Sencore FE149 - Page 8

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10 100 ІК
IMPEDANCE ІМ OHMS
Figure 1
MEASURING EXTREMELY SMALL CURRENTS WITH THE ЕЕ149
Very small currents from Oto 100 nanoamps (0. 1 microamps) may be measured using
the ЕЕ149 in conjunction with a 1. 5 volt battery. Leakage currents of transistors
and diodes and leakage of paper and electrolytic capacitors can be measured with
the method below.
То make nanoamps measurements, depress the plus DC VOL'TAGE button and the
1.5 volt range button. Connect a 1.5 volt battery across the input leads; the meter
should now read full scale or slightly higher. Connect a transistor, diode or ca-
pacitor between one battery terminaland the FE149 input. Observe battery polarity
when connecting the device to be measured to obtain an accurate indication. Read
theO to . 5 DC scale of the meter and multiply the reading by 200 to obtain the current
in nanoamps. For example:
a germanium diode leakage indication is .48 .48 x 200 = 96 nanoamps
a silicon diode leakage indication is .1 . 1 x 200 = 20 nanoamps
MEASURING HIGH VOLTAGE WITH THE FE149 с
CAUTION: High voltage is dangerous and extreme caution should be observed when
making measurements. Be sure that the ground lead of the FE149 is connected to
the ground of the unit to be measured before you measure the high voltage present.
If the ground lead is notconnected, you аге merely extending the high voltage closer
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