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VIEW

Fig.

1.

The

KD2116 consists of four

closely

matched

npn transistors arranged in a pair

of Darlingtons. All collectors are common.

Production

techniques have improved

in

the

last few

years,

however,

and

about

two

years

ago

semiconductor manufac-

turers

came out

with

linear

IC's

(am-

plifiers,

etc.) ,

which, though

they

were

still relatively

expensive compared to dis-

crete

components, found great favor in

the communications industry.

Television

and

FM receiver manufacturers immedi-

ately began using IC's in their products.

Now

IC's are

found

in CB units and to an

increasing extent in

standard broadcast

receivers.

For

the average electronics experi-

menter, most of

the

linear

IC's available

(and they are

made by almost

all

of the

semiconductor

manufacturers)

are still

too

expensive

for

wide use -though

he

appreciates their superior

performance

characteristics and

high reliability. Times

are

still changing,

however, and it is

possible that

now the experimenter's

chance to use

IC's is at

hand. RCA now

has available at

its

distributors

a

Linear

Integrated Circuit

Variety

Pack

(KD-

2117)

for just

$4.40.

The pack

contains

five TO -5 -size

linear IC's : two

KD2114

transistor

arrays, two

KD2116 dual

-Dar-

lington arrays, and a

KD2115

audio am-

plifier. With the

IC's

comes

a

booklet

describing

12 basic

starter circuits that

are

not only good

in themselves, but

will

suggest

many others.

KD2116.

This 10 -lead

integrated circuit

consists

of

four

transistors

connected

to form two

independent

Darlington

pairs as shown

in

Fig. 1. The

closely

28

matched

transistors

with emitter

-fol-

lower outputs provide

very

low

noise

and a gain

-bandwidth product

in

excess

of

100 MHz.

Typical applications

for

this

IC

include

a stereo phono amplifier, a

low

-noise differential amplifier, an

opera-

tional- amplifier driver, and

low

-level ste-

reo

and

single

-channel stages.

In the ste-

reo

phono

application,

the KD2116 can

be mounted directly on the phono arm

near the cartridge; and,

because of the

low noise, high input impedance, and

low output

impedance,

minimum shield-

ing is

required from

the

pickup to the

amplifier.

The

buffering action

of the

KD2116 also

substantially reduces losses

and

decreases

hum

pickup.

One

typical audio circuit

is

shown in

Fig. 2. This two

-channel mixer combines

two

independent inputs into a single

output.

The input impedance is

approxi-

mately

4700 ohms,

while the

output im-

pedance

is

about

10,000

ohms. Conven-

tional

volume

controls

may

be added

ahead of the circuit to adjust the re-

quired

input levels.

KD2115.

A multi -purpose, multi -func-

tion

power amplifier, this

12 -lead inte-

grated

circuit

is

designed

for

use

in

portable or

fixed communication

equip-

ment.

The circuit, shown

in Fig.

3, in-

cludes a

voltage

regulator, a buffer stage,

a differential

amplifier and

phase

split -

ter, a driver,

and a power- output,

push -

pull

stage.

Although it can be used

for

a

number

of different

functions, the typical audio

INPUTS

10K +

220K

- 9V

10

yF

+

10

NF

56K

101,F

OUTPUT

2009E

Fig. 2. The

KD2116 makes

an

excellent

two -

channel mixer useful

for

audio

systems.

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