Bridge rectifier: to convert AC to DC, but at this stage the DC output is unstable yet

Electriolytic capacitor: to smooth the unstable DC output to a stable ripple

Voltage rectifier: to eliminate ripple by setting DC output to a fixed voltage

For door access control panel connection,

1. Connected the electric lock with port 1, 3(fail secure) or port 2, 3(fail safe),

2. Connect the access control panel with port 4 & 5(for power supply)

3. Connect the push button with port 5 & 6(equal to exit button)

4. Ports 7 & 8 are preserved for power supply to access control panel

5. Ports 11 & 12 are for battery charge/discharge.