Elenco Electronics MO-1251 Manual do Utilizador descarregar pdf (Página 46)

100

mitter, the IR receiver

/RF

transmitter,

and the RF receiver /alert beeper, re-

spectively. All resistors are

installed

vertically.

Capacitors

mount flush

against the board

with

minimum lead

lengths -that is

especially

important

in the RF and tone -decoder circuits.

Install XTALI

after C9 and C10 are

installed. All transistor leads

are ap-

proximately

1/4-inch long. If you de-

cide to

control

the

IR receiver /RF

transmitter manually, rather than use

the automatic daytime -off circuit,

omit Q6's circuit and install an SPST

switch between

the

solder

pads that

were intended for Q6's source

and

drain.

Test points

For the RF receiver

/alert

beeper,

make TP1 (test point 1) by placing a

ferrite

bead

over one

end

of RIO, and

then solder the resistor onto the PC

board so that it stands

vertically,

with

the

ferrite

bead and the ring on top.

Also, be sure that there is an easily

accessible ground test point.

TP2 is

located at the junction of R17 and

C14.

The IR receiver /RF

transmitter

board

has three test points. TP1 is

located on the free

end

of CI 1. Just

temporarily solder a piece of red

wire

to the TP1 pad, and a piece of black

wire to ground (both should be about

4 inches long). In

the alignment

pro-

cedure

that follows,

those two

wires

temporarily attach to an external au-

dio amplifier /speaker. TP2 is the

point

where

R16 and IC3

pin 3

meet,

and TP3 is between R7 and the cath-

ode of DI.

If you find that the test points are

picking

up interference, you may have

install

a ferrite bead over the test

point

was

previously described.

,...<.,..

2111

V.,

..,

FIG.

9-THE PROTOTYPE

SYSTEM. The

unit

the

left is the IR

transmitter,

the

one

the

center is the IR

receiver RF

transmitter,

and the

one on the right is

the

RF receiver

alert beeper.

SOURCES

All of the parts or

parts kits

men-

tioned in the Parts List are avail-

able

from Time

Space Scientific,

101 Highland Dr., Chapel Hill, NC

27514. Be

sure

to add $4.50 to any

total order

for

shipping and

han-

dling.

For technical

information,

write to Time Space Scientific, and

please include a

self-

addressed

stamped envelope.

The

completed system units are

shown in Fig.

Optics

Mount the optical components in

their respective enclosures as follows:

For

the IR

Transmitter,

drill two

1/4-

holes in the cover of the case

with

their centers 1/2-inch apart. Install IR-

LEDI and

IR -LED2 in

the holes using

LED mounting rings. If necessary,

connect a pair

of wire leads

between

the PC board and the IR- LED's, but

keep

the leads reasonably short.

Install

phototransistor Ql into the

enclosure of the IR receiver /RF trans-

mitter, the same way

you

installed

the

IR- LED's. Also, mount LDRI adja-

cent to Ql so that both are

exposed

the

same intensity

of ambient

light.

Mount

LDR2 in a location that

will

ensure maximum exposure to ambient

light.

Alignment

For test purposes,

each of the three

circuits

can

powered

from

a 9 -volt

battery,

but for continuous operation,

rechargeable batteries or AC adapters

are recommended. The IR

transmit-

ter,

and the RF receiver /alert

beeper

work well

from a 6 -volt gel -cell bat-

tery,

but

12 -volt

DC supply is re-

quired

for the IR receiver /RF

transmitter. And, if the connecting

wires

to the 12 -volt supply are longer

than two feet, install a 50 -RH RF

choke in series

with

the negative sup-

ply

lead at the PC board.

The

alignment requires a frequency

counter that is

capable

of measuring

audio

frequencies, and an audio am-

plifier /speaker

that has either an aux-

iliary-

or a microphone -input

jack (a

portable

cassette player

with

a micro-

phone

-input jack can

be used). All

test points are referenced to

the

circuit

ground.

Cover

LDR2

with

black tape

plastic to shield it from ambient

light.

Attach

a power

supply to the IR re-

ceiver

/RF

transmitter

circuit and al-

low one minute

for

C17 to

charge.

Then, using a small screwdriver, turn

's core counterclockwise until

protrudes

approximately 1/32

inch. At-

tach

a frequency counter to

TP2

and

adjust R11 for a reading of

490

Hz.

Disconnect the frequency counter

and, using

the appropriate con-

nectors, attach the audio amplifier/

speaker (the portable cassette record-

er) to TP1: A

490

-Hz tone

should

heard.

Apply power to the

IR transmitter.

and CDS1

BLACK

TUBING

RECEIVER

OR TRANSMITTER

Fo- 7 INCH -+{

0.5

INCH

FIG. 10-A LIGHT SHIELD

may be needed

depending

on the ambient

light levels

(see

text).

While

listening to the audio signal at

TP1, place the IR transmitter in front

of phototransistor

QI; a higher -

pitched tone of approximately 1500

Hz should also be heard. After a few

seconds, the 490 -Hz tone should stop,

leaving only

the

1500 -Hz

tone.

Mo-

mentarily

interrupt the

beam; the

490 -Hz

tone should again be heard.

Expose

LDR2 to light.

After a few

seconds the audio tone(s)

should stop,

indicating that Q6

has shut off the

circuit. Cover

LDR2 so that the

receiver

/RF transmitter

operates.

Turn off the IR transmitter.

Apply power to the RF receiver/

beeper (BZI may

sound

momen-

tarily).

Connect a frequency counter

to TP2, and adjust R18 so that the

counter measures 490 Hz. Next, con-

nect the audio

amplifier

/speaker

TP1. Adjust

Tl's core until the top of

the

core

level

with

the top of the

transformer. A rushing noise

-and

possibly the 490 -Hz audio tone from

the RF transmitter -should be heard.

Adjust both TI and Ll (in the receiver

and the transmitter)

for

the

loudest

490

-Hz tone. Momentarily turn off

the

receiver

/beeper and remove

IC2. Collapse the antenna on the RF

transmitter and place it about

30 feet

from the receiver. Then, turn on the

receiver and fine -tune

Tl (on

the

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