Introduction The 178 Linear IC Test Fixture is a plug-in device for use with the 577-D1 or 577-D2 Curve Tracer Systems. The 577-178 combination, with the D1 Display Unit module, is designed to measure the parameters of operational amplifiers, comparators, differential amplifiers, and regulators. The D2 Display Unit may be used, but since it lacks display storage the results may not be satisfactory because of the low frequencies necessary to test many devices. The 178 Linear IC Test Fixture features a sweep generator, positive and negative power supplies, part of the vertical measuring system, a feedback loop for the device under test (dut), and switching capabilities to facilitate testing of various parameters under diverse conditions. The sweep generator provides sinusoidal output with the frequency variable from 0.01 Hz to 1 kHz. The sweep i generator output is used to force the dut output or the ; positive and negative supplies (either in-phase or out-of phase), or to sweep the dut inputs. The dc voltage levels of both positive and negative supplies are independently adjustable from 0 to 30 volts. The negative supply can be made to track (have the same absolute value as) the positive supply amplitude. The maximum current capability of the positive and negative supplies can be limited by potentiometers on the dutcard. If the load current attempts to exceed the set limits, the supply current limits and a lamp for each supply indicates the condition.