Abstract: Aspects of a transport dolly for repositioning a drive unit are described. In one embodiment, the transport dolly includes a base frame, an elevated handgrip bar, and a wheel lock assembly that locks at least one jack wheel of the drive unit into an engaged position for manual displacement of the drive unit using the elevated handgrip bar. The transport dolly may be relied upon to assist an individual with manual movement of the drive unit, by engaging and locking one or more jack wheels of the drive unit into a position which lifts the drive unit off the drive wheels of the drive unit. Once the jack wheels are engaged and locked in position, the drive unit may be more easily repositioned manually.

Abstract: The invention provides a monolithic Y-bit resistive-ladder type digital-to-analog converter (DAC) having a unity gain inverting operational amplifier as an input buffer to the resistive ladder segment of the DAC. The reference voltage is applied to the input buffer amplifier. Optional bipolar operation is provided by applying a non-inverted reference voltage to the output of the resistive ladder segment of the DAC through a scaled resistance. Analog ground current cancellation is provided by a secondary X-bit R-2R ladder (where X Y) with the non-inverted reference voltage applied to it. The secondary bit ladder is switched in parallel with the top X bits of the main ladder, thereby supplying or sinking roughly the same amount of current as the X most significant bits of the main resistive ladder, but with opposite sense.