An intercom is a device that allows tenants to communicate with visitors before giving them access to their apartments. It can be used in apartment buildings, homes, and other buildings. These systems can allow visitors to call tenants using their cell phone or landline phone, then use the tenant’s code to unlock the door or gate.
The intercom system is made up of base stations that capture audio and video, then transmit the signals to substations. The base stations can be located in the hallways or other common areas of the building. The base station can also be located inside the apartment itself, so that visitors can press a button or enter a code to call the tenant.
There are several different types of intercoms that are used in different places. Among the most popular are digital intercoms and analog intercoms.
One of the more interesting types is an intercom that uses a special code to identify each apartment. This code is stored in the microcircuit of the subscriber device and is programmed with jumpers for each apartment number.
To change the code on the subscriber device, you will need to carefully examine its microcircuit. There are special digital panels near each jumper on which the numbers in ascending order represent the apartment code.
This code is also stored in the body of the tube, on pins numbered 1-2-4-8 and so on. To replace the apartment code, it is necessary to short-circuit pairs of pins on the board so that the sum of dialed digits equals the apartment number.
An easy way to do this is to connect the plus and minus wires on the bus of tens, and then switch the cable to the bus of units. This will allow you to check whether the new device is working correctly.
A simple intercom schematic is shown above that can be constructed on a proto-board or a stripboard and a Printed Circuit Board (PCB). The circuit will operate on a 9V battery and can be set up to communicate with two other devices.
If you need to add an extra microphone or speaker to the circuit, you can do so by changing the switch positions of S2 into the ‘Talk’ contact and S1 to the ‘Listen’ position. The 8 ohm speaker will then function as both a Microphone and Speaker.
There are many other ways to build an intercom, but this is one of the most practical and easy-to-do projects that can be done by a layman with a little knowledge of electrical engineering. This project is especially useful for school children who need a simple, cost-effective communication device that they can use to talk to other students in their classroom or to teachers in their teacher’s office.
In addition to this, the circuit has a 10K potentiometer that controls the volume and total gain. The circuit also has a double switch that is used to switch between ‘Talk’ and ‘Listen’.