Metra Electronics DAT Combo Manuel d'utilisateur télécharger pdf (Page 71)

Flua

TAPE-GLIDE

CU

:nil

by

Robert

S.

Havenhill

i

Constructing

a

unit

with

no

springs to adjust

and

no

relay contacts

to pit or

stick

is

possible

if you

switch with a

regular

unilateral

SCR

wired across

a diode

bridge.

Just

think about

it!

I he next time you

shoe color

slide, of

our last

vacation you

can

sit on your

duff

and enjoy

a cool,

mixed

drink

while

your

tape

recorder

does

the

work.

A rich,

clear narration

prepared

in

advance

patters

out in step

with changing

slides

without any effort

on

your

part.

Your

guests

will be entertained

as

well as

curious

about that

gadget you

call

the

Tape -Slide

Synchronizer.

The

Tape -Slide

Synchronizer

is an elec-

tromechanical

device

which

automatically

actuates

the

slide- changer

mechanism

at the

exact

instant

dictated

by

the

commentary

on

the

magnetic

recording tape

-thus

assuring

perfect

synchronization

of com-

mentary and

slides

at all

times.

A

taped

slide -show

commentary

has a

number

of

advantages

over live,

off

-the -cuff

commen-

tary.

One

advantage

is that

important

facts

(that

are

hard to come

by)

will not

be for-

gotten on

successive

showings

as time goes

by.

Another advantage

is that

the

show

need

not

he

postponed

if your

voice

goes

had the

night of the performance.

You

can

sit

hack. relax and

enjoy

yourself.

(Don't

forget that

drink!)

O

Former

head of

Electronic

Research

Laboratory

and

Director

of

Product and Service

Laboratories. St.

loseph

Lead Co.,

Monaca.

Pa. Now

retired

FEBRUARY

-MARCH, 1967

Early units

were

difficult

to use.

Some

required

conductive

marks

to

he placed

on

the

tape,

others

used

a high

-level audio

signal in the

sound

track

(which

was

ob-

jectionable

as

it could

be

heard).

In

order

to

overcome

the

objection

of the

noise

from

the

sync signal,

one unit

operated

on the

complete

absence

of

sound on the

tape.

A

four -second

(or

longer)

silent

period

would

activate

the

slide-

changer

mechanism.

This

system

was

workable

with monaural

tapes

but it

was difficult

to record

the

commentary

without

pausing,

thus

causing

unwanted

slide changes.

Some

success

was also

had

using inaudible

(ultrasonic)

sync

signals.

For Stereo

Tape

Recorders. With

the

advent

of

the 1%+, o-

and tonr

-track stereo

-tape

record and

playback

equipment

the

disad-

vantages of

the early

units

were automati-

cally eliminated

as

the

commentary

could

be recorded

on one channel

and

the

sync

signal

on the

other. On

playback

the sync

signal

would

operate

the slide

changer

via

the

switch

in the synchronizer.

But

even

%ith

thi,

there

were

relay

contact

problems.

A Unique

Circuit.

This

Tape -Slide

Syn-

chronizer

is solid

state.

Using

the unilateral

SCR

(silicon

-controlled

rectifer) alone

will

pass only

one half

of the

AC (sine

wave)

power

-still

requiring

a

relay to

switch

on

77

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