Patent ID: 8018696

Claim:
A tertiary lock system power unit for supplying a DC tertiary lock control signal to an electromechanical tertiary lock assembly, comprising: a step-down transformer adapted to receive a tertiary lock release command signal, the tertiary lock release command signal being an AC signal of a first peak voltage magnitude, the step-down transformer operable, upon receipt of the tertiary lock release command signal, to supply an AC signal of a second peak voltage magnitude, the second peak voltage magnitude being less than the first peak voltage magnitude; a rectifier circuit coupled to receive the AC signal of the second peak voltage magnitude from the step-down transformer and configured, upon receipt thereof, to supply a DC signal of a third voltage magnitude; and a voltage limiting circuit coupled to receive the DC signal of the third voltage magnitude from the rectifier circuit and operable, upon receipt thereof, to supply the DC tertiary lock control signal to the electromechanical tertiary lock assembly at a fourth voltage magnitude, the fourth voltage magnitude less than or equal to a predetermined voltage limit, the voltage limiting circuit comprising: a voltage limiter coupled in parallel with the rectifier circuit and configured to limit the DC tertiary lock control signal to the fourth voltage magnitude, the voltage limiter including a first terminal, a second terminal, and a third terminal, the first terminal coupled to the rectifier circuit, the second terminal coupled to the rectifier circuit and adapted to couple to the electromechanical tertiary lock assembly; and a voltage follower circuit including at least an input terminal, an output terminal, and a control terminal, the voltage follower circuit input terminal coupled to the voltage limiter first terminal, the voltage follower circuit control terminal coupled to the voltage limiter third terminal, and the voltage follower circuit output terminal adapted to couple to the electromechanical tertiary lock assembly; a resistor circuit and a zener diode circuit electrically coupled in series with one another, the resistor circuit electrically coupled in series between the first and third terminals, and the zener diode circuit electrically coupled in series between the second and third terminals; and a diode circuit electrically coupled in series with the resistor circuit and the zener diode circuit.