Guide: RFID for your front door

Most access control solutions use an electronic door strike, which gives way when activated so you don't have to unlock or turn the doorknob; you just push (or pull) the door open. This is exactly what's used to "buzz" someone in a door. That buzzing sound is AC power rushing through the magnetic coil windings in the door strike, pulling up and vibrating the pin that normally keeps the strike in the closed and locked position. You're going to use DC power to operate your electronic strike, so all you should hear is a slight click..