A cathode-ray oscillograph with rotating-drum camera

THE equipment and methods to be described have been developed to meet a need for a simple and effective means of photographing recurring or non-recurring waves viewed on the screen of the cathode ray oscillograph. The recording camera is simple and easy to operate and very economical of film. The recording method also provides for photographing any number of voltage or current waves, and later comparing the phase angles of all the waves. This oscillograph is designed primarily for slow speed work, particularly on waves of 60 cycle fundamental frequency, and in this feature is entirely different from the high speed cathode ray oscillograph described by Kuehni and Ramo.¹ The cathode ray tube used is a high vacuum, seven inch screen tube. The screen is of the “fast” type with a highly actinic spot of short persistence. A suitable enclosing sheet steel case and a separately boxed 3,000 volt d-c power supply unit were constructed. When the equipment is used for visual work, sweep voltage is applied to one pair of deflecting plates from an independent sweep circuit.