There's a photoelectric alarm system outside the compartment, and Jim Saddler is sitting just inside the door.
Certainly no doors had swung open or closed behind him, and photoelectric alarm system without visible manifestations could be dismissed as a not too likely possibility.
There are twenty-five square miles of fortified defenses--photoelectric eye installations.
If he were being watched mechanically, there was nothing he could do about it and somehow he didn't think that he had crossed any photoelectric beams.
The photoelectric cells of their eyes looked pale and repulsive; the square audion-screens of their ears however made up for that by the comical precision with which they turned in every direction at the sound of a commanding human voice.
Read-In - When this switch is operated, the photoelectric paper tape reader will start operating in the Read-In mode.
The whole matter is of more practical importance than appears at first sight, for the photoelectric nature of the effects involved in the radiative treatment of many cruel diseases seems to be beyond doubt.
The flash of light produced when an individual ionizing particle or ray strikes a sodium-iodide crystal is noted by a photoelectric cell.
Luis Gofredo saw to it that the camp itself would be visible-lighted, and beyond the lights he set up more photoelectricrobot sentries and put a couple of snoopers to circling on contragravity, with infra-red lights and receptors.
