| 摘要 |
A DTMF-code controlled lock device mainly composed of tow units: a key control unit and a lock-body control unit. The key control unit, adapted to be carried by a user includes a dual-tone multifrequency (DTMF) encoding circuit with a keyboard and an amplifying circuit respectively connected thereto for inputting and outputting an unlocking DTMF code. The lock-body control unit, adapted to be installed in a door together with a door lock, includes a transducer for transferring the DTMF code signals received from the key control unit, a pair of amplifying circuits connected in series with the transducer, a decoder with its input connected to the amplifying circuits for decoding the DTMF signals into a BCD code, a CPU with a pair of memory units coupled with the output of the decoder for comparing the BCD code with pre-stored one therein, and a relay circuit coupled with the CPU in connection with the lock bolt for effecting unlocking operations upon being energized by the CPU if the comparison finds the two identical.
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