Combination Lock

 

The CD4016 contains four electronic switches that can be operated with control current. The relay in this circuit will operate only if A and B switches are on (switched to the +9V side) and if C and D are off. You can experiment with different connections to make your own combination, or substitute rotary switches with additional contacts.

 

 

 

 

Copyright by Bill Bytheway, K7TTY February 2012