The so-called radio center allows local announcements, news and hazard warnings to be broadcast within the building. Loudspeakers located in each of the rooms are connected to the node with wires. how to make local radio?
Instructions
Step 1
Calculate the power of the radio site amplifier. According to the standard, the power supplied to one subscriber loudspeaker is 0.15 W. But in series with each of them, a protective resistor is turned on, on which the same power is allocated. Therefore, when calculating the radio network, take the power equal to 0.3 W per point.
Step 2
Select all loudspeakers rated for the same voltage (15 or 30 V). Some of them are equipped with transformers with taps allowing you to select any of these voltages - then switch them all to the same voltage. Imported loudspeakers can be rated for 70V, but some have taps for switching to 30V.
Step 3
In each loudspeaker, turn off the volume control, if there is one, to ensure that the alert is heard. For the same purpose, do not use sockets and plugs to connect the speakers. Connect the leads of the primary winding to the line, bypassing this regulator, but through a two-watt resistor, the value of which is equal to the resistance of the primary winding of the transformer at direct current. Place this resistor in a protective casing outside the speaker cabinet.
Step 4
Connect all series-connected loudspeakers and resistors in parallel. Bring the line to the location of the amplifier. Select the wire cross-section with a margin depending on the total current in the line. Calculate it by dividing the power by the voltage.
Step 5
Measure the voltage swing at the amplifier output. Connect a step-up transformer to its output, the transformation ratio of which is selected in such a way that at the output at maximum volume, a voltage is obtained that is slightly less than that for which the loudspeakers are designed. The DC input impedance of the transformer should not be less than that for which the amplifier is designed, and the transformer power should not be less than the calculated one.
Step 6
Turn on the amplifier and connect a microphone to it. If your amplifier does not have a microphone input, use a dedicated microphone amplifier. Speak continuously into the microphone, and have the assistant go around all the loudspeakers and make sure that none of them is silent. Even those loudspeakers that are located as far away from the amplifier as possible should sound loud.
