Coded Access Device
An electrical lock mechanism includes a series of sequentially connected memory storage elements, such as flip-flops, terminating in one or more electrical and/or electromechanical devices that control an external function. Entries into the circuit are made from a plurality of remote switches or switching devices connected to interlocks or logic elements, such as nand gates, that are connected between adjacent memory storage elements. Entry to the circuit through the interlocks in a single predetermined sequence allows for the setting of successive memory elements; the memory elements serve to nullify any progress through the sequence if an incorrect entry is made. An exchangeable code module between the switches and the circuit allows for the changing of switch combinations. The predetermined code may require the correct selection of single switches in a particular sequence, as well as simultaneous entries from a plurality of switches. Several circuits may be connected in series, such that a plurality of individuals having knowledge of their respective portion of the sequence are required to effect the proper combinations. A simple circuit allows for about 50,000 possible combinations, and several million possible combinations may be easily attained.