The following circuit diagram is applicable for XCOM Intercom Device. Here you will find detail pinouts diagram of the device, i.e. Pin 1 Pilot Microphone, Pin 2 Co Pilot Microphone, Pin 3 Music Audio Input, Pin 4 COM 1 Audio Input, Pin 5 AUX Audio Input, etc. Pin No. 9 is the positive in, connect to a battery or to your positive wires in the aircraft, it MUST have a 500 ma fuse fitted. Pin No. 11 must be connected to a good ground, a lot of radio / intercom problems come back to a poor ground, ground to radio chassis also.