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BROEL &

KJJCR

Ncerum

- Denmark Technical Description

2307.1

The

Level

Recorde

Type

2307 consists mainly

lifier , an

Electro-dynamic

Writing

System

, a Paper Drive System

and

a Power

Supp

RECORDING

AMPLIFIER

Input

Amplifier

The

input

the

Level

Recorder

unsymmetr

al.

The

gnal is first fed

through

the

continuously

variable INPUT

POTENTIOMETER

and t hen

the

calibrated INPUT

ATTENUATOR.

Due

stray capacitance

the

INPUT

POTENTIOMETER

the

frequency

response

the

highest fr

equen

will be

affected

the

INPUT

POTENTIOMETER

not

set

t i

" 10".

The

calibrated

INPUT

ATTENUATOR

enables

the

input

signal

accurately

attenuated

six 10 dB

steps

within

±0.2

dB.

From

the

INPUT

ATTENUATOR

the

signal is fed

the

Range

Potentiome

ter.

I n

the

Range

Potentiometer

there

are

precision resi

stors

onnec

the

216

silver lamellae

that

make

contact

with

the

slider which

atta

ched

the

pen drive.

The

Range

Potentiometer

sets

the

dynami

c ran

and r

espon

the

Level

Recorder

The

pick

off

voltage

from

the

slider

fed

electron

chopper

operating

1 kHz.

The

chopper

consists

two

Field Effect

Transistors

(F ET's) whi

are

switched

"on

and

off

" 1000

times

every second.

They

are

switched

antiphase

and

when

they

are

tched

one

passes

the

signal

the

input

amplifier

and

the

other

shortc

ircu

the

input

the

amplifier

ground

during

the

remaining

time

the

switching

cyc

le.

Their

chopping

function

selected

only

when

the

Level Recor

der

is swi

tched

record

levels.

the

other

three

positions

the

RECTIFIER

RESPONSE

selector

a f

-20

applied

the

base

V 3 via R

locking

the

mult

vibrator

the

state

where

the

signal

allowed

proceed

the

input

amplifier.

The

balanced

input

amplifier

coupled

and

provided

with

both

AC and

feed-

back.

The

gain

approx

dB.

b. Rectifier

The

output

from

the

input

amplifier

applied

a bridge

type

full wave

rectifier.

The

RECTIFIER

RESPONSE

networks

are

symmetr

ically disposed

with

respect

ground

which

ensures

that

the

resolving

power

the

pen

drive

system

maintained

for

both

rising

and

falling signals.

The

specially designed rectifier

circuit

can

be switched

measure ei

ther

the

true

RMS,

the

arithmet

ic average

half

the

peak

value

the

nput

signal.

RMS

detection

makes use

the

highly

accurate

principle

a biased d i

ode

and

transistor

which

performs

within

± 0.5 dB,

this case

a crest

factor

10.

Following

the

rectifier

circuit

the

LOWER LIMITING

FREQUENCY

response

circuit

which

has

initial

effect

the

averaging

the

measured

signal.

This

circuit

determines

the

lowest

frequency

which

the

Level

Recorder

respond linearly. It

can

set

either

"2",

"10", "20",

"50"

200

the

selector

. LOWER LIMITING

FREQUENCY

each

these

roll·off

frequencies

the

response

the

Level

Recorder

drops

0.3 dB.

Output

Amplifier

The

driving

system

protected

from

being over driven

the

first limiter

18,

and

20).

The

threshold

the

limiter

designed so

that

the

drive

system

reaches full driving

power

when

the

signal

fluctuat

reaches i

mit

The

output

signal

from

the

first limiter (DC)

compared

with

a built·in

balanced

reference

voltage

produce

difference

signal

which

used

drive

the

output

amplifier via a

second

limiter.

This

difference

signal

attenuated

steps

attenuator

marked

POTENTIOMETER

RANGE.

The

attenuator

setting

determines

the

resolving

power

the

Recorder

which

the

ability

faithfully

follow detail

fluctuations

the

signal level.

From

the

POTENTIOMETER

RANGE

attenuator

the

signal

fed

the

second

limitet.

The

reason

for

the

second

limiter

ensure

that

the

drive

signal

the

output

amplifier

section

independent

the

magnitude

the

servo

error

signal

once

it has

reached

certain

value.

This means

that

the

signal

the

output

ampl

ifier

section

will remain equal

less

than,

a fixed value.

The

output

amplifier consists

integrated

circuit

DC amplifier

and

push

·pull

power

amplifier

. This

latter

stage

operates

as a

type

single

ended

push-pull amplifier.

From

a special

winding

the

moving coil

the

electromagnetic

drive

system

a velocity

dependent

signal

induced

The

signal

introduced

negative feed

back

the

input

the

output

amplifier

section

The

feed

back

signal will

completely

control

the

output

signal

from

this

section

as long as

the

signal

from

the

second

amplitude

limiter has reached its

constant

value,

which

the

case

when

the

limiter

act

The

speed

the

writing

system,

and

hence

its averaging

effect

the

recorded

levels,

can

adjusted

according

the

figures

around

the

IT-

ING SPEED

control

knob

Lower

Limiting

Frequency

Writing

Speed

10Hz

20Hz

200

-56V

o------------------~~

mm/sec

100

160

250

"Decrease WS

Increase

LLF

+56V

The

stability

the

complete

system

determined

the

combined

settings

WRITING SPEED, LOWER LIMITING

FREQUENCY

and

POTENTI-

OMETER

RANGE.

the

correct

setting

POTENTIOMETER

RANGE

selected

for

the

Range

Potentiometer

in use,

overshoot

and

instability

the

system

could

caused

selecting

too

higha

WRITING SPEED

relation

the

setting

LOWER

LIMITING

FREQUENCY.

A lamp

marked

"Decrease

Increase

LLF"

will light

the

limit

for

stable

operation

exceeded.

Removal

the

Range

Potentiometer

When

the

Range

Potentiometer

removed

great

care

must

taken

not

damage

the

slider. By having

the

writing

system

all

the

way

the

right

damaging

the

slider

minimized.

Power

"ON"

When

the

screw,

which

the

Range

Potentiometer

mounted

the

unit,

loosened a

microswitch

disconnect

the

moving coil

from

the

output

amplifier

and

connect

the

coil

the

fixed

+ 24 V

supply

via a resistor (R 152).

The

writing

s,ystem will

then

to,

the

right

and

the

current

limited

1/10

the

current

normally

supplied

the

ampl

ifier.

The

function

independent

the

position

the

Standby/Operation

selector.

9.72 2307

from

serial

377302

1-1

Brand	BRUEL & KJAER
Model	2307
Category	Measuring Instruments
Language	English

BRUEL & KJAER 2307 User Manual

Table of Contents

Questions and Answers:

BRUEL & KJAER 2307 Specifications

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