Páginas DesdeRadio Electronics January 1991

8/18/2019 Páginas DesdeRadio Electronics January 1991

1/4

UILD A

NEGA

TIVE ION GENER TOR

I F

Y O U V E S EE N D VE RT IS E

-

me n ts fo r n eg

a tiv

e ion

gene

ra

to

rs

in mail- o rde r

ca

ta

l

og s

and wondered how

t

hey work.

t

hi s

project is for

you. The simple vers ion de

sc

ri

bed h

er

e p ro

vi d

es in

si gh t

in to th e ir theory and

app licatio

ns ,

an d is bo

th

in

formative and en te rt a in ing .

Som e of

th

e d

e m o n

s t r a

tions you ca n do w i th

.i

t will

a m a z e y o u a n d your

friends .

Many cla im s

ha v

e been

mad e for th e benefioial at

t r i b u tes

o f

n eg a t ive at

mospher ic io

ns

on human

and

plan

t life , es

pecia

llyby a

Dr. Albe rt Kru eger of the

Un ivers ity of Ca lifo r

nia

.

Stu d ies h ave s hown that

negative

io n

s promote

ph

ys

ical

a n d

men ta l alertness

a n d w

e ll-b

e i n g ,

w h i l e

positive at mosp h er ic ions

(su

ch

as in

pollu

ted a ir )

ca u se d

isc

om f o

r t

a n d

la

ssi

tu de.

Certa in negative

io n

prop

erti es can be demons trated.

F

or

example, the su r round-

ing air after a thunde rsto rm

smells cle

an

an d fre

sh

.

du

e

to gen erat io n of n egative

i

ons

fr

om

lig h t n i ng. The

negative ions t tac h to

sm oke . du

st.

a n d p

ol l

en

p

articl

es,

brin

ging the m to

t

he

g r ound to di s

ch

a rge ,

leavt n g fr esh , c le an a ir.

Tha t s w hy a cool ro

om

with

a b reeze is invi gora ting .

comp a re d wi

th on

e that s

st i

flingly h eated . Cool a ir is

gen e ra lly n eg atively i

oni

zed ,

wh

erea

s h ea ted a ir is ge ne

ra

lly

po s

itively i

on i

z

ed

.

Negative ions a re a ir

mo l

ecu les

with

on

e or more excess elec

trons ,

produ

ced in th is

case

by a

low-power. 9 to 14-

ki l

ovol t DC

supp ly

Th

e po

si

tive terminal is

gr o

u n

ded, a nd the othe r th e

em

itte

r ) is a n eedle ex

pose

d to a ir.

To generate positive ion s . the po

l

ariti

es w

ould

be reversed.) Extra

electro

ns on

t

he

em i

tt e

r s surface

produce a hi

gh

local elec tric fi

el d

owing to its pointed s

ha

pe . Th e

electrons ex it th e em itter needle s

uild this negative

ion generator and

u

some

charge

in your life

ANTHONY J CARISTI

WARNING Thisarticle deals with and

involves subject matter and the use of

materials and substances that may be

hazardous to health and life. Do not at-

temptto implement or use the information

contained herein, unless you are experi-

enced and skilled with respect to such

sub

ject matter,

materi a

ls , and sub -

stances. Neither the publisher northe au-

thor make any representation as for the

completeness or the accuracyof the infor-

mation contained herein, and disclaim

any liability for damages or injuries,

whether caused byor arisingfromthe lack

of completeness, inaccuracies of the in-

formation, misintepretations of the direc-

tions,misapplication of the information, or

otherwise.

surface due to th e polariza

tion of surrounding ai r mol

ecu les b

etween

the emitter

n e

edle

a n d

g r oun

d.

T h

e

elect rons collide

w it h t he

air

mol

e

cul

es a n d p r o d u ce

negat ive io ns .

A co mmo n misc onc ep

tion reg

ardin

g

high

-voltage

corona

or

arcing is that elec

trons

ar

e overcrowded on

the tip , and

forced

off by

mutual

r

epulsion

. What ac

tually

causes corona is

th e

high electric field

at

th e tip.

w hich is direct ly propor

tional to

th

e voltage. and is

enhan ced by

sharpenin

g

an

electrode

ti p

to a fine

point

.

