Tektronix 575 Curve Tracer
This Curve Tracer, S/N 001946, was donated by John Roe on 9-June-2021.
This Curve Tracer is used to determine the voltage/current curves for transistors and diodes. It was produced from 1957 to 1972, and the active devices inside are vacuum tubes. A transistorized version of the Curve Tracer, the 576, was introduced in 1969.
Several of the machines under restoration at the RICM, like the DEC PDP-9 and the WANG LOCI-2, use transistors and diodes that have no known modern substitute. We can use this Curve Tracer to determine the electrical characteristics of the transistors and diodes and compare them to potential substitutes. It will also be interesting to compare good transistors to partially failed transistors to see what characteristic has changed.
The vertical scale on the display can be either the voltage on the base of the transistor under test, or the current going through collector of the transistor under test. The horizontal scale on the display can be either the voltage on the base of the transistor under test or the voltage on the collector of the transistor under test. There are two sections of the curve tracer that control the current on the base and voltage on collector of the transistor under test. The Base Step Generator can be configured to generate a stairstep pattern of currents with 4 to 12 steps in the pattern. The current per step is selectable from 0.001 mA to 200 mA per step, and a selectable Series Resistor is used to limit the current on the base so the device under test is not damaged. The Collector Sweep is used to sweep a voltage across the collector. The two sections are synchronized so that the collector voltage sweeps once per base current stairstep.
We will post some pretty pictures of transistor curves as we learn how to use this device.