390 



ELECTRICAL MACHINERY 



set or a synchronous converter, and some simple, cheap 

 device must be used. 



A vibrating rectifier has been designed and is on the 

 market which furnishes a few amperes of uni-directional 

 current at 10 volts or less. It consists of a polarized 

 armature which is so pivoted that when acted on by 



Ground* (} Q *) (\ A ) 



-U 



FIG. 256. Connections of the Vibrating Rectifier. 



an a-c. magnet it vibrates back and forth. A diagram 

 of the connections is given in Fig. 256 and a cut of the 

 device is given in Fig. 257. When E is positive (with 

 respect to H) the battery is charged through the contact 

 C and when F is positive (with respect to H) the battery 

 is charged through the contact C'. These contacts must be 

 adjustable so that sparking may be eliminated. This 



