3 V mains supply for portable radios

Most small portable radios require a 3 V supply normally provided by two size AA or AAA batteries. Since rechargeable batteries are an option with many of these radies, most of them are fitted with a charger socket. When such radios are used in a stationary condition, e.g. in the kitchen or in the office, it is useful (and economical) to use the mains operated supply described here.