Mitsubishi Electric MUX-25TV - E1 User Manual download pdf (Page 38)

R19

50K

GAIN

47uF

NOTE:

NE5534N

100 K

4.7K

-15V

601

Output

601

Output

Fig.

2. This alternate

output circuit

provides outputs

that properly

match

600 -ohm

unbalanced

inputs.

l io. 3

This

is the schematic

diagram

of the power

supply

used

with the

Step

Generator's

circuitry.

The output

from this

oscillator

fed

into the clock

input

of counter

IC2. The counter

advances

each

time

the clock

pulse goes

from ground

positive.

As the counter

advances,

each

the

outputs

is made posi-

tive,

one at a

time,

in step

fashion.

The

reset pin

is normally

at ground

by setting

SI to the

STEP

position.

Throwing

to the

SET

LEVEL posi-

tion

resets

the counter

to 0 and

"sets"

the

function

generator

to its

fixed

frequency position.

Thus, go-

ing

from

SET LEVEL to

STEP always

starts

at the same

spot.

The outputs of

counter

IC2

drive

the control

terminals

of analog

switches

/C3, /C4 and

105,

which in

turn switch

various

values for

Rx.

When

control

pin is

made high,

the

switch

is on.

(The analog

switches

have an

on resistance

of approxi-

mately 100 ohms.)

Output

buffer

amplifier

IC7

con-

tains a pair

high

-performance

op-

erational

amplifiers

that

provide

bal-

MODERN

ELECTRONICS

/ April 1986

anced 600

-ohm outputs.

Inverting

amplifier

IC7A's input and output

are

180 degrees out

-of- phase,

while

buffer

IC7B's

input and output

are

in -phase

with

each

other.

Using one

output

from

IC7A and one

from

IC7B yields a balanced

output. Out-

put impedance

is fixed at 600

ohms

R24 and

R26 for OUTPUT

and by

R25

and

R27

for

OUTPUT 2.

With

two

outputs available,

you can

check

both channels

of a stereo amplifier

si-

multaneously.

In Fig.

2 is

shown a

scheme to de-

rive two unbalanced outputs.

Only

one amplifier

is needed

in this case.

Output

impedance is determined

the

values of the

resistors in series

with

the output.

These

values

can

changed

needed.

shown

in Fig. 3, the power

sup-

ply for the project

is relatively sim-

ple. Its 30 -volt

center

-tapped trans-

former feeds

four -diode bridge

whose output

filtered

by two capa-

citors and

is regulated

+ 15 and

volts with

separate

IC regula-

tors. (A

24 -volt center

-tapped trans-

former and

12 -volt

regulators could

used, but

maximum output

from

the project

would be

less.)

Construction

There is nothing

critical about

con-

struction.

Just

be sure

keep the ac

line and power

supply

proper as far

as possible

from the analog

circuits.

Any

reasonable

method of

wiring the

project can be

used -a

printed

-cir-

cuit board

your own design,

per-

forated board

and solder

Wire

Wrap

hardware or even

large sol

derless

breadboarding

socket.

It is a good

idea

socket

all

ICs ex-

cept the

regulators.

As you

wire

the

project,

referring to

Figs. 1 and 3,

sure

to observe

proper

orientations

for the

ICs and polarization

of elec-

trolytic capacitors

and diodes.

Fig. 4 shows the

Step Generator's

analog

cirlcuitry

wired

on a

x 4"

perforated

board

with the aid of

ap-

propriate

mounting

/soldering

hard-

ware. The power supply

section

(Fig.

was

assembled

on a separate

2 " perforated

board.

Because

current

drain

is quite

low,

no heat sinks

are

required for the

regulators.

The project

fits

nicely into an 8"

x 41/2 " chassis box.

This size

box

assures

ample

front panel

area

for the

controls,

switches and

LED, as

well

enough

interior space

to insure

iso-

lation of the power

supply

from the

main analog board.

Machine

the chassis

box as

re-

quired.

Drill holes for

the

controls,

switches,

output connectors

and

LED

on the

front panel, and

the pow-

er supply

board,

power switch,

pow-

er transformer,

fuse holder and

line

cord

on the

rear panel.

The analog

board

mounts on

the floor

of the

box, as

far

forward as possible

with-

out

interfering

with the

front -panel

components.

Mount

the power

supply board

with 6 -32

machine

hardware and

spacers.

Mount

the power

trans-

Say You

Saw

It In Modern

Electronics

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 83 84

Comments to this Manuals

No comments

Mitsubishi Electric MUX-25TV - E1 User Manual Page 38

Comments to this Manuals

Related products and manuals for Split-system air conditioners Mitsubishi Electric MUX-25TV - E1