Tektronix 2236 User Manual

2 U
Operating Procedures - 2236 Operators
7. To select the desired gated measurement function
( frequency
,
period
, width
, or
totalize ) , set
UPPER
FUNC
TIONS - LOWER FUNCTIONS switch to IN , and press in ei
ther FREQ , PER , WIDTH , or TOTALIZE ( FREQ and PER )
buttons
2. Connect the multimeter leads across the unknown re
sistance or across
the
semiconductor
as indicated in
Table
4-1 . The diode detection circuitry will be activated only when
the
readout displays
the
message “ OPEN
”
before
the
multimeter leads are connected across the device under
test
.
8. Rotate the B TRIGGER LEVEL control counterclock
wise to the midrange position , then adjust the control for a
stable
display .
3. Read the resistance value or the forward voltage drop
of the device on the readout .
9.
Observe that the
intensified zone
moves
,
covering ex
actly the interval that the CTM is sampling .
Determining
Semiconductor
Leakage Current
The Multimeter performs resistance measurements with
a voltage divider technique . A reference voltage of approxi
mately +2.5 volts is applied through an internal precision
resistor ( reference resistance ) to the Multimeter + ( positive )
connector
(
see Figure 4-9
) .
10. Read the measurement on the readout .
MULTIMETER MEASUREMENTS
The unknown resistance is calculated from the following
formula .
Resistance and Semiconductor Junctions
terminal
Unknown
Resistance
reference
VI
X
resistance
+2.5
volts
V.
terminal
C
Before making resistance measurements ensure that the
readout
displays the message
“ OPEN ” . If the
device under
test is a linear resistance the CTM will display that resis
tance on the readout . If the resistance is a nonlinear device
( semiconductor ) the CTM will automatically enter into the
junction test mode and display the message " diodE ” on the
readout and at the same time generate an audible tone .
After a brief moment the CTM will display the forward volt
age drop of
the
semiconductor on the
readout .
The red lead
sources the measuring voltage ( +2.5 V in series with 1 k.2 ) .
To measure resistance or forward voltage drop of a semi
conductor
use ,
the
following
procedure
:
1. Set UPPER FUNCTIONS - LOWER FUNCTIONS
switch to IN and press in the 2 button .
A Typical semiconductor will have a reverse leakage
current - vs- reverse voltage drop as shown in Figure 4-10 ) .
Observe that the typical semiconductor leakage current is
relatively constant as the reverse voltage drop increases .
باب
To measure the reverse - leakage current , perform a nor
mal resistance measurement with the Multimeter + ( posi
tive ) connector connected to the cathode of the device
( reverse biased )
.
U
Table 4-1
Multimeter Connections to
Forward Bias Semiconductors
Typical
Forward Drop
(
volts )
Semiconductor
Red Lead
Black
Lead
Silicon Diode
Anode Cathode 0.65
V
Silicon NPN Transistor
Base Collector or Emitter
0.70 V
Silicon PNP Transistor
Collector or Emitter
Base
0.70 V
N Channel Fet Gate
Drain or
Source
0.80
V
LED
Anode
Cathode
1.5 to 2.0
V
4-12
L

Tektronix 2236 Specifications

General

Brand	Tektronix
Model	2236
Category	Test Equipment
Language	English