T h

e

h i

gh electric field

s trains th e air

mo lecules.

polarizin

g them by a

phe

nomenon call

ed

dipole po

larization. If

th e

electrode is

positive. electr on s are lite r

a lly ripped of f,

c re a ting

positive

ions. or if th e elec

t ro d e is ne gative . they re

forced

to accept electrons.

creating ne

gative ions

.

High-voltage supplies like

those in TV s

need

careful

design , so

no

undesired dis

c o n t i n u i t i e s l i k e

s r

p

p oin ts o r edge s cause

arc

in g. However. for th e nega

tive

io n

generat or d iscussed

here. th e goal is to generate

corona,

no

t to

avoid

it. and

th e high electric field in the

vic in i ty of a discontinuity

more readily polarizes

and

i

onizes

air

molecules

.

The reason

fo r

th e hi gh

electr ic field at the

ti p

of

needle is du e to it s sma lllocalized

radius of curvature. A sphere has

a

mu

ch

more

uniform

e

lectric

field

at

its

surface, due

to

it s

co n

s tant and

mu ch larger

radius.

The audible

hiss

caused by a

high-voltage di scharge is ca lled

co rona

wind.

and is often

heard

in older la rge-screen color TVs .

es pecially on humid

days

. wh

en

t

he br

eakdown potential of th e

»

su

rr o

und in g a i r is

reduced. mak

- z

ing th e flyback t rans former a rc. j;

You can often

also

feel it . if

th e

corona is strong enough .

Th e

negative

io n generator de-

4


2/4

C2

1 ~ I F

04

1H4148

03

1N4148

R2

2200

.-

_

+

lM317T

TIP 8

~ ~

OJO

UT

IN

B C E

normall

y

quit

e small, while th e

flyb ack

tr

a n s f o r m e r ou tp u t

windin

g

norm all

y

h as ab o u t

2000-2500

turns . inducing - 3

to - 4 kilovolts .

Sinc

e

th

e ne

gative io n

gener

ator

nee ds to

produc

e - 9 to

- 1 4

kilovolts DC, a ladder voltage-trt

pIer

with

six diode-capacitor

rungs is u

se d

to half-wave

rectif

y

and

multiply

th e

flyback t

ra

ns

form

er output

voltage. I ts oper a

t ion

is b e s t u n d e r s t o o d in

R4

5600

02

1

8

1.. 1

+ - - -,1

4 L ~ L N E S2 : \

D CELLS)

07

SK3067/502

C5

.001

lEOl

BATTERY. :

01

OPERATED :

ft

9VAC-

- - - - ......- 02 Cl

1H4004 1000flF

C4 C3

-+---....-.-

.001 .001

H ~ h

09

SK3067/502

010

SK3067/502

.001

E

MITTER

NEE

DLE

ISEETExn

USE

EARTH GROUND

IFBATTERY OPERATED

fu n d a

m e n t a

l

fr e q u

e n cy w as

23. 26 kl-lz, altho

ug

h hi

gh

er har

monics gr e

atly

exte

nd th e to tal

b

andwid th

. Al

so ,

t

he

p

eak

-to

pe

ak b if tla r prim a ry winding

voltage is fou r ti

me s that

of

th e

supply.

Th e

as table sq

ua

re wav e in

duc es voltage

into

t

he

flyback

t r a n s f o rme r

o u t p u t

Wind ing ,

proportional

to

th e

t ransformer

t u r n s

ratio . A flvb a

ck tr an s

form

er

bifilar

primary winding

is

FIG. 1 THE SCHEMATIC OF THE NEGATIVE ion generator. T2 is a TV flyback trans

former; only its output winding is used, and new feedback and bifilar primary windings

are woundon the ferrite core. The bifilarprimary winding goes to the collectorsof astab le

1 2. Its square wave induces high voltage into the flyback transformer output winding,

boosted followed by a ladder voltage-tripler - 9 to - 14 kilovolts.

v

TO FLYBACK TRANSFORMER

FERRITE

CORE

FIG.

