Elenco Electronics MO-1251 Manual do Utilizador descarregar pdf (Página 17)

100

EQUIPMENT

REPORTS

Sencore LC102

Capacitance /Inductance

Meter

Check capacitors

and

inductors

the

fast

and easy

way!

CIRCLE 14

FREE INFORMATION

CARD

IT SEEMS THAT AS

CIRCUITS GET

and

complicated, testing

components and

troubleshooting

in general

get that

much

easier.

For

example, take the LC102 "Auto -Z"

meter from

Sencore

(3200 Sencore

Drive,

Sioux Falls, South Dakota

57107). It can give

you a precise

capacitance or inductance mea-

surement

displayed

common

terms at the

touch of a button, and

even has

an automatic test to tell

you whether

a capacitor or

induc-

tor is

good or bad. Its

capacitance

range is from

0.1 pF to 19.99 F,

and

its inductance

range is from

0.1

µH

to 20 H, and

both can be fully auto -

ranged. It

can also

be operated on

IEEE 488

bus. Another good fea-

ture is that it

can be powered from

optional rechargeable

lead

-acid

battery, making the LC102 well

suit-

for field

use.

Besides

the obvious, such as

checking a capacitor's value,

the

LC102

can test

for

such things

leakage, ESR (Equivalent

Series

Resistance),

and dielectric absorp-

tion. ESR is the real resistive

com-

ponent of a capacitor's

impedance. Dielectric absorption

is the inability of a capacitor to

fully discharge, and the LC102 pro-

vides an

automatic

test for that. It

also provides

accurate "true in-

ductance" test, as

well

as a "ring-

ing test"

to check coils, deflection

yokes, switching power supply

transformers,

and all

other types

non

-iron

core

inductors.

To determine

a capacitor's value,

the LC102

measures

one RC time

constant while

charging the

capac-

itor

under

test to

volts.

That

basically means

that the LC102

measures

the rate

at which

a ca-

pacitor

charges

under known con-

ditions. An inductor's

value

determined

by applying

a chang-

ing current

to the inductor

under

test and measuring

the produced

EMF.

In plain

terms, an inductor

has a tendency

to resist

changes in

current, and the

strength at which

it resists

those

changes corre-

sponds to

the

inductor's

value.

The

properties

of an inductor

are such that

a current (or wave-

form) flowing

through

the induc-

tor

will

continue

to flow even after

the current

source is removed.

The

current continues

to flow (or

the

waveform

continuously

repeats it-

self) until all

its

energy is

dissi-

pated

by the

inductor

in the form

heat

(the waveform

repeats it-

self as its

magnitude gets in-

creasingly

smaller until

the wave-

form "flattens,"

or dampens

out

completely -that is

known

ring-

ing). Therefore,

the ringing test is

done

by applying a pulse

to the

inductor

under test, and then

counting

the number

of ring cy-

cles

before the

pulse dampens to a

preset

point.

Good

or bad?

One of the

more interesting

fea-

tures of the LC102 is that it can

store a

set of component param-

eters

for

either a capacitor or an

inductor in memory,

and then

per-

form

an automatic go

/no

-go test

for

any of those parameters. The

test

reading

and "good"

"bad"

will

be displayed on the

LCD when

a test

button

pressed.

A large

number

the

same components

can be quickly checked

by con-

necting them

one

at a time to the

test leads

and selecting the desir-

test.

The go /no -go test is performed

first

pressing the appropriate

component

-type button on the

front panel

of the

LC102.

The nu-

merical value

of the device is en-

tered

followed

by a

multiplier (pF,

µF, mH, µH,

etc.).

The

tolerance of

the device is then

entered as

fol-

lows: Al-

to 3 -digit number from 1

to 100 is

entered,

followed

pressing

the "

+ %"

button.

Then

2 -digit

number is entered, fol-

lowed by pressing

the " %" but-

ton. The voltage rating,

working

voltage

(from 1 to 999.9) of the ca-

pacitor to

tested is

entered,

fol-

lowed

by pressing the "V" button.

When

the capacitor -leakage but-

ton is pressed,

the

working voltage

is applied

to the capacitor under

test.

Therefore,

you

have to

careful not to touch

the test -leads

during that test.

For safety's

sake, two

red LED's

on the front panel

are there to

warn you

-one to

indicate

the

presence of

anything above

volts

being applied to the test

leads,

and the other to indicate

that the internal

discharge circuit

has failed.

(When

performing

the

leakage

test, ultra -large capacitors

may cause the test -lead fuse to

blow,

leaving

the capacitor

charged

with

a potentially dan-

gerous voltage.)

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 99 100

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