5
Application Examples
110
Keysight U1401B User’s and Service Guide
Bipolar Junction Transistor (BJT) Test
A BJT typically has three terminals, namely emitter (E), base (B), and collector (C).
There are two types of BJT depending on polarity: PNP type and NPN type. It is
recommended that you obtain the specific data sheet from the manufacturers. You
can also use the U1401B to identify the polarity and terminals of a BJT by
following the procedure below:
1
Turn the rotary switch to the
position.
2
Connect the red and black test leads to the positive and negative input
terminals respectively. The positive terminal will provide a positive test voltage.
3
In this example, we will use a BJT with TO-92 package as shown in
Figure 5-7
TO-92 Transistor
4
Probe pin 1 with the red test lead, and pin 2 with the black test lead. If the
measured value is
OL
, reverse the probes. If the measured value is still
OL
, you
can assume that these two pins are the emitter and collector terminals. The
remaining pin 3 is the base terminal. Always find out first which pin is the Base
terminal. Refer to
Most TO-92
transistors will
have pin 1 as the
emitter.