2

THEPARTS-PLACEMENTDIAGRAM

for

the main PCboard ; 01, 02, and ICl have

U-shaped 1x l inch copper heatsinks, with silicone grease for heat transfer; each goes

on the main PC board without insulators. In the prototype, Sl , S2, Fl, and NEl were

omitted, and T2was salvaged from a small-screen TV; note the new feedback and bifilar

primary windings. Pin 7

had the highest resistance relative to the flyback transformer

output lead, so it becomes ground.

The

circuit

Th e

sc

he

ma t ic of

th e

neg

at

ive

io n generator

appears

in Fig. 1:

T2 is a TV flyback transf

ormer

with

an open

ferrite core partially

enclosed in an

aluminum brack

et.

Th

e only

original

connections

used are on e low-voltage tap as

I ground. and th e lead

connecting

to th e flyback

transformer

out

put winding

at r ight).

T he o t h e r low-voltage tap s

a re n t u se d.

and

the ne w

feed

back and bifilar p ri ma ry w in d

in gs are

wound on

the ferrite

core.

Th e bifilar primarywindin

g

goes

to

th e

collectors of

an

asta

ble multivibrator

made up

of Ql

an d

Q2. w it h t he center ta p

dr i

v

en by

the

+3 - 5

vo lt s DC

from

ICI.

Th e a sta bl e e ne r

gy-

stor

age

e l em e nt s a re t h e i n du c ta n ces of

th e n ew feedback

an d

bifilar pri

mary windin

gs.

Th

e term bifilar means a

pair

of

transformer

windings

optimally

coupled by having been wound in

th e

same direction. either

adja

c

ent

to

or

. preferably.

superpo

sed

on top

of

on e

another

.

Th e

f

ee d

back winding goes

to

th e bas

es of

Ql and

Q2 for positive feedback.

w it h t he c en te r t ap driven

by the

+

3 -5 volts

DC

from

ICI

through

R3.

Th e

transistors ar e

then

for

ward-biased by

th e opposite en d

s

of

each

halfof

th e

feedback wind

ing.

When power is applied. the cur

rent

through

Ql and Q2 is une

qual, d u

e

to

diff

erence

s

in

dopin

g . la

yer th ick n

ess .

an d

base-em itter B-El turn-on volt

age. That s

what

c

ause s

oscilla

tion

; if all

th

e

astable

p

art

s w

er

e

perfectly balanced nearly

impo

s

s ible , it mi ght

not

oscillate at all.

Wh i ch

ev er

t r a n si st o r ca

r r

ie s

hi

gher

current

saturates

du

e to

positive base feedback. and the

other

cuts

off.

Wh

en

t

he sh arp in cr

ease

in

transistor current i n h al f

the bi

fil ar p r i m a ry winding is max

imiz ed . t h e induced vo ltage

revers es

.

so

the

second

tran

sisto r co n du cts and th e

first

on

e

cuts off.

Th e

collector waveform

scribed h ere is low-cost.

ea s

y to

build. and u s

es

a high-voltage

flyback transformer from an old

black-

and-whit

e

TV.

It ge

nera

tes

hi

gh

voltage . but at very low cu r

r

ent.

However.

th e

safety precau

tion

s

ta ke

n for a

ny high -

voltage

device s hould

be

observed h

er

e.


3/4

l

SILICO NE

RUBBER

AC output

waveform

from

th e

flyback

transformer

is coupled to

th e anode of 07 via C3

and

C4,

where 07 charges C4 . The

action

is repeated again via 09 , which

chargesC5 .The DC

potent

ials

on

C3-C5

add tripling the voltage

from th

,e flyback transformer

Winding. The anode of

010

is the

output

of

the

negative ion gener

ator,

and

should

be

at

- 9 to - 14

kilovolts DC.

Power is supplied by either a

standard full-wave rectifier fol

lowed

by variab le voltage

reg

ulator

ICI , or four

series 0

cells

producing 6 volts DC. Although

SI S2 FI

and

NEI

are

s

hown

in

Fig . 1, t

hey

were om i

tted

in the

prototype . ICI co

ntro

ls th e DC

voltage fed to th e oscillator via

Rl . Since t

he

negat ive ion gener

ator outpu t must be - 9 to 4

kilovolts ,

and

the exact flyback

transforme

r

turns

ratio

is

nor

mally

unknown

adj usting RI is

mandatory.

