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̶ 21 ̶
⑷
The meter pointer deflects close to full scale when the forward
current I
F
is measured. However, it hardly deflects when the reverse
current I
R
is measured.
The forward voltage of the average germanium diode measures 0.1 V
to 0.2V and that of the silicon diode 0.5V to 0.8V.
⑸
Since the maximum open circuit voltage at the low resistance ranges
is 3V (12V at X 10k range), it is possible to light up an LED having a
forward voltage of more than 1.5V and measure forward current I
F
as
well. The reading on the LI scale indicates the forward current I
F
at
which the LED lights up. The reading on the LV scale also indicates
the forward voltage V
F
For testing a large LED use the X1 Ω range. For a smaller LED
having less than 10mA IF use the X10Ωrange.
Diode Test
Fig.4
I
R
<
<
I
F
N(-COM)
I
R
I
F
P(
+
)
×
10
×
1
×
1k
Summary of Contents for KEW 1109
Page 1: ...INSTRUCTION MANUAL ANALOGUE MULTIMETER KEW 1109S ...
Page 30: ... 28 PCB Component Layout Drawing Fig 11 ...
Page 32: ... 30 CIRCUIT DIAGRAM ...
Page 33: ... 31 MEMO ...
Page 34: ... 32 MEMO ...
Page 35: ......