Elenco Electronics MO-1251 Manual do Utilizador descarregar pdf (Página 15)

frequencies as

low

as 0.1

Hz

are

easy to detect.

If you

can

set the

beat that

low

at

10 MHz, that's only

0.01 ppm. Adding the

WWV

toler-

ance gives 0.04

ppm,

but

don't ex-

pect any but the best

Temperature

-Controlled

Crystal

Oscillators (TCXO's)

to remain

steady

at that value. Short- and

long -term

drift,

ambient tem-

perature, and

line- voltage changes

all

play a role in increasing the un-

certainty of

the

calibration,

but

that's a

subject

unto

intself.

If the counter you have, or are

thinking of getting,

has

a

refer-

ence- oscillator

frequency that

won't

beat audibly

with WWV,

then

Radio

-Electronics'

"TV

-De-

rived

Frequency

Standard"

might

be the

next

best thing to packing

the unit off to the manufacturer

for

periodic

recalibration.

DAN

A. NIEMI

Gwinn,

MI

SUMMER SCHOOL

The Massachusetts

Institute

of

Technology's

special Summer

Ses-

sion of professional

seminars in-

cludes several programs

that

should interest

the readers

of

Ra-

dio-

Electronics.

The

following is

a

brief

outline of selected

seminars

that

are being offered:

June 1989

Program

6.01s: "Structure

and

Interpretation

of Computer Pro-

grams";

June

26 -12; Professor

William

M. Siebert.

Program

1.23s:

"Knowledge

-

Based Expert

Systems for

Engi-

neering";

June

26 -30; Prof.

Duv-

vuru Sriram.

July 1989

Program

6.84s: "Parallel

Al-

gorithms

and Architecture

"; July

17

-21; Prof.

F. Thomas Leighton.

Program

6.83s: "Parallel

Com-

puting: Dataflow

Architecture

and

Languages

"; July 24 -28;

Prof. Ar-

vind.

Program

6.87s:

"Robot Manip-

ulators, Computer

Vision

and Ar-

tificial

Intelligence

"; July 24 -28;

Prof.

Berthold

K.P. Horn.

August

1989

One -Day

Seminar: "Writing for

the

Computer

Industry";

August

12; Prof.

Edward Barrett.

Program

6.90s:

Scientific

Super -

computing

with Dataflow";

Au-

gust 14 -18; Prof.

Jack

B. Dennis.

Program

6.64s:

Computer-

Aided Multivariable Control Sys-

tem Design ";

August 21 -25;

Prof.

Michael Athans.

Anyone who

is interested

in

at-

tending these seminars

can

re-

ceive

descriptive

brochures

by

contacting

MIT Summer Session

Office,

Room E19 -356, Cambridge,

MA 02139; telephone 617

-253 -2101.

FREDERICK J.

McGARRY

Director, Summer

-Session Office

of

the Massachusetts

Institute of

Technology

CAPACITOR CONNECTIONS

In

'Antique Radios" (Radio -Elec-

tronics, January 1989) you suggest

connecting capacitors

in series.

Unless

a voltage divider

is imple-

mented, the voltage

will

divide

proportionally to the

DC resis-

tance of

the capacitors.

It is

un-

likely

that

they will

be

the same. If

that distributed voltage exceeds

the breakdown voltage of one of

the capacitors,

it will fail. Then

the

continued on page

93

Get

your

hands

on

the

standard:

POMONA.

Since

1951

POMONA has

grown

to become the

standard of the

industry. And for good

reason.

Our

test products

assure honest test results

because they

are the best you

can

buy.

Specify

POMONA and get

unsurpassed quality,

the broadest product

line, the

greatest selection,

the industry standard.

For your FREE 1989

General

Catalog, circle

reader

service

number

printed below

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ON

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INFORMATION

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