Simple code lock / Norfazilah Li and Wan Nurul Hilwana Wan Mohd

The simple code lock is a simple security system. The circuit described is of an electronic combination lock for daily use. It response only to the right sequence of four digits that are keyed in correctly. If a wrong keys is touched it resets the lock. The circuit is built around two CD4013 dual-D flip-flops ics. The clock pins of the four flip-flop are connected to a,b,c and d pads. This pad will generate the ics when the combinational digits are right. The correct code sequence for energisation of relay is realized by clocking points a,b,c and d in that order. The four remaining switch a/b/c/d briefly pull the clock inputs in high and the state of flip-flop is altered.
This circuit can be usefully employed in cars so that the car can start only when the correct code sequence is keyed in via the key pad. The circuit also can be the safety code. Which it will be our secret number to make sure our safety. It can employed in safety box, door and various other applications.