Abstract: An ink priming system for a multi-pen recorder of the gravity-fed capillary tube type comprises a gas manifold common to all of the ink bottles individually provided for each channel of the recorder. Individual control valves may be selectively actuated by the operator to prime each pen. When the control valve is closed, the gas pressure is bled off so that the inking system thereafter acts as a normal gravity-fed capillary tube system. A non-clogging inking system is provided by utilizing a short length of flexible thin walled tubing to supply ink to the movable recording pen. The length of this tubing is sufficiently short that evaporation of the ink solvent through the walls of the tube is accompanied by diffusion of the dye back to the ink bottle so that the concentration of dye in the ink at the end of the tube adjacent the recording pen does not exceed saturation value during prolonged periods of non-use of the recorder.

Abstract: A multi-channel instrumentation system is provided wherein signals from selected electrode pairs are sequentially connected to the isolated input of a common signal amplifying path. The electrode pair selecting means is included in a portable head box which may be placed adjacent to the patient to be tested. Included in the head box are facilities for testing the impedance of any selected one of the patient electrodes and providing a visual indication of the magnitude of such impedance. The head box also includes facilities for selecting a group of patient electrodes which are connected together and used as an average or reference potential for one input of the common signal path. Facilities are also provided for calibrating the common signal path by applying a d.c. calibration signal to the input thereof by means isolated from sytem ground.

Abstract: An improved multi-channel galvanometer assembly is disclosed particularly well adapted for use in such instruments as electroencephalographs and the like. The assembly includes a soft steel combination return path structure and frame supporting a plurality of galvanometer movements. The design employs pairs of samarium cobalt magnets held in place adjacent and on opposite sides of the coil of each galvanometer by magnetic attraction to the steel return path structure. The galvanometers themselves are each mounted on an aluminum support plate which also serves as a shield to prevent magnetic coupling between adjacent galvanometer coils when the galvanometers are assembled in the support frame. The galvanometers on their support plates are each individually removable and/or replaceable. The result is a lighter, smaller, multi-channel galvanometer assembly which is readily expandable and easily serviced.