Using the principles of sound transmission and amplification, we can create a system to keep us in communication over small distances, i.e. we can create a small private line of communication in different areas of our house and even with neighbouring houses. Today, we will look at how to make a home telephone system.
- A radio/recorder with microphone input and headphone output.
- 4 x 8W speakers.
- Duplex cable No. 22 or similar.
- 2 banana plugs that fit into the inputs of the radio recorder.
- 2 wooden, metal or plastic boxes about 30 cm high, 10 cm wide and 5 cm deep.
Assembling the home phone system
First, we are going to create some sound amplifiers. To do this, we drill a couple of holes in each box to fit the speakers. To fix them, we use silicone or another adhesive material of our choice.
Once the sound amplifiersIf you want to connect a duplex cable connection to each speaker of each of the sound amplifiers, it is time to make a duplex cable connection to each speaker of each of the sound amplifiers. The dimensions of each cable connection should be about 5 cm or more, depending on the dimensions of the sound amplifier enclosures.
When making the connection, the polarity of the wires must be taken into account: the red or white line goes to the positive pole, while the other line (usually blue or black) goes to the negative pole. The free ends of the wires are pulled out through a small hole in the back of the boxes.
Now, we make the first connection. The speakers on the underside of each of the sound amplifiers will be connected to the banana type device respecting the polarity (remember that the positive pole is the central terminal of the connector). This connector will be the one that will be connected to the microphone input of the radio/recorder (telephone exchange).
Repeat the same procedure with the upper drivers of the sound amplifiers and connect them to the headphone input of the radio/recorder.
Then we adjust the volume of the radio/recorder (telephone exchange) and we can speak through the lower speaker of the sound amplifiers and listen through the upper speaker, just like a home telephone.
If we want to increase the number of telephones, we must add as many sound amplifiers as we want, in this way, we can have a home phone system for private communications.