KELAY AlEASUKING EQUIPMENT 



13 



Photo of lA recorder setup. 



transducer elements whose motion is controllable to simulate a wide 

 range of slide conditions typical of possible designs, from which Avear 

 measurements may be taken and analyzed. Such methods were also 

 described in the previous reference.' The measurements may be made 

 either by means of a barium titanate element or by means of a phono- 

 graph recording head such as the Western Electric lA recorder. Because 

 of the feedback coil and amplifier circuit, the latter transducer will 

 generate the precise amplitude of motion desired for any particular test 

 merely by properly setting its input current. It is normally driven at 

 frequencies in the order of 1 ,000 cycles, permitting a large number of 

 slides to be obtained in a short time and affording information to the 

 designer on a very accelerated basis. Through the choice of different 

 amplitudes, different materials to be tested, and different forces between 

 them, a wide range of variables can be covered, to guide the designer in 

 the proper choice of materials and conditions of use. A recorder setup 

 for a typical test is .shown in Fig. 7; data taken on a typical set of parts 

 for an AI'' type relay are shown in Figure 8. 



