Abstract: A synthesizer for multiphase waveforms is disclosed which is useful, for example, in open and closed loop control of a two-phase induction motor, such as for a magnetic recording disk spindle, utilizing a plurality of bistable elements, two for each phase, to control output power drivers. A single clock pulse counter is employed to time the setting and resetting of each bistable element according to some predetermined pattern controlled by combinational logic which presets the counter to proper values at appropriate times in response to external stimuli, such as speed feedback control and start-stop control.

Abstract: A simple and compact tool for use with aircraft spark plugs to reset the spark gap, which enables a person to hold the spark plug to the tool, hold a gauge to the spark plug, and squeeze the electrodes of the spark plug to set the gap, all under field conditions. The tool includes a pair of bars pivotally connected at one end and a nut fixed to a first of the bars to loosely hold a spark plug, the nut having a cut-away portion to permit the second bar to move over a spark plug held by the nut, and the second bar having a recessed edge which can move against an electrode of the spark plug to bend it.