CURVE TRACER SET-UP
Refer to Figure 4.
1. Connect the plug of the power cord to a 117-
volt, 50/60-Hz ac outlet.
2. Set the STEP SELECTOR switch and VERTICAL
SENSITIVITY switch to the T marker. This pro
vides a good starting point for all small signal
transistors and is low enough to prevent dam
age, even to very delicate transistors. It is rec
ommended that these controls always be placed
fl\
CONNECT THE POWER PLUG TO
A
\!_)
117 VAC 50/60 HZ OUTLET.
®
®
TURN UNIT ON. TO CHECK AC (AL
WAYS
RETURN TO
11
0
11
BEFORE
INSERTING A TRANSISTOR FOR TEST.
ROTATE STEP SELECTOR 8i V ER
T ICAL SENSITIVITY CONTROLS TO
FAST SET-UP MARKERS ( .,_ ).
in this "fast set-up" reference position before
connecting transistors for test.
3. The SWEEP VOLTAGE control may be turned
clockwise to check the AC outlet; the pilot lamp
will light indicating that the unit is energized.
Always return this control to "O" before insert
ing a transistor for testing.
D
The semiconductor curve tracer is now ready
to be connected to the oscilloscope.
b
�a
[[]
·Figure 4. Initial Curve Tracer Set-Up
OSCILLOSCOPE SET-UP AND CALIBRATION
An oscilloscope must be used with the semicon
ductor curve tracer. Any 3-inch or larger general
purpose oscilloscope with external horizontal input
is satisfactory. The sweep circuits of the oscilloscope
are not used-only the horizontal and vertical de
flection circuits. The oscilloscope should have de
coupled circuitry; ac (capacitor) coupling produces
trace shift that will distort the display of curves.
High-frequency bandwidth, however, is unimportant,
just as long as it reaches lOKHz or greater.
To interpret meaningful results from the data
displayed on the oscilloscope, the vertical divisions
of the
gr
aticule must accurately represent the current
thru the semiconductor being tested, and the hori
zontal divisions must accurately represent the sweep
voltage applied to the semiconductor being tested;
that is, the oscilloscope must be calibrated. This is
easily accomplished using the calibration source
built into the curve tracer.
Vertical
Calibration
The curve tracer requires that the oscilloscope
vertical gain be set for I volt full scale sensitivity
(IO divisions of the special graticule). Once set the
display is accurately calibrated for all ranges of the
VERTICAL SENSITIVITY switch on the curve tracer.
An accurate (+3%) I-volt p-p source is available at
the base (B) jacks of the curve tracer when the STEP
SELECTOR switch is placed in the .2 VOLTS PER
STEP position. The voltage steps from O to l volt in
5 steps of 0.2 volt each (6 steps if O volts is counted
as a step), resulting in a series of six vertical dots
on the oscilloscope screen. The vertical gain should
be adjusted so one of the dots coincide with every
second division.
A step-by-step procedure follows (refer to Figure 5)
l. Place the special graticule over the screen of
the oscilloscope; cut it, if necessary, to fit on
oscilloscopes without camera mounting studs.
2. Connect a test lead from the G (
gr
ound) jack of
the curve tracer to oscilloscope
gr
ound.
3. Turn on the curve tracer and oscilloscope.
4. Set the oscilloscope for external horizontal oper
ation, but do not apply a horizontal input at this
time. The horizontal input may be grounded if
desired.
5. Adjust the oscilloscope horizontal and vertical
centering controls, if required, to place a dot in
the approximate center of the screen. Do not
allow a spot to burn the CRT.
6. Connect a test lead from one of the B (base)
jacks of the curve tracer to the vertical input
of the oscilloscope. If the left B jack is used, the
SOCKET switch must be in the LEFT position,
and if the right B jack is used, the SOCKET
switch must be in the RIGHT position.
5