Once

RI is

set

the

negat ive ion

gene

rator output

voltage will be

stab

le.

o r

;:[

NPUT

FROM

I I

FLYBACK

I I

TRANSFORMER : 07 I

(MAIN

BOD

Y : f 08

WINDING : r

J

CARR IESHVDC) I :

1

~

i *

I r

I I I

I I I

C6 C7i,

:

HVDC

OUTPUT

0

..l

FINAl

HVDC

TR1PLER

OUTPUT

RUBBER

TE

STL

EAD

FL

YBACK

OUTPUT

RUBBER

TEST

LEAD

-I

RES IN t -------.

EMIITER

l _

NEEDLE

e,

:>

2

C

FIG. 4- THE NEGATIVEIONGENERATOR,showing the case, T2, plastic soda bottle, and

the top of the high-voltage PC board , wit h 05, 07, 09, and C3-C8. Both the plastic soda -<

bottle and high voltage PC board are held in place with RTV The neck is sealed with

I

casting resin to wit hin

Yo

- inch of the top; cover the needle with a cork when unused.

FIG. 3 THE PARTS-PLACEMENT di

agram for the high-voltage PC board. The

parts shown include high-voltageceramic

disc capacitors C3--C8, and selenium rec

tifiers 05--010. 05, 07, and 09 go on the

component side (solid lines), whi le 06,

08, and 010 go on the foil sid e (dashed

lines) .

segments . The AC

waveform

from the

transformer is coupled

to

05

and

06

via C3 charged

through

05

act ing as

a clamp.

The

peak-to -peak

magnitude

of t

he

AC

waveform

at

th e

anode

of 05 equals that of the fl

yback

transfo rmer

outp

u t Winding

wit

h a negative DC

component

of

half t

he

peak

-to

-peak value.

The

NOTE:The fo llowing are available from

Anthony J. Car

isti

, 69 White Pond

Road , Wald wick, NJ 07463: Two

etched and dr illed PC boards (one

each for the main and voltage-tripler

sections) for $15.95, IC1for $3.25, 01

and 02 fo r $2.75 each. Please add

$2.00 for postage and handling with

each order; NJ resid ents please add

7% sales tax.

Semic

onduc

to rs 01, 02 1N4004 sil

icon diode

03, 04 1N4148 silicon diode

D5 01o RCA SK3067/502 high-voltage

diode. 12 kilovolts PIV

LE01

l

ight-emitting diode for the bat

tery-operated version

01. Q2 TIP31B NPN transistor

IC1 LM317T adjustable voltage

regulator

Other components

F1 Q.5-amp slow-blow fuse with holder

NE1 120 volt AC neon-bulb assembly

with 47-100K built-in series resistor for

the p lug- in version (Radio Shack

272-712)

NE2 neon bulb, type NE2 (not the part

number). optional for experiment (see

text)

S1 SP sT toggle switch

S2-S PST toggle switch

T1 18 -volt center-tapped transformer

(RadioShack 273-1515 )

T2 standard TV f lyback transfo rmer

(see text)

Capacitors

C1 1000

tJ.F, 25 volts, electrolytic

C2 100 tJ.F 16volts. electrolytic

C3 C8 0 .001

tJ.F, 10 kilovolts, ceramic

disc

C9 0

.001 tJ.F, 500 volts, ceramic disc,

optional for aluminum can/neon bulb

experiment (see text)

M is cel laneous :

Plastic

case

(7.5 x 4.25 x 2.25-inches, RadioShack

270-224), enamel magnet wire, three

wire line cord, emitter needle (made

from either straight pin or sewing nee

dle), RTV silicon rubber, heat sinks, four

alkaline 0 cells (optional for battery

operation), 2-liter plastic soda bottle,

and a sewing needle.

PARTS LIST

All resistors are Yo-watt , 5%, un less

otherwise noted.

