The circuit is quite old using CMOS 4081 with 4 ‘AND’ gates to hardwire the access code. [myvideoisonutube] references [Ron’s] “ Enhanced 5-Digit Alarm Keypad ” schematic for this build ...

The Ramos clocks designed by Paul Sammut require a snoozer to get out of bed and enter a code on a number pad located in another room to silence the alarm buzzer.