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“
Æ
%” reference value measurements, “MIN/MAX” value capture,
“TIME”, “REC” record measured value, “RCLL” measured value recall,
“LMT” comparison function (VC 670 only) and “PH” peak value mea-
surement (VC 650 and VC 670 only). These sub-functions are descri-
bed in more detail in section 5.12.
5.9 Transistor test
Attention !
The transistor socket is not protected against overload.
To measure the hFE parameter (amplification) of a transistor, proceed as
follows:
a) Switch the measuring instrument on. The initial configuration is
always AC voltage measurement in “AUTO” (automatic range selec-
tion) mode. Now press the „H • hfe •
• Logic“ button three times.
The measuring instrument switches to transistor test, recognisable
through the symbol “hfe” in the bottom left of the display.
b) The bar graph beneath the measured value is active during measure-
ment, being similar to an analogue indicator with a faster reaction
time. The bar graph operates as a trend indicator.
c) Place the transistor to be tested into the measurement socket. Obser-
ve the pin configuration (e.g. c-b-e) of the item to be measured
(given in transistor comparison tables/lists).
Note the following:
- some types of transistor include base-emitter resistors, which can
distort the measurement result.
- the measured hfe value is not absolutely accurate. It only confirms
whether the transistor is working or not. The actual amplification of a
transistor depends on its working current. This multimeter can deliver
a base current up to 10 uA with a Vce of 2.8 V. The collector current
flowing during measurement is captured and from this the hFE value
is calculated.
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d)
Connect the black test lead (test probe) to the circuit or signal gene-
rator earth and the red test lead (test probe) to the signal to be mea-
sured.
Attention!
It is essential to observe the maximum input levels! Do not connect any
voltages greater than 250 VDC or VAC rms max. Life can be endangered
by coming into contact with voltages greater than 25 VAC or 35 VDC.
Do not switch to another measuring function or to another range
during measurement.
Switching under voltage (high energy) can cause a disconnection arc,
which can irrevocably destroy the printed circuit tracks inside the mea-
suring instrument. In addition, life may be endangered as a result of
damage to the measuring instrument.
Frequency measurement is not possible with voltages smaller than
approx. 50 mV rms (measured at 1 KHz).
Notes!
1. During frequency measurement, in addition to the measured value
and the bar graph, in the bottom right sub-display (“small” display)
the level (amplitude) of the measured voltage in VAC rms is also dis-
played; in addition the 1/2 period (1/2 reciprocal of the frequency) of
the signal being measured (up to 100 kHz) appears in the left sub-dis-
play. Note the following table.
2.
Selectable special functions
The following sub-functions, according to multimeter model, are
selectable by means of the “ENTER MENU” button:
AUTO
Hz
0
+10
+20
ms
mV
