The Tektronix Type 545A Oscilloscopes are wide-range general-purpose laboratory instruments. The Type 545A provides accurate measurements in the dc to 30 mc range. The instrument can be operated with any Tektronix letter- series plug-in unit to satisfy the requirements for virtually any application. Special circuits incorporated in the Type 545A Oscilloscope permit an accurate, continuously variable delay in the presentation of the sweep from 1 microsecond to 10 seconds after receipt of a triggering impulse. This feature permits observation of a small portion of the normal sweep, accurate measurement of waveform jitter, precise time measurements, as well as many other uses.