An intercom enables you to speak to whoever comes to your door while within the safety of your home or office. It is also used for intra-office communications.
Electric Strikes are security locking devices that are found in places where access control is required. They are also known as Door Strikes or Door Releases. They are controlled by Low-Voltage electrical power sources.
Electric strikes come in many varieties. They can be 12 or 24 or even higher voltage and they may take AC or DC current and some even take both. They may be fail safe or fail secure.
A fail safe electric strike needs power to keep it locked. A fail secure electric strike stays locked even without power.
The most common by far is a fail secure. When using a fail secure electric strike even without power it stays locked from the outside coming in.
When you need that buzzing sound you may have heard when being buzzed into an office that`s the sound of AC current going through the electric strike. If you need this sound as a signal to push on the door when unlocking the strike then choose an AC electric strike and an AC power source or transformer.
If you do not want or need this buzzing sound then choose a DC power source or transformer.
The DC strike is almost completely silent when it releases except for a slight click sound. On average a DC electric strike will last longer than an AC electric strike. Nowadays there are strikes suitable for nearly all door styles and materials.