Abstract: A compact and economical probe unit has projecting electrodes for sensing minute voltage variations at spaced apart locations on a persons skin or other surface. Internal circuits generate serial form digital signals indicative of the voltage variations for transmission to a personal computer where an electrocardiogram or other data presentation may be displayed. The probe includes a digital type of optical isolator through which the serial signals are transmitted, the output circuit of the isolator being energized by voltage taken from the computer and the input circuit being independently energized from a battery within the probe and thus there is no electrically conductive path between the computer and the electrodes. Among other uses, the probe enables unskilled persons to monitor their own heart activity as it is economical, safe and easily operated and makes use of a common computer for display rather than a costly electrocardiograph.

Abstract: A door exit device has a pivotal panic bar that is depressable from a raised position to unlatch a door. A lock assembly for the device comprises a pivotal member movable between an engaged position with the panic bar to hold it in its raised position and a disengaged position to permit pivotal depression of the panic bar and opening of the door. The member is mounted on the door and a locking feature is provided to hold the member in at least one of its engaged and disengaged positions. In two described embodiments of this invention, the member comprises an arm pivotally mounted for vertical movements to engage a cross-bar of the panic bar, in a third embodiment an arm pivots horizontally to engage a lever arm of the panic bar, and in a fourth embodiment the pivotal member comprises an extended end of a torsion spring adapted to engage and hold the panic bar in its raised position.