Keysight U1401B, Руководство пользователя и сервисное руководство

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5 Application Examples
116 Keysight U1401B User’s and Service Guide
Junction Field-Effect Transistor (JFET) Switch Test
A JFET typically has three terminals, namely drain (D), gate (G), and source (S).
There are two types of JFET depending on the channel type: p-channel and
n-channel. It is recommended that you obtain the specific data sheet from the
manufacturers. You can also use the U1401B to identify a JFET 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 JFET with TO-92 package as shown in
Figure 5-10 .
Figure 5-10 TO-92 JFET
4 Probe pin 1 with the red test lead, and pin 2 with the black test lead. Then
reverse the test leads and obtain the reading. If both readings are
<
1 k
Ω
, you
can assume that these pins are the drain and source terminals. The remaining
pin 3 is the gate terminal. Always find out first which pin is the gate terminal.
Refer to Table 5-7 on page 117.
Most TO-92 JFET
will have pin 1 as
the drain.