11 would best. However, you are an
electrician service engineer intending purchase new instrument, I
think balance that good-quality digital multimeter such that shown
in Fig. The fuel gauge
on motor car often indicates full, half full danger analogue dis-
play which much more informative than indication the exact num-
ber litres petrol remaining the tank.
Digital meters instruments
Digital meters provide the same functions analogue meters but they
display the indicated value using seven-segment LED give numerical
value the measurement. Red or
danger zones can indicated industrial instruments. 5.11
Digital multimeter suitable for
testing electrical and electronic
circuits.
∴ I
V
R
S
T
S
V
A
12
6
2
Ω
Measuring volts and amps
The type instrument purchased for general use the electrotech-
nical industries difficult choice because there are many different
types the market and every manufacturer’s representative convinced
that his company’s product the best.
Hi-fi equipment often uses analogue displays indicate how power lev-
els vary with time, which more informative than specific value. Modern digital meters use semiconductor tech-
nology give the instrument very high-input impedance, typically about
10MΩ and, therefore, they are ideal for testing most electrical electronic
circuits.9, lS.
Most meters using analogue scale incorporate mirror eliminate par-
allax error.Basic Electrical Installation Work
110
Let call the current flowing through both resistors and R2, shown Fig.
These meters are only accurate when used the calibrated position usu-
ally horizontally. They are
the only choice when general trend variation value observed.
.
The choice between analogue and digital display difficult one
and must dictated specific circumstances. The user must look straight the pointer the scale when tak-
ing readings and the correct position indicated when the pointer image
in the mirror hidden behind the actual pointer.
Definition
Digital meters provide the same func-
tions analogue meters but they
display the indicated value using a
seven-segment LED give numeri-
cal value the measurement. However, most instruments can be
broadly grouped under two general headings: those having analogue and
those with digital displays. Having moving parts, digital meters tend
to more rugged and, having very high-input impedance, they are ide-
ally suited testing all circuits that electrician might work his
daily work.
FIGURE 5.
Definition
Analogue meters have pointer mov-
ing across calibrated scale. 5.
Analogue meters instruments
Analogue meters have pointer moving across calibrated scale. That the point which
a reading should taken from the appropriate scale the instrument
