Epson L90P - TM Two-color Thermal Line Printer Instrukcja Użytkownika Pobierz pdf (Strona 44)

JI

MIC

Fig. 1.

A low -cost commercial

transistor amplifier saves a lot of

wiring. Besides its

use

in

noise control, the circuit can

also be

used

as an audio baby

sitter, or as a sound

- powered

burglar alarm.

100K

LEVEL

r

IN

COM

AMP

8f.

GN + - 16f.

S

POR

C0M

R2

2.7K

TO

ALARM

CIRCUIT

NO

--

BI1

-DIO

OFF

(EITHER) RELAY

PARTS LIST

AMP-4-transistor, 3 -watt

amplifier

(L

m

ette

99T9132, Burstein- Appleby 49.9210,

or

simi-

lar)

B1 -6 -volt

battery

for

power

supply)

C1- 50 -µF, 6-volt electrolytic capacitor

D1,

D2-1N34 diode, or similar

I1-

Microphone connector to

suit

microphone

K1-

Low

-current, double

-pole,

double

-throw re-

lay

(see

text)

Q1- Transistor

(GE

-8

or

similar)

Q2 -Lni %unction

transistor 2X2160

ing" period,

the alarm continues,

inter-

mittently,

until

the din subsides. The

alarm

signal does

not feed

back

into

the

circuit.

Construction.

The

physical

layout is

not critical and

almost any arrangement

can be

used. As shown

in

the photo-

graphs,

the

author used a

metal

contain-

er that

happened to

be handy. Perf

-board

construction

is

used

to assemble the

elec-

tronics

while

LEVEL

control

RI,

switch

S1, alarm-

circuit

socket SO/,

and the

microphone

connector J1 are mounted

on

the front panel.

If it is

desired

to

hear

the

audio

output, a

speaker

connector

can also

be

mounted

on

the front panel.

Check

the

circuit of the commercially

made

audio amplifier

module to see

if

the common

output terminal

is connected

to the

battery

positive

lead.

If this con-

nection

exists, it

must be broken so

that

the

secondary of the output

transformer

is isolated

from the

remainder of

the

R1- 100,000 -ohm

potentiometer

R2-

2700

-ohm, ; -watt resistor

R3-47- ohm, / oatt

resistor

R4- 10,000 -ohm,

5_ -watt

resistor

R5- 100,000

-ohm

miniature

potentiometer (see

text)

R6

-390

-ohm, r,/,-watt resistor

Sol- Socket

for

alarm

SCR1-

Silicas controlled rectifier (GE

C106B1)

S1- Two -pole,

three-

position

switch

,llisc. -Perf board, metal enclosure, four

AA

-type

penlight

cells with holders,

crystal microphone,

siren,

knobs, shielded

wire, etc.

amplifier.

The

printed

circuit foil

can be

cut

with a razor

blade

or a very

sharp

knife,

making

sure

that

you

don't cut

any other

leads

or chip or

break

the PC

board.

If you

happen

to

have

an

amplifier

whose

ratings

are

less

than those

speci-

fied in the Parts

List

and

it

has

an out-

put transformer, you

can use it

if

you

connect large -value

capacitors

to

each

side of the transformer primary

and

raise

the value of

R3

to

about

1000

ohms.

In

this way, the audio signal

can reach

the

remainder of

the

circuit

but the

d.c.

will

do

no harm.

Once the perf board circuit

is

built

and

the

front

-panel components

are

mounted, wire the circuit

in

accordance

with

Fig.

1.

With the audio

amplifier

energized

and the alarm circuit off,

cur-

rent drain

is about

15

mA. Although

bat-

teries

were used

in the prototype,

a

6 -volt

d.c. power supply can

be

used.

Use

the

microphone suggested for the

48

POPULAR

ELECTRONICS

1 2 ... 39 40 41 42 43 44 45 46 47 48 49 ... 115 116

Komentarze do niniejszej Instrukcji

Brak uwag