A Portable Oscillograph With Unique Features

This paper describes a simplified portable oscillograph having a number of new optical and electrical features. The optical system, which consists of a combination of cylindrical lenses with axes at right angles, is designed to permit simultaneous viewing and photographing. A continuous time axis for both the viewing screen and film is secured by means of a small, variable speed, revolving mirror. New galvanometers have been developed which have electromagnetic damping instead of the usual oil damping. These galvanometers are very rugged and have been built for recording frequencies as high as 14,000 cycles per sec. The oscillograph is entirely self-contained and may be operated from a 110-volt 80-cycle lighting circuit without auxiliary attachments. The compactness and portability of the instrument can be seen from its over-all dimensions which are 8 × 11½ × 11 in. and from its total weight, which is approximately 18 lb.