The Campden Instruments 81425EA chamber interface module interfaces to the Lafayette Instrument ABET II operant controller or the Campden 81426 operant controller to the operant equipment. The unit includes white noise and tone generation as standard and gives screw terminal access to the control I/O lines and power supply. The unit provides eight isolated outputs for connection to equipment requiring low voltage, electrically isolated control/ timing signals. The unit also provides two electrically isolated TTL compatible input lines.