Electronic lock circuit diagram

electronic lock

This is the electronic combination lock I use for my outdoor door. The functionality is software-based. When someone enters a valid code, it activates a relay (typically used for opening the door) for a few seconds. This relay can operate either an energized unlocking lock with a short-circuit contact or an energized holding electromagnetic lock with a short-circuit contact (we need the relay because these locks typically use AC, not DC). The code can be changed at any time after the current code is entered.