Elenco Electronics MO-1251 Manual de usuario descargar pdf (Pagina 68)

74

D

MACRO WA

VE

OVEN

The big chill: Build a

macrowave

oven.

LAURENCE

HAKEMACHI

ONE OF THIS GENERATION'S MOST SIGNIFI-

cant

electronics

accomplishments,

ranking alongside

the

solid -state

whoopie

cushion and the CD- player-

in-a- boom -box as indicators of our

society's grasp and appreciation

of

technology, is the microwave oven. A

microwave oven liberates you from

much of the tedium of food prepara-

tion and frees

valuable

time

for such

worthwhile

pursuits

as

watching

TV,

staring into space, or partying.

However,

there are

times when

what

you need is not a

way

to heat

things up faster, but a

way

to cool

them down

faster. Maybe

you

have

leftovers to put in

the freezer but don't

want

to

wait

up half the night for them

to get cold

enough

so they won't de-

frost everything else in there. Or

what

if you need more ice cubes right away,

or want

to cool down a case

of

beer

fast? Maybe

you're just

in

a

hurry to

freeze -dry a cat!

What

you need is

what will

be

the

up -and- coming

elec-

tronic glamour -gadget of the '90's-

the

macrowave oven!

How it works

It has long been known, although

never referred to

in polite

company,

that

just as

short- wavelength micro-

waves

can generate heat in many ma-

terials, much longer electromagnetic

wavelengths

known as

macrowaves

can have the opposite effect. Mac -

rowaves remove heat from objects by

causing infrared

radiation

to be

radi-

ated faster

than

it can be generated,

thus producing a cooling effect. Be-

cause of their great penetrating

power,

macrowaves cause immediate

internal

as

well

as surface

heat loss, resulting

in an efficiency much

greater than that

of convection

-type cooling devices

such as refrigerators.

Oven

modification

Until

quite recently, the con-

struction of a

macrowave oven would

have been a difficult

and time -con-

suming affair,

well beyond the abil-

ities

and

budgets of most home

experimenters. However,

the avail-

ability of a device

called a krystron,

which

takes the place

of the magne-

tron found in microwave ovens, has

changed all that.

For

the

sake of

this

project, a ready -to-

install krystron is

available by mail.

(The

etymology

of the word

"krystron," incidentally, is uncer-

FIG.

1-

MACROWAVE OVEN

replaces

standard

magnetron

with krystron.

Type

18 -OZ device

is

shown

here.

FIG. 2- THERE'S

NO

SUCH

TH'NG

as too

much power

when it

comes

to generating

macrowaves.

tain. Some claim that it is derived

from the

Greek

kryo, meaning

"cold." Others

believe it comes from

the Japanese

word

for a microwave -

generating device.)

It is not necessary to start

from

scratch.

An ordinary microwave oven

of the kind you may already own

will

do. The modifications

required are

threefold. First, the existing magne-

tron must be replaced

with

a

krystron

(Fig 1). Depending on the size of your

unit, you will need a krystron desig-

nated 8-OZ, 18-OZ or 24-OZ. A 500 -

watt

oven

will

be converted nicely

with an 8 -OZ

unit; a

1000 -watt or

greater one will work best

with

a 24-

OZ krystron. All that

is necessary is

to remove the existing

magnetron

(which

you have probably

already

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