Marantz 5220 User Manual download pdf (Page 87)

Hobby

Scene/

By John McVeigh

DIMMER RFI

Q. I replaced

several of

my wall

switches

with triac dimmers, but

now

experience severe interference to

AM broadcasts.

I tried

0.1-pF

capacitor,

which

reduced

but did not

eliminate the noise.

How

can

I lick

this problem?

-William

Conover,

Clinton, TN

The fast

switching

action

thyristors

produces

voltage

and

cur-

rent

waveforms with

abrupt

on and

off

transitions,

which

contain

loads of

harmonics extending

into the

hf re-

gion. A lowpass

filter will take care

the

harmonics without defeating

the

INCANDESCENT

METAL

BOX

BULB

f- 7

I 11111

/7-

.1y..7

EARTH

GROUND I

TyF

VAC

IOOYH

purpose

the dimmer. Construct

two

low

-pass filters

(one

for each

side

of the

line) from 100

-pH

coils and

0.1

-pF, 200

-V ceramic capacitors.

Mount the filters

and

the dimmer

in-

side a

metal

box, and bond

the

box

a good earth ground. That

should

clear up your

reception.

.IyF

IOOyH

117

DIMMER

CIRCUIT

DIGITAL IC DATA

Q. 1 am

looking for a handbook on the

7400

series of

digital integrated cir-

cuits.

Is there any volume out

that can

serve as

a basic reference guide?

-Galen

Tackett, Newark, CA.

The 7400

Series

Pinout Handbook

will

probably

help

you. It includes

connections,

functional

specs,

truth

tables, and a

cross -reference.

It's

available

for $2.95 plus $0.30

post-

age

from

IMS Associates,

1298

14th

St., San

Leandro, CA 94577.

EUROPEAN /US AC CONVERTER

Q. I am serving with the Canadian

Armed

Forces

in Europe and have

purchased several appliances which

I want to take home with me. Is there

a simple way to convert the 50 -Hz,

220

-V ac power

60 -Hz,

110

-V ser-

MARCH 1976

vice we

have in

North America?

-Keith L. Webber,

Lahr,

Germany

simple

2:1 transformer

will take

care

the

voltage problem, and

works both

ways.

you want

con-

vert

110 V

220 V, take a transformer

like the

Thorardson Type

23V74,

at-

tach a power

plug to the

secondary

and a

receptacle to the

primary.

When

110

applied

to the

"secondary,"

220

V will appear

across

the

"pri-

mary." To

step

down

220 V

110 V,

reverse this

procedure.

It is

not an

easy job,

however, to convert the

50 Hz

60 Hz line frequency

vice versa.

You

would

have to

rectify

the

to dc,

and

then use a

dc/ac

transistor

con-

verter

running at

the desired

line fre-

quency.

sample

circuit

was shown

PE, 5/69, page

65.

We've had

many

inquiries

about

these dc/ac

circuits,

but

they all

share several

disadvan-

tages.

They tend

to be

inefficient,

re-

quire

bulky, expensive

transformers,

ones you

have to

roll for

yourself.

Most

them

have

limited power

capacities,

and

their outputs

are

square -wave

ac.

This

makes them un-

suitable

for use

with

induction

motors,

refrigerators,

air

conditioners,

etc.

v>I

m,ï,,ftmeatte

Introducing

the

Phase

Linear

System

200

A complete

home

stereo system

built

around a

Phase Linear amplifier

is now

within the

reach

every

serious

lis-

tener. The development

of the

new

Phase Linear

200 power amplifier

makes it possible.

In combination

with

the

advanced

2000

preamplifier,

the

200

provides the

nucleus of a

fine,

medium

-powered stereo

system

with

lower distortion,

wider dynamic

range,

faster transient

response

and greater

flexibility than

a comparable

receiver

based

system

- at

a surprisingly

reasonable cost.

With a pair

of quality

bookshelf

speakers

and a good

turnta-

ble, a

Phase

Linear 200

system

can be

assembled

by your

dealer

for around

$1,000 -a

fraction of the

investment

many

veteran audiophiles

with sophis-

ticated systems

amplified

Phase

Linear.

You

might

well start

near

the top.

The

new Phase

Linear 200 power

amplifier

is a

handcrafted,

reliable

amplifier

with outstanding

sonic

per-

formance

the

tradition

of the

famous

700B and

400

models.

Power output

105 watts per

channel,

minimum

R.M.S.

8 ohms

from 20

Hz to 20

kHz, with

than

.25% total

harmonic

distor-

tion.

Light emitting

diode

displays give

instantaneous

display

power

for

each

channel.

Hum and

noise: 100 dB

below

rated power.

The Phase

Linear

2000 preamplifier

one of

the quietest

preamps

ever

made.

Signal to

noise

ratio

below

10 mV and

total

harmonic

distortion

0.1%.

Variable ambience

injection

circuit

recovers

music

lost

with

most preamps.

,Ata4e

Witeeez

The

Powerful

Difference

Manufactured

the

U.S A. Distributed

Canada

by H Roy Gray, LTD.

CIRCLE

ON FREE

INFORMATION

CARO

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Marantz 5220 User Manual Page 87

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