC-DC power converter for producing a second regulated DC voltage output from a DC aircraft power source connected to said pair of input terminals;
• first and second voltage sensors connected to said input terminals, said first voltage sensor producing a first trigger output when an AC voltage is present at said input terminals and said second voltage sensor producing a second trigger output when a DC voltage is present at said input terminals;
• a first switch responsive to said first trigger output for electrically connecting said pair of input terminals to said AC-DC power converter;
• a second switch responsive to said second trigger output for electrically connecting said pair of input terminals to said DC-DC power converter;
• and
• an override circuit for disabling said second voltage sensor from producing said second output when an AC voltage is present at said input terminals.