2. Disturbances generated by multimedia devices

2.1 Analysis of power supply operation and disturbances

The multimedia devices studied are :

• a 45 W television set;

• DVD player ;

• a computer ;

• an ADSL modem.

All these devices have built-in power supplies, except for the ADSL modem, which is powered by a switch-mode AC adapter. Today, these converters are increasingly replacing mains adapters that used to be powered by a 50 Hz transformer. The current measured can be used to identify the type of conversion used in device power supplies. Most devices below 75 W use diode rectification combined with capacitive filtering to convert AC mains voltage into DC...