Epson L90P - TM Two-color Thermal Line Printer Manual de usuario descargar pdf (Pagina 41)

wave

with

frequency

1/10

that

of the

input.

It should

about 1.8 volts

amplitude

and have

a 6:4

duty cycle.

This,

of course, is

also

the

input

to the

scaler.

COUNTER SPECIFICATIONS

Function:

Measuring

frequency,

events, events -

per- unit -time,

the

ratio

of two

frequen-

cies. It is

also a source

precision

0.1

1 -, and

10- second timing signals.

Ranges:

0 -200 Hz,

0-2 kHz, 0-20

kHz, 0-200

kHz, 0 -2 MHz,

events, and externally gated

events or ratio.

Accuracy: Power

-line stability

plus

minus

one -half

count.

Typical

accuracy

0.1 %.

Resolution: One part in

2000

full scale.

0.1

on 0- 200

-Hz scale.

Sensitivity:

Switch

adjustable from nominal

0.1, 1,

10 volts. For

sine waves -30 mV

r.m.s.

from 50 Hz

3 MHz;

300

mV r.m.s.

from 5

to 50 Hz.

For

pulses- symmetric

pulse, 100 mV p -p; narrow

positive pulse,

50 mV p -p; narrow negative

pulse, 700 mV

p-p.

Input

conditioning: Automatically provided

for

all but mechanical contacts. High -gain IC

comparator provides

snap

action,

-mV

noise

offset, and

-mV hysteresis. Any

reasonable wave shape is acceptable, in-

cluding sine

square waves,

rectangu-

lar pulses

of either

polarity.

Input

protection: D.c. blocking to 200 volts.

Combination dual

-diode limiter

and d.c.

restorer

allows

safe

measurement

in prac-

tically all test

situations.

Input impedance: 10 -volt range, 112,000

ohms; 1 -volt

range,

12,500 ohms; 0.1 -volt

range, 2500

ohms.

Typical shunting ca-

pacity is less than

pF.

Gating: Fully synchronized master gate used

to eliminate the one -count ambiguity

as-

sociated with older

counter

designs. Last

digit

is constant rather

than bobbling be-

tween

two values.

Display:

Switch selects

hold

follow.

Infinite

display in hold function, automatic

updat-

ing in follow. For

0-200 Hz, 10- second

measure, 10-

second display; for 0-2

kHz,

1- second measure,

1- second display; for

higher frequencies,

0.1- second measure,

0.9-

second display.

Miscellaneous: Automatic

overrange indicator

comes

on when full -scale count

is exceed-

ed. Floating decimal points.

Manual reset

and override. Time gate

outputs

available

at gate

terminal

during measurement.

Modular construction

adaptable

to crystal

time base for higher

accuracy. Extendable

with input

scaling to 0 -20 MHz

or 0 -200

MHz. All solid -state

circuit

uses 26 IC's,

43 transistors,

and 14 diodes.

The frequency

output B /10

should

be 1/10

that

A /10

and 1/100

that

the input

to the A

scaler.

Its

amplitude

depends

the

setting

the range

se-

lector

switch,

but it should

range

be-

tween

1.8

and 3.6 volts,

positive.

should

have

6:4

duty cycle

and rise

and fall

times

of about

ns.

The

GATE

terminal

the D

scaler

should

have

repeating

waveform

that

goes

positive

about 2 volts

for

0.1 second

and to ground

for

0.9 second.

The

output

at C/2 should

repeat-

ing signal

that is

positive

for

second

and ground

for 1

second,

with

an ampli-

tude of

about 2 volts.

The

output

C /10 should

re-

peating

symmetrical

square

wave

with

frequency

0.2

Hz (5-

second period),

with an

amplitude of

about

2 volts, posi-

tive.

Gate (M6)

There

should

a clean

-Hz

sine

wave

at the junction

and

on this module

( terminal

60 Hz)

It should

offset

with the negative

peak

at -0.7 volts

and the

positive

+ 2.4 volts.

7 of

ICI

there

should

a 60-

Hz rectangular

wave having

50 -ns

rise

and fall

times and

an amplitude

about

volts. The output

8 of IC2

should be

20 -Hz rectangular

wave

with

1:2

duty cycle

and

2 -volt

positive

amplitude.

The

0.1 SEC output of

this

module

should be a symmetrical, positive

-going

wave at

0.1

second,

with 50

-ns rise

and

fall

times. The

SEC output

should

positive for 10

seconds

and

ground

for

10 seconds.

Reset. The reset

buss

(RST

all

modules

except M2) is

at ground

most

the time. Depressing

the

front

panel

RESET

switch should raise

the

level

the buss to about 1.6 volts

and

all

DCU's

should

promptly

return

to a zero

indica-

tion. Also

during normal

operation,

there

is,

on the reset

buss, a brief pulse,

about

2 microseconds long

and 1.6 volts

amplitude, immediately

after the leading

positive

edge of the selected

time

gate.

This waveform erases

the old

counter

indications

and drops

them to zero

the

instant

new

measurement

is to

begin.

This

waveform

can be seen best

lab

-type oscilloscope

having

both trig-

gered sweep

and

vertical

channel

delay.

April, 1969

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