This circuit diagram it is a very simple electronic key lock that can be used for alarm systems or other devices that can be activated by an electronic relay .
This electronic key lock circuit use few logic circuits and some other common electronic components .
The code is formed by a 5 numbers keys . Switches S1 through S5 must be operated in rapid sequence to operate the look . S1 ,S2,S3,S4,S5 can be any numbers on 10 buttons switch pad .

The electronic key has also 5 false buttons , which activate the alarm ( relay ) if one of them is pushed . If an incorrect button is pushed and alarms sounds , the circuit is disabled for two minutes .
This electronic circuit project require a 12volts power supply and the electronic relay used must be a 12 volts relay . All the keypads can be placed on a printed circuit in order you want, to make the code .
All diodes used in this projects are 1N4148 type .