See the little ball near the reset Pad connection? Connect the output of the 555 Delay to it thru a 1k resistor. Then set the delay pulse time. If the correct 4 numbers aren't input in the allotted time, the pad resets and you have to start over If you are looking for a delay on each of the keys being pressed, it gets a bit tougher. You'll have to use AND or NAND gates for each, with one common leg of each tied high/low, the other leg of each tied to the DELAY and the Keypad and the outputs of the AND/NAND going to the 4013s. EZ PZ