R1 1000 ohms, PC-board mounted po

tentiometer

R2 220

ohms

R3, R4 560 ohms (the former for the

astable-flyback transformer combina

tion, the latter optional for the battery

operated version)

R5 R6 200 - and 40-megohm series

h igh vol

tage

f ocus d iv

ide

r, RCA

SK3868/DIV 1 , used for an optional

high-voltage range extender for a con

ven tional h igh impedance (10

megohm) voltmeter (see text)

R7 2 7 megohms


4/4

FIG. 5-THE BOTTOM OF THE HIGH-VOLTAGE PC board, showing 06 , 08 , and 010, and

the attachment points of the

ground

lead and both high-voltage leads.

Construction

Next,

we

ll di s cu s s

co

n

struction , foc

using

on the ma in

and vo ltage-trip le r PC

boa

rds ,

th e plastic cove r for t

he

voltage

tr

ip ler PC board made from the

top third of a 2-liter plast ic soda

bottle, the em itter n eedle , an d

t

he

cu to

ut

in

th

e

lid

of

th

e plastic

case for the flyb ack transfo

rm

er.

Fig

ure 2

shows

th

e p

art

s-place

m

en

t diagr

am

for t

he

m

ain

PC

board , and Fig . 3 the ladde r volt

age-tripler

sectio

n . R

em

emb

er

to

add S I , S2, FI , an d NEI off the

m

ain

PC bo

ard,

as s hown in Fig.

1, if you want th

em

.

Th

e main

sec

tion

includ

es

th

e

re

gulated

supp ly, oscillator, and

flyb

ack tran

sform

er

, an d goes

on

th e s ing le-s ide d PC bo

ard

men

tion ed in the parts lis t , wit h the

fo il p attern s h own h ere.

Th

e

h igh-voltage PC board conta ins

t

he

l

adder

vo

ltage

trtpl

er

, con

nec ted to the ma in PC board by

two le

ad

s , an d t

he

em

itte

r n eedle

is ab ove th e hi

gh-

vo

lt

age PC

bo

ard.

In Fig. 2 , QI , Q2 , an d ICI

n eed

heat

sinks ; you can buy

th

em, or

m

ak

e th em

from

1x l

in ch

copper bent

in

a U, with

s ilicone g

rease

for h eat trans fer.

The h ea t s in ks go on top of t

he

PC bo ard

wit

ho

ut

i

ns

ula to rs .

Neon lamp

asse

mbly NEI

acts

as

a n in i c a t or ,

n

h a s a

47

K- 100Kresis

to r

in se ries with

it . For ba tt

er

y op

era

ti

on

, u s e

L

EOI

in

se

ries

with

R4; u se al

kaline ba

tt

eries,

not

ca rbon-zi

nc

.

Us e a 3-wire cord with ground , or

an ea r th ground in

batt

ery-oper

a ted versions. The voltage-tripler

se ct ion is

built

to avoid a rc i

ng

and

sho

ck. Cut t

he

top th ird off a

2-li ter pl a sti c

soda

bo

tt l

e ,

as

shown

in

th e le

ad ph

oto ,or u se 4

in ch d iam e t

er

pl a s

ti

c PVC

plumbin

g pipe.

Use 18- gauge rubb er-co

at

ed

test

l

ead

s to con

nec

t t

he hi

gh

vo ltage PC bo

ard

to b o th the

flyba

ck tran

s f

ormer outpu

t

and

th

e n e

edl

e, to

withstand

h i

gh

vol

tage,

but n

ot until indi

ca ted

(more below).

Th

e h eavy voltage

t ripler ou tp u t lead is so ldered to

the e

mitte

r n eedle , which goes

upward through the plastic soda

b o

tt l

e an d

pr

oj ec ts o

ut

of t

he

n eck, which is filled wit h casting

re

sin

. Don t fill t

he

ne

ck

wit h res

in all t

he

way to th e top; leave

inch of the n eck open, so you can

cap

th

e needle with a wine bottle

cork

when

not

in

use.

08

06

FIN L

HVDC f oiE

OUTPUT

Th

e v

ol t

age t ripler s

how

n in

Fig. 3 co

ns

is

ts

of ceramic di s c ca

pacit

or

s C3

-C8

, a n d

hi

gh -

volt

age selen ium rectifiers

05-010

.

Note that 05 , 0 7, and 0 9 go on

t

he

compo

nent

s ide of t

he

PC

boa rd , whil

e

D

fi.

