Automatic electrical curve tracer - uses pulse-width modulator and switching to set knee-point coordinates of polygon

摘要

The curve tracer comprises a selection circuit to which the knee-point voltages are fed via potentiometers. The input voltage (Ue) of the curve tracer is also fed to this circuit which compares this with the abscissae (Ueo-Ue7) of all knee-points (Ko-K7). The input is also taken to a pulse-width modulator which has a control unit which converts the input voltage into a switching signal whose mark-space ratio varies with the amplitude of the curve tracer input voltage. The switching signal is fed to a changeover unit (32) and controls coupled switches. The output from these switches is smoothed (33) and the final output is the output voltage (Ua) of the tracer. The curve tracer produces the required curve by successive approximations to straight line sections and to determine the relationship between input and output voltage, needs only to set the coordinates of the individual knee-points of the polygon course.