Tektronix 221 MANUAL

Instrumentation

IV

Have

instrument,

Be the readout analog, digital, CRT, or hard copy,

"portable" and "performance" are now

Once upon a
of curiosity, courage, and the judicious application of
two moistened fingertips.
men, and others who
opposed to the controlled environment of a well­stocked
manageable, and accurate
need, the integrated circuit, coupled with digital
readouts and improved
welcome revolution. Oscilloscopes, function genera­tors, strip chart recorders, spectrum analyzers, as well
as vastly improved volt-ohm mijliammeters, are now

ready to
doesn't stop with these familiar items. New types of
instruments such as a portable digital thermometer,
which measures surface temperatures
cal contact, have helped
analysis into routine field checks. In fact,
perspective on
gained from a good look
and recently announced portable instruments.

New

face for an old friend

Perhaps the piece of portable instrumentation most
familiar to any engineer
(VOM). Consisting of a high-impact molded case en­closing simple
inexpensive batteries, and a large multiscale meter,
the general-purpose VOM
ized by

years,

the

probes, has

external appearance rivaled only.by Volkswagen.

But

over

the

much portable

tinues to sell more
price of $74.50),

digital readouts has been recognized. Providing a

choice of ac line or NiCad
son's model

play

plus

and null measurements.

Customers preferring a lab-style metal case and
extra-large digital readout are offered Simpson's
model

460
blanking of nonsignificant zeros and extended
life-up

Meanwhile, many other new, interesting, and com­petitive multimeters are being offered to
neering community in both digital

eties. Dana Laboratories, Inc., Irvine, Calif., for ex-

D®ssociate

time,·

remote troubleshooting consisted

But

field engineers, service-

must

work

"on

location"-as

lab--have

go

wherever the problems are. And variety

the

Simpson Electric Co.'s model

260,

maintained

constantly demanded rugged,

test

equipment.

battery

current

progress and future trends

is

but

dependable electronics, a couple of

packs, has brought a

turn

difficult and costly

at

some currently successful

the

volt-ohm milliammeter

is

probably best character-

without

260.

To

the

this

physi-

best

For

with its complement of test leads and

a popularity and continuity

37

-of

the introduction of low-cost digital displays

past

several years has changed

test

equipment. While Simpson con-

260s

than

ever

the

interpretive-free convenience of

battery

360

VOM

(at

$295) features

the

face of

(at

the

current

operation, Simp-

an

LED dis-

a small analog indicator for scanning peak

an

VOM

(at

$395), which includes

automatic

battery

to nine hours on a full charge.

the

engi-

and

analog vari-

Editor

will

in

ample, has introduced their•

tra~sa

.

the same package

~

Danameter
crystal digits as a direct challenge to established ana­log VOMs. Some key features include
larity,

for

de voltage measurements, a tough case

automatic

molded cycolac, and one year's normal use on a single
9-volt

battery.

On the market

The

price:

about

$195

complete.

a year now

is
hand-held digital probe from Hewlett-Packard, Palo
Alto, Calif. Battery-powered, pocket-sized, and com­pletely self-contained, the 970A's controls consist of
two

thumb-actuated

lever for measuring ac volts, de volts,

slidebars

and

a push-to-test

and
cuit connections are made through a ground clip and
a movable-removable probe tip. A
na plug with a clip lead can
et

for measurements requiring two clip leads. A single

mount

MOS integrated circuit handles all the

standard

in

the

auto

and polarity adjustments, settling to yield a proper

is

reading in less
gram 970A sells for

than

two seconds (typical).

$310

and will make over

measurements on a full charge of its Ni Cad battery.

Predating the

model

167

Full-scale

voltage range

•

de

capability

•

ac

capability

Full-scale

current range

•

de

capability

•

ac

capability

Full-scale

resistance range

Range

mode /

Price (single unit)

HP

970A by

auto-probe digital

lO0mV

100 V

..

l0µA

l00µA

1

10

100

10 A

lO0Q

1

10

lO0kQ

1

10

lO0MQ

digits

at

multimeter

1 V

10 V

1

kV

mA
mli
mA

1 A

kQ
kQ

MQ
MQ

least a year

Ballantine

3/24

I

A

u

manual/3 manual/3½

$195

Optional 10-A

shunt available.

·.,

with liquid

po-

the

970A, a

ohms. Cir-

bana-

probe sock-

ranging

The

200-

2000

is

the

from Keith-

Danameter

·---------·-··-

-·-

-.--

$195

;r-.

