An Apparatus for Studying the Motion of Relays

Herbert E. Ives, T. L. Dowey
1922 Journal of the Optical Society of America  
In the study of the electrical phenomena accompanying the making and breaking of contacts by relays, it is of considerable importance to know definitely how the contact points move relatively to each other. The electrical methods which have been commonly employed for determining relay characteristics are quite inadequate for the kind of study here in mind. Oscillographic records of current tell merely whether contact is single of multiple, without any direct indication of the nature of the
more » ... nature of the motions which result in contact. Methods for measuring the velocity of relay arms depending on time determination by the charging of condensers are only applicable to clean makes or breaks and so are impracticable for the study of the very important case of "chattering." The apparatus which is illustrated in Figures 1 and 2 was designed for the purpose of obtaining photographic silhouettes, or "shadowgrams" of the moving contact points. The optical arrangement, while presenting no essentially new features, is one which is made eminently practical by the availability of an extended light source of high brightness, in the "pointolite" lamp. By reference to Fig. 1 the manner of its use will be made clear. First of all an enlarged image of the incandescent pointolite ball is thrown by means of a lens into the plane of the relay contacts. Then an image of the contacts and the pointolite image is formed by a second lens upon a narrow slit, parallel to the direction of motion of the contacts, and lying closely in front of a rapidly moving photographic film. It is clear that the shadow traced on the film will be a record of the relay's motion. The remaining problem is one of mechanical and electrical design to secure the proper control of film speed, the 391
doi:10.1364/josa.6.000391 fatcat:rkbej3nqvncqbjuqtwkxdma7fq