Epson L90P - TM Two-color Thermal Line Printer Manual de usuario descargar pdf (Pagina 53)

LINE

D3

105059

R3 R6

27K

IK

--L

Ci1

.225F

SCRI

CG

DI

6el

10 5059

R2 05 105059

117

2.7K

.7K

D5

VAC

G C

2N4990

C

'

UP TO

SCR2

-

200W

LOAD

CI

RI

IK

R4

27K

CI06BI

A

D4

105059

A

.22yF

LOAD

Fig. 1. The

heart

of this circuit is

a

relatively new

semi-

conductor,

the silicon unilateral

switch

(D5).

Controlled by

the transistor

circuits,

the SUS in

turn

controls

the SCR's.

PARTS LIST

('1,

C2, C4

-U.2 2 -µF,

low-

voltage

capacitor

('3,

C5, C6-

0.05

-µF,

low-

voltage capacitor

D1

-D4- 1X5059 diode

D5- Silicon unilateral switch (GE 2N4990)

R1,126-1000-ohm,

' -j -watt resistor

R2, R5 -2700 -ohm,

¡ -watt resistor

R3,

R4-

27,000

-ohm,

!'_¡-watt resistor

merciai

potting

compound.

An

alternate

is

to give

the complete

board several

coats of nail polish, preferably transpar-

ent,

allowing each coat to dry thoroughly

before applying

the

next. To

avoid shock,

take care not

to damage this

insulation

when handling

the board.

Operation.

Connect

a

lamp

of 200

watts

or

less

to the load terminal

of the board,

then

connect

the

other

side of the lamp

and

the line

terminal of the board

to a

Fig.

2. Actual -size PC board is very

small so

use

care when making

it.

Unlike conventional boards,

this

board

uses area

contact

rather than

a pattern.

TOUCH

ON

TOUCH

OFF

C3

.050F

G

C4

.22yF

C5

05

yF

R7

IM

OFF

TOUCH

CONTACTS

ON

i

C6

.05yF

Re

IM

R7,

R8- 1-

unegohnn

resistor

SCR1,

SCR2- Silicon

controlled

rectifier (GE

C106 -B1)

O1- 2X3394

transistor

O2- 2X2925

transistor

Alisc. Onn- nnegoluna resistor (

optional, see text),

line

cord, metal for

touch

contacts, insulated

wire_

source

of

commercial 117

-volt

a.c.

power.

Placing

a

finger

tip on the "touch on"

area should

make

the

lamp

go on; con-

tacting the

"touch off"

area

should make

it

go out. A pair

of small metal plates

can be connected

to

these

terminals,

us-

ing insulated

wire as

the connectors, to

act as the actual

touch plates. If

the

lamp should only flicker

when

the "touch

on"

terminal

is contacted,

reverse

the

power -line plug.

If you

want

to extend the touch plates

for

some

distance, connect a one -megohm

resistor to

the line

terminal and locate

the other end of

the

resistor (by

way of

an insulated connecting lead)

between

the

two touch

plates.

Simultaneously

touching both

the

end

of the one -megohm

resistor and either of the

touch plates

Fig.

3. The components

will

be

tightly

packed

(see

photo

at

right), so mounting is rather unorthodox.

Note

that transistors and D5

are "upside down."

LINE

' LOAD

April, 1969

57

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