Electronic Relay Tester 



By T. E. DAVIS and A. L. BLAHA 



(Manuscript received September 24, 1953) 



An electronic relay tester has been developed to gauge the contacts of a relay 

 while it is pvlsing. The device provides a visual presentation of the gauging 

 position of up to 16 contacts at one time. The equipment has been developed 

 primarily as a means for rapid inspection and concurrent adjustment 

 (when needed) in relay mariufacture. It may also be used as a laboratory 

 instrument for studies of timing, chatter, and other performance charac- 

 teristics of relays. 



INTRODUCTION 



Electronic equipment has been developed to gauge up to 16 relay- 

 contacts simultaneously as the relay operates or releases in pulsing. The 

 system provides a visual presentation on an oscilloscope of the gauge 

 points where the relay armature opens or closes the contact. The position 

 of the armature is sho^\^l by the horizontal position of the scope beam. 

 Each particular contact is represented on the scope by one of 16 hori- 

 zontal lines generated by the motion of the armature. A vertical step 

 on a line indicates the gauge point at which the contact operates. 



The device consists of three main parts: (1) An electrostatic gauge to 

 indicate the position of the relay armature, (2) An electronic scanner 

 that continually switches across all the contact pairs, and (3) A bright- 

 ness control circuit to intensify the beam of the scope when the armature 

 is mo\dng. Fig. 1 shows a schematic diagram of this equipment. 



As shown on Fig. 2 the scope, test relay jack and electrostatic gauge 

 are mounted on a bench. The scanner, power supplies and control cir- 

 cuits are mounted underneath the bench. 



ELECTROSTATIC GAUGE 



As the relay armature moves, its position is indicated at all times by 

 the horizontal position of the scope l)eam in response to the output volt- 

 age of the electrostatic gauge, which is applied to the horizontal plates. 



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