Metra Electronics DAT Combo Instrukcja Użytkownika Pobierz pdf (Strona 69)

troubles

with

an

AC ammeter.

The

ammeter

described

above

will

work

on

most

radios,

audio amplifiers,

and

TV

sets.

Do

not

use

it on

irons,

toasters,

or other

high current

de-

vices. To make this

meter

more

useful

in

checking

line -cord

powered

devices

an

adapter

(shown in the photographs)

was de-

veloped.

Since there

was no

room

in the

meter

box

for

an AC receptacle

or

fuse holder

I de-

cided

to make an

additional

box that

could

be

easily fastened to

the meter

box. The end

dimension of the

meter

box was

4- inches

wide

by

3-

inches high.

A

box 2-

inches deep

that

would

match this

would

be

great,

but

none

are available.

The nearest

standard

-size

box is 4 x 2' /a

x 2-

inches or you

could cut

down

a 3

x 4 x 5 -inch

box to

match the

meter case.

An AC socket

and

plug

are

mounted

on

the front of

the

box -on

the

top

is

a

fuse holder and

two 5 -way

binding

posts.

The

back of this

box

has two banana

plugs that

mate

with two

banana jacks

mounted

in

the

meter

box.

These banana

plugs and

jacks just

hold

the two

boxes to-

gether

and do not

carry the

meter current.

Be

sure and

use an

instrument fuse

to pro-

METER

(MI)

TERMINALS

R2

TO JI

iTO

J2

RI

SI

STANDARD

METER

AC

PLUG

You don't

need

to

resort

to a

lot of

figuring

if you

use

the

cut-

and

-try

method

of

shunt

design.

Just

connect

the

two

meters

in series

and

increase

the

resistance

of

the shunt

until

meters

indicate

the

same.

Refer

to

the

text.

tect

the

meter

-they

are

faster

than

a

con-

ventional

fuse.

How

It Works.

The

device

to

be

tested

is plugged

into

the

AC

socket.

A jumper

cord,

with banana

plugs,

connects

the

adap-

ter

and

ammeter

through

the

5 -way

binding

posts

on each

box.

This

connection

puts

the

meter

circuitry

in series

with

the fuse

and

AC

plug.

An

AC

cord

with a male

plug

on

one

APPROX.

IAMP

FOR

EACH

100

WATTS

P3

J7

All

circuitry

inside meter

case (left)

is

on

phenolic

board

that mounts

directly

on

meter

terminals.

Tapered

end of

phenolic board

is to give

better clearance

for

leads to J1

and

J2.

If you

start

with a

larger case, adapter

can be

built in, eliminating

J3, J4,

J5 and J6

as

well

as

M

and

P2. The 5 -amp

fuse will

not protect

M1 if shunt

resistor

should

open

up.

FEBRUARY-MARCH,

1967

75

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