Description:

HQS1436 is a simple electronic password lock circuit; AN0~AN9 is for password input; LOCK is locking key; UNLOCK is unlocking key; Can input max. 6-digit password; In locking state, D1 is off; In unlocking state, D1 is on when password is more than 6 digits, D1 is off when less than 6 digits; In locking state, D2 is on, JDQ1 pull-in; In unlocking state, D3 is on, JDQ1 releases; C1 is filter capacitor; R1, Q1 are for driving the buzzer; R2, Q2 are for driving the relay; D4 to prevent Q2 from getting destroyed by the reverse voltage of relay; R3 is current-limiting resistance; Press the button, the buzzer will sound.

How to use:

Unlocking state: Power the module, it will automatically be in the unlocking state, the replay is opened, D3/D1 are on, once the password is more than 6 digits, D1 will turn off; Can delete the password by pressing UNLOCK; Press LOCK to memorize the password and enter the locking state, D2 is on and the replay is closed, D3/D1 turn off.

Locking state: D2 turns on, the replay is opened; Can delete the password by pressing LOCK; Press UNLOCK to compare the unlocking password with the memorized password; If they are the same, then enters unlocking state, D2 turns off, the relay is opened, D1/D3 turn on; If they are not the same, buzzer will sound and D1 will flash 3 times once inputing wrong passwords for twice; The third time inputting wrong password, the buzzer will keep sounding and D1 will keep flashing; Then the system will be locked until power off.