| 摘要 |
An electronic lock mechanism in which the odds against picking or unauthorized opening are extremely high, and wherein an electrically operable bolt is connected with the output of an oscillator in the bolt control circuitry that includes a resistance bridge network including regenerative differential electronic switches connected to selectively activate a pair of relays with series connected contacts in accordance with the direction of unbalance of the bridge, and to activate both relays in response to a balanced operative mode of the bridge so that the relay contacts will coact to close a power supply connection to the oscillator. A control key insertable in a mating keyhole is operative to connect the bridge with a voltage source, insert a resistor component into the bridge network of a value to balance the bridge, and also place a resonating capacitor into a tuned circuit of the oscillator and thereby activate the lock bolt to an unlocked position. An additional security feature includes an RC circuit for introducing a predetermined delay in the time required for the bridge to reach a balanced operation mode.
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