Epson L90P - TM Two-color Thermal Line Printer Manual de usuario descargar pdf (Pagina 28)

O

KD2114

O

0 0

02

o

o

SUBSTRATE

TA

B

BOTTOM

VIEW

10

Fig.

5. The KD2114

also

contains four npn

transistors,

arranged

as an

isolated

pair

and a Darlington.

Each transistor

of

the

Darlington

can be used independently

when

certain

external

circuit changes are

made.

The

amplifier requires

an input

of

about

45 millivolts

to

drive

to full output.

Frequency

response

is

as good

as

the

output

transformer

and

speaker

will

al-

low,

and

noise is very low.

This

amplifier

makes

an

excellent

gen-

eral-

purpose

audio system

for the

bench

when

working

with projects

that require

some

form

of

audio amplification.

It

can

be used

to test

the front

end

of a circuit

before

the regular

audio

amplifier

is

built. In

strong

signal

areas,

the ampli-

fier

can

be

driven by

a crystal set.

KD2114.

The

four

active

devices in

this

integrated

circuit

(Fig.

5) are

two

isolated

transistors

(Q1

and Q2) and

two

transistors

(Q3

and Q4) with a

base-

emitter

common connection.

The

four

transistors can be used

almost in-

dependently if

terminal

2 is

at either

a.c.

or d.c.

ground so that Q3

can be used

as

a common -emitter

amplifier and Qç

as

a common -base

amplifier.

The

pres-

ence

of

Q3

does not

inhibit the use of

Q4 alone

in

a

large number

of circuits.

Applications

of the KD2114

are

many :

as

a

very -wide

-bandwidth

video

ampli-

fier (

upper

3 -dB point can reach 30

MHz) ;

as

an

r.f.

amplifier for the fre-

quency range

between 2 and 100

MHz;

as

an

i.f.

amplifier

with 30 -dB

gain

at

1

MHz;

or

as a class B audio amplifier

delivering

about 40 mW.

A Wireless

Microphone.

The circuit for

a good

application of

the

KD2114 is

shown

in Fig.

6.

The

wireless

microphone

can transmit

on

any clear

spot

in

the

88 -to-

108

-MHz commercial FM

band

and

has

a range

between 50 and

150

feet

CI

25I+

RI

270

n

R5

10K

PARTS LIST

l:1 0-volt

transistor radio

balle,

(1 -25 -µF, 6 -volt electrolytic capacitor

('' 200

-AF.

6-volt electrolytic capacitor

(i 2U

-pl,

l0 -volt

electrolytic capacitor

l'd

15 -pl' silver mica capacitor

('i-

0.001-µF,

25-

ol!

capacitor

-0.1

-pi-, 25-volt capacitor

(T i- ill

-pF

trimmer capacitor

ICI Integrated circuit - R('.I K1)211-I)

11-- I'bono jack

1.1

.See

text

R1- -270 -obm

R2 150.000

-ohm

R."

22.0(1(1

-ohm

R4-

12(10

-ohm

Rn 8200 -ohm

R; - -68

-obnr

RR-

-310 -obm

R n

-6800 -ohm

:I11

In' I _

L'a!!

R5- 10,000 -ohm miniature potentiometer

S1 -S.p.s.!. switch ,

se

text

lieue. - -- Plastie

case

//tarry Davies

2201

Lia

plastic

rover;

.a.1.1"-lo

r,g liber spacers (2): knob.

baller/

clip:

21

" -long piece o) 3, In"

1.,

rod

I one end threaded);

low-

impedance 2n

6nÚ

-ohm

mirrophon

(RC:I

IIK- -99):

jack

mike

wile/

Ioptirnail;

21/2"

x

/,ta" per

hoard: metal

for chassis; mounting hardware.

h

/ride

I -pair

audio cable:

wire:

solder; etc.

+

BI

9V -

T

Fig.

6. An excellent wireless

microphone

can be

made

using

the

KD2114.

Speech

quality

is

very

good (with

the

microphone

suggested),

and

range is

about

50 to 150 feet,

depending on

receiver

used and its

antenna.

30

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