OE 3008BL
CAT.I DIGITAL MULTIMETER
Testing the diode
1. Connect the black test lead to the "COM" terminal and the red test lead to the "V
Ω
mA"
terminal.
(Note: The polarity of the red cable is positive "+".)
2. Set the range selector switch to the position
.
3. Connect the red test lead to the anode of the diode under test and the black test lead
to the cathode of the diode.
4. The display shows the approximate forward voltage drop of the diode. If the connec-
tion is reversed, only the number 1 is shown on the display.
Note:
Before testing, please disconnect the circuit to be tested from any power supply and
fully discharge any capacitors.
Measuring the gain of a transistor
Unlike a diode, the transistor has 3 connections. There are 2 types of transistor "NPN" or
"PNP" which have the same operating principle.
The current Ie at the output of the emitter = current Ib (base input) + current Ic
(collector input).
The ratio between lc and Ib is called the transistor gain.
• Set the selector switch to the hFE position.
• Insert the emitter (E), base (B), collector (C) of the transistor to be tested into the
appropriate inputs (one side for a transistor).
inputs (one side for a PNP transistor and the other for an NPN transistor).
• Read the hFE value (current gain) of the transistor.
NOTE:
If you do not know the type of transistor, choose either NPN or PNP. If the display
shows (negative) the choice is wrong, or the transistor is defective.
Test current Ib
10
µ
A
VCE = test voltage
between
collector-transmitter
Test voltage VCE
2.8 V
Gain
0 to 1000