0 8, and

010

go

on the foil

sid

e. They re common

to

most

TV s , so

most

TV repair

s

hops should

s tock them; see

th

e

parts list.

Fi

gur

e 4 sh

ows

a

phot

o of t

he

negat ive ion ge

ne

ra tor, wi

th

the

closed case , flyba ck transforme r,

plas t icso

da

bottle, an d top of t

he

hi

gh-voltage PC board show i

ng

05

,

07

, 0 9 , a n d

C3 -C8

.

Th

e

hi

gh-

voltage PC bo

ard

is h eld in

place ins id e t

he plasti

c so

da

bot

tle top using RTVs ilico

ne rubb

er,

and th e

pl a

sti

c so

da bottl

e goes

on th e top of

th

e case

th

e same

way, for a water-tight se al that

avo i

ds

con

de

nsa

ti

o

n,

a

nd

h as

good high -voltag e att r ibutes .

Th

e markings and s izes of the

hi

gh -voltage TV diodes used in

t

he

vo

ltage tripl er di

ff

er

from

t hose on s t n da r d

di

od es.

Th

ey r e

much

l

ar

g

er

, and h ave a

very

high

peak-inverse vol tage

(PIV) ra ti

ng

. Also, on a conven

ti

on

al

diod

e,

th

e cat h ode is n or

m all y m

ark

ed with a b and ,

wh

eth

er a wh i te b

and

on a black

body for such low-voltage rec

ti fi

er

s

as

t

he

IN4

00I

, or a r

ed

band on a clear glass body, as

wi

th

t

he

IN4148

or

IN914 .

In high-voltage TV

diod

es, the

body

is ge

nera

lly either wh

ite,

bla ck , or see-t

hroug

h. In Fig . 4,

05

and 07 are whi te wi th a b

and

of bla

ck

s ig

ns on th

e r i

ght

end , while 0 9 is bl ack with a

FL

YB

CK

OUTPUT

UNDERSIDE O

VOLT GE TRIPLER

P BO RD

GND

WIR

dashed

band

of wh ite - s ig

ns

on the righ t en d. The en

ds

wit h

t

he

b

and

s

ar

e t

he ca

t

ho

des

, f

or

both diode body types ; t

he

reason

for t

he

s igns on 0 3

and

05 is

th

at circu

it

power is

norm

ally

co

ns

ide re d as b eing

ex t

racted

from

th

e c

athod

e en

ds

in

TV,

and

is ca lled B . In Fig. 5 , 06 , 0 8 ,

and

010

all h ave bands of

s ig

ns

on th e ca thodes .

A 3 x 3-inch hole was made in

th

e case top for t

he

flyback trans

f

ormer

; adjust you

rs

as needed.

Dori t con

nec

t the voltage-tripler

PC board to the mai n PC board

un

til t

he fin

al c

hec

ko

ut

below;

pu

t it

as

ide and let t

he

RTV dry

overn i

gh

t .

Th

e so

da bottl

e and

the hi gh-voltage PC

board

a re

h eld in place u

sin

g RTv.

Th

e

rub

ber-co

at

ed test leads con nect the

fl

yb

a c

k-tran sformer ou

tpu t to

the voltage tripler and the voltage

tr ip le r to the em itter n eedle; t

he

th in wire is t

he Q

round.

A flyback transforme r is also

ca lled a tu ned

tran

s fo

rm

er, and

co

ns

ists of a ferrite co re s u r

ro

und

ed by a metal

br

a

ck

et, with

a l

ar

ge coil of windings coated in

pl a s ti c o r cer

ami

c

with

a n

x

m y

hi

gh

di ele

ctric

br

e

ak

down vol

tage

. Oft

en

,

as

wi

th

t

he

flyback

tr a

nsfor

mer

used in the

pro to type , t

he

re are add

it

ional

low-voltage o

utp

ut windi

ng

ta

ps

(seve n , in that ca s e ) p

laced

a round a plastic

ri n

g on o

ne

s ide

of the tr a

ns

f

ormer

coil, that have

equally h igh-voltage

br

eakdown

characteristics .

That s all we have room for.

Next m

onth

we ll fini

sh up

th is

project. R-E

Páginas DesdeRadio Electronics January 1991

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