Operating instructions

University of Saskatchewan

Electrical Engineering Laboratory Equipment Manual

Tektronix Curve Tracers

There are two models of Tektronix curve tracers available in 2C80: two Tek 575

Transistor Curve Tracers and one Tek 577 Curve Tracer. These instruments greatly

speed the checking of npn and pnp transistors, as well as diodes.

This document will not supply you with pictures of the front panels of these

instruments, since they are too difficult to reproduce here. Another point to consider is

that these instruments will be used only rarely, so a detailed operating instruction is not

necessary. However, the instructions contained herein will be sufficient for you to set

these instruments up to measure the characteristics of npn and pnp transistors, and

diodes as well.

The curve tracers are really rather simple instruments that are tailored to plot the

vs. V

characteristic of a transistor for different base currents, I

. To do so, circuitry

within the instrument monitors the collector current as the collector-emitter voltage is

increased for a specific value of base current. The I

vs. V

characteristic is plotted,

then the base current is stepped to the next value and the process is repeated.

Tektronix 575 Transistor Curve Tracer

The 575s are the oldest curve tracers and their controls are just a little easier to

navigate than their newer counterpart, the 577.

At the bottom right corner of the instrument you will find the power switch.

Directly under the display are four knobs that control the focus, intensity, astigmatism

and scale illumination of the display.

To the immediate right of the display is the vertical current or volts/div knob.

Depending upon its position, it can display the base volts or collector current along the

vertical axis. The vertical position control is located underneath this knob.

In the top right corner is the horizontal volts/div knob. Again, as with the vertical

knob, it can display the collector or base volts along the horizontal axis. The horizontal

position control is located underneath this knob.

Under the display are the collector sweep controls. The peak collector voltage

may be set to a 0-20 V range or a 0-200 V range by a knob on the left. Whatever range

is chosen, the collector peak voltage is set by the fine adjust knob beneath the range

knob. To the right of the range knob is a polarity knob where you select either – (pnp)

or + (npn). Under that you will find a knob that selects the dissipation limiting resistor for

the sweep.

To the right of the collector sweep controls are the base step generator controls.

There are four switches/knobs across the top of this area that control the following: