Abstract: The method of balancing a rotor having multiple blades and defining an axis of rotation, and wherein structure proximate the rotor is subject to vibratory motion due to dynamic unbalance of the rotating rotor and an out-of-track condition of the rotor blades, the method employing two vibration pickups, the method including:A. operating the pickups to produce vibratory signals corresponding to up and down vibratory motion of the structure at port and starboard sides of said axis,B. combining said signals to produce a resultant oscillatory output signal characteristic of rotor vibratory motion due substantially to only one of said conditions,C. using said resultant output signal to alleviate said one condition.

Abstract: A starting device for a gas discharge lamp, to whose electrodes AC voltage is applied, comprises:A. first means electrically connected with at least one lamp electrode to apply to the lamp a transient voltage pulse which initially changes in amplitude in a polarity direction relatively in opposition to the polarity of the main voltage simultaneously supplied to the electrodes,B. said first means including circuitry to cause said pulse to thereafter change in amplitude in a polarity direction in aid of the polarity of the main voltage simultaneously supplied to the electrodes.

Abstract: A starting device for a gas discharge lamp, to whose electrodes AC voltage is applied, comprises:a. first means electrically connected with at least one lamp electrode to apply to the lamp a transient voltage pulse which initially changes in amplitude in a polarity direction relatively in opposition to the polarity of the main voltage simultaneously supplied to the electrodes,b. said first means including circuitry to cause said pulse to thereafter change in amplitude in a polarity direction in aid of the polarity of the main voltage simultaneously supplied to the electrodes.