Abstract: An integrator circuit comprises an operational amplifier having its inverting input coupled to an input resistor to which an input voltage is supplied, and its non-inverting input coupled to a reference potential. A capacitor and a first output resistor are coupled in series between the inverting input terminal and the output terminal, from which an output voltage is derived. A second output resistor is coupled between the reference potential and the connection of the capacitor and the first output resistor. The addition of the two output resistors makes it possible to easily realize a desired integration constant with the use of a larger fixed capacitor, thereby minimizing unwanted parasitic capacitor effects. The integration constant can be adjusted as necessary by making the output resistors variable.

Abstract: A portable, X-Y plotter capable of plotting on any sized medium and work surface comprises a generally T-configured instrument transport assembly for controllably imparting a dual (X-Y) axis translation to an instrument (e.g. plotting pen) across a workpiece (paper) and controllably engaging the plotting pen with the paper during its translation. The transport assembly includes a first, generally cylindrical translation arm, which forms the top of the T-configuration and extends in a first axial direction. This first translation arm is supportable at its opposite ends on a work surface, such as a table top, upon which plotting paper is disposed. A second, generally cylindrical translation arm, which forms the vertical leg of the T, is coupled through a T-joint coupler to the first translation arm, so that the second translation arm extends in a second axial direction, orthogonal to said first axial direction. The opposite end of the second translation arm free wheels on the support surface.