The combination of a gaseous tube rectifier and a d-c motor recently has become quite popular, often with disastrous consequences for the gaseous tube. Behavior of a d-c motor is in many respects equivalent to that of a very large capacitor. An engineer aware of the severe conditions imposed on a gaseous rectifier feeding into a capacitor input filter, may connect a d-c motor to a gaseous rectifier, not realizing he may be imposing worse conditions than is the case with a capacitor.