Electronic video doorbell circuit

When switch S is turned off, it is an ordinary doorbell. When gBl or SB2 is connected, it will ring "ding dong* three times. When s is turned on, it is a video doorbell. When someone comes, connect SB1 and the incoming person will be displayed on
the TV . The door light will light up and the delay will After Imin, the TV will automatically turn off and the door light will automatically go out. If you place the door light indoors and replace it with a string of colored lights, the visual doorbell for
deaf-mute people will be disabled . Press SB2 or SB3 to watch the situation outside the door. If you press SB2, the doorbell will make a sound. .Press SB3 to monitor outdoor conditions silently