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g) Transistor test
The transistor test is used to measure the gain factor of transistors. The gain factor is the ratio between the collector
current (IC) and the basic current (IB). An auxiliary current with a 24 kiloohm resistance (not included) is required for
this measurement. Connect this resistance between the transistor’s basic and collector terminals.
Proceed as follows to measure the gain factor:
- Turn the rotary switch to the measuring function “Ω” and the measuring range
“x10/15mA”.
- Connect the black test lead to the COM socket (6) and the red test lead to the V/Ω
socket (7).
- Zero the multimeter using the adjustment screw (3).
- Make sure that the “Vrms/Vp-p” button (9) is not pressed.
- Connect both test leads and wait until the scale indicator has stabilized. The
display should show a value of approx. 0 ohm. Zero the meter to 0 ohm using the
0 ohm adjustment knob (8) in case of deviation. If a zero adjustment cannot be
conducted, the micro (AAA) batteries are in need of replacement.
- Depending on the type of transistor at hand, connect both test leads to the measur-
ing object (transistor).
NPN: Black test lead to collector (C), red test lead to emitter (E)
PNP: Red test lead to collector (C), black test lead to emitter (E)
- Read the measured value for the gain factor from the “hFE” scale.
- If no value is shown, the transistor is measured in reverse direction or the transis-
tor is defective (interrupted).
- After measurement, turn the rotary switch to position “OFF” to turn off the multimeter.
If the transistor’s basic terminal remains open (no resistance installed), the leakage current “Iceo” between
the collector and emitter is shown. This value can be read on the “Iceo” scale using the unit “mA”.
