The AC adaptor (AD2410) provides up to 1.0A of current at a nominal 24VDC UL CE and CSA approved Universal input, operating at any voltage from 100 to 240VAC at either 50 or 60 HZ The PS4 system interface provides precise voltage regulation, further smoothing of the DC current (AC hum elimination), automatic overload/short-circuit protection, the necessary termination network for the intercom circuit, an LED which indicates that 24VDC is being delivered, and 3 paralleled XLR jacks for connection of headset stations or strings of stations in a party-line configuration.