Locally or remotely operable electronic lock - has keyboard for entered code and flip=flop and counter controlling opening decision

摘要

The electronic lock can be operated locally or remotely and has an input keyboard acting as a key into which given codes are entered. The keyboard unit's output is connected via code switches to logic. The outputs of the logic are connected to a flip-flop and only set the flip-flop when the data entered is incorrect. If the entered data is correct the logic moves a counter on. The counter determines the correctness of the sequence and is reset after receiving the last pulse from the logic. For the lock to open, two conditions must be met. First, the counter must have been reset, e.g. to zero. Secondly the flip-flop must not have been set. The lock is simple, cheap and effective.