| 摘要 |
A lock box in a secure entry system for use with a source of DC power having high frequency pulse width with modulation thereon comprising a housing and a key container mounted in said housing movable between accessible and inaccessible positions. Circuitry is provided within the housing for controlling the movement of the key container and is adapted to be connected to the source of DC power. The circuitry includes a filter having a capacitor. The circuitry is capable of receiving the high frequency pulse width modulated DC power. The capacitor serves to supply at least some of the power required by the circuitry during the time the pulse width modulation is occurring on the DC power supplied. A latch mechanism is provided to prevent opening of the key container to an accessible position by hammer blows applied to the housing.
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