Dana

·-·--

--·--

----

-----

--

··--

-·---

-

··-••'-••·

·-···-

..

-------

----------

-----

-

-·.

IEEE

spectrum

NOVEMBER

__

.-!f

__

--

1974

_·

-

.__J

.

..,

ley Instruments Inc., Cleveland, Ohio. Physically
unique among portable multimeters, the

167
a probe-mounted display linked to the function selec­tor and probe cradle via a special cable. Auto rang­ing and autopolarity, plus push-to-test operation, con­serve

the

batteries while speeding multipoint mea-

surements. And the

167

converts

to

a typical
configuration simply by inserting the probe into the
cradle and then connecting standard
front-panel

banana

jacks (the probe's LED numerics

test

leads to the

continue to serve as the readout). Probe, case/cradle,
and alkaline battery set come complete

While

HP

and Keithley have settled on LEDs as

the

standard

readout for portable gear,

for

$375.

Data
sion, Wakefield, Mass., offers a high-intensity plasma
display on model
timeter.

The

245,

a

$295

miniature digital mul-

rechargeable batteries last about six
hours and a high-impact case protects the instrument
from everything
switching

is

but

manual,

ov_erzealous
but

LSI and CMOS circuitry

borrowing. Range

handle autopolarity and automatic zeroing.

Apparently successful with the

duction two years ago,

Data

245

since its intro-

Precision has now gone
after the lab instrument market with the basic per­formance features of
use. Introduced in August

1

4

h-digit ac-powered multimeter that, like the

the

245

packaged for benchtop

at

$325,

model

derives its accuracy from a carefully maintained +1­volt zener reference.

features

"bench"

Preci-

1450

is
245,

Contoured like a calculator and operating off
chargeable NiCad batteries,
21

offers ac and de volts, resistance, and capacitance

Data

Technology's model

measuring capability combined in a hand-held mul­timeter. Users have the choice of continuous opera-

. tion or extending battery life with a push-to-read but-

ton

..

For an extra

$10,

a push-to-read probe allows
hands-free testing while conserving battery power.
impact-resistant polycarbonate case, handy carrying
pouch

that

clips on your belt, and 0.68-cm LED read-

outs help

the

$269

model

21

perform under rough

field conditions.

But

as the popularity of Simpson's

260
analog multimeters have not fallen categorically to
the digital onslaught. Weston Instruments, Inc., New­ark, N.J.,
670,
on printed circuit boards

for

an analog

example, has recently introduced model

VOM

which can measure direct current

without

breaking connec­tions. This ac powered "in-circuit" tester uses two spe­cial dual-tip probes
results are obtained by probing the longest

for

measuring direct current. Best

or

continuous conductor available. One contact
probe senses the voltage drop on the current-carrying
conductor under

te;t.

A

differential amplifier senses

this condition and generates a bucking current until

a

it balances the voltage drop. This bucking current
proportional to the circuit current and

is

read on the

meter. Housed in a shock-resistant polycarbonate
thermoplastic case, the

670

lists

for

$249-including

re-

An

will testify,

narrowest

in

each

is

Even a modest budget
battery-powered digital multimeters currently available.
Remember, most

haps the hardest

as

a percentage

Zero stability, temperature coefficients,

Data

Precision

245

Data Technology

21

of

around $300 allows wide selection from among the many compact,

of

the manufacturers listed produce a wide variety

parameter

of

reading

to compare among competing

±

one least significant digit,

Make and Model number

Fluke

8000A

[I

II

..

-

Still

and

frequency sensitivity can

Heath

SM-4440

Hewlett-Packard

!

Single range

200µ.A

full scale

(ac and

de)

: :

!

: :

don't see the performance

DMMs

or

±

970A

*

of

digital instruments. Per-

is accuracy. Usually

a

percentage

be

~'

of

cited separately.

Keithley Simpson Weston

168 360 4442

!

•

you

need?

ii

full-scale range.

is given

I I

-

-

,anual/4

$

295

'F

1

/2

manual/31/2

$ 269

(also measures

capacitance) shunt available.

Mennie--Have

inslrurnent,

manual/3½

$ 299

will travt:I

manual/31/,

$ 250

(assembled) •Optional

auto/3

$ 310

:-

~,_:,,

~

,.,

)"J.,._~~:

~·;

.

.

1

/2

auto/3

$ 299

1

/,

manual/3

$ 295

1

/2

manual/3

$295

1

/2

fi9

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