Simple password lock circuit that can alarm

Circuit working principle: S. in Figure 5-2a. For the alarm switch . If S is pressed,
relay K. It works with electricity, two sets of normally open contacts K. ,K,. Pull it on to make the alarm bell
sound. At this time, even if you release s. The alarm sound is still loud, and the alarm can only be stopped by cutting off the power supply after the owner arrives
. so,S. , S6 is the effective switch. After pressing so, the K2
relay is energized, and the two sets of normally open contacts K2A and Kze are closed; finally, by pressing S6, the K4 relay
can be energized, K. A. The K4B normally open contact is closed, thereby turning on the power of the electronic lock
and opening the lock smoothly. Note that the opening order of so, s8, and S6 cannot be reversed, otherwise it will be invalid.
S: One S, S7, and S9 are normally closed push button switches. Do not press several switches when unlocking , otherwise
the circuit will be disconnected and the K2, K3, and K4 relays will lose power again. The unlocking password set in this circuit diagram
is "086". Of course, readers can also reset the unlocking password.