fun electronics projects for the experimenter (1)

8/20/2019 Fun Electronics Projects for the Experimenter (1)

1/189

r

ths

illu|EII

F-

F d

6 1 1


2/189

rurProlcGB

lr tln

hoilmomtl

During

more han

20

years,

he author,

s

a

collaborator

ithAmerican,

European

ndLatin

Americanlectronics

agazines*,

as

published

large

assortment

f

practical

ircuits sing

ommon

arts.

Nowmany f those

projects

re ncluded

n thisvolume,mostof

which

ou

canbuild

n

one

evening.

he

projects

angerom un ypes hrough

ractical

types

o amusement

ypes.Of course,

hereareotherdevices

hatcan be

used o

teach

ou

something

bout ircuits r components.

An mportant

eature

f

heses

rojects

re

he deaso

Explore,ntended

or

students

ooking

or

projects

n

science r

o use n

practical

esearch.

We

can

considerhisbook

as a source ookof

theeasiest nd

un-to-make

of he

hundredsf

projects

reated nd

published

y

heauthor uring

hese

last

years.

But,as

the

projects

re

n a wide

angeof types,

we

should eparate

he

electronics

xperimenters

nto wo

groups:

heones

whowant o

improve r

expand

omeotherarea

of theirelectronics

nterest, uchas

computers,

radio,nstrumentation,

udio, ecurity nd

even

games;

nd

he ones

who

want o

learn omethingbout

electronicircuits nd

devices r

want

new

ideaso

use

n science

rojects.

Most f heprojectsescribedereinanbestand-alones ndividualcces-

sories;

herever

ossible

he

circuits

ave een esigned

o hat

hey

an

be

ganged

ithoneor

more ther

rojects.

orexample,

any

rojects

f audio

etfects r

generators

anbe

ganged

ith

audio mplifiers

r

high-powerut-

put

stages.

All

he

projects

resimple,

ith

ew ow-cost

omponents

hatcan

be

maden

oneevening f

work.

Tomake t easy or he readero chooseheprojects eadded odes fter

each

itle o ndicatehe

kind

of

experimenterfor

homheyare

ntended:he

code

P

(Practical)

ndicates

project

uilt or

practical

se.

Thecode

E'

(Experimental)

ndicateshat he

project

s intended

or

heexperimenter

o

teach omethingbout

ircuits r devlces.


3/189

trolrcc

Of course,

ou

can

also

ind

projects

with

both codes

E

and P)which

an

dther

be mounted

o teach

something

rknd

be used or

a

practical

nd.

The

presentations

f the

projects

re

practical.

lectronics

omponents

re

listed

with

each

circuitdiagram.

ut

secondary

arts

such

as sockets,

has-

sis,enclosures, iscellaneousardware nd so on, are not

specified, ince

the reader

s

free o

choose hesenon-critical

tems

according

o

his

prefer-

ences

and demands.

The

manner n

which he

circuitswork

and

can be modifieds

explainedn

practical

erms

so the reader

an

acquire

ome

knowledge

f

practical

lec-

tronics

as he

progresses

hrough

he book.

Although

many

of the

projects

we

enjoyed

onstructing

s heyaredescribed

here, oumay hinkof possiblemodifications.e ustrecommendhatyougo

aheadand modify

he circuits

o

yourpersonal

nds.There s

a

wide

atitude

in

circuitmodifications

nd

most

of

them

will

be of

value

o

the experimente

who

wants

o see how

hingswork,

even hough

each

project's rimary

ntent

is or

he

builder

who

desires functional

tem

of equipment

s he

result

f his

work.

As

the

book

ncludes

asy-to-build

rojects,

he

authorhopes t

will help

you

to learn

many

of the undamentals

f electronicsn

an

easyand

un

way,

and,

if you'rea student, rovide source orschoolprojects.

Newton

C.

Braga

.

Mini-Projects

s

he itle

of a column

ublished

y heauthor

uring evera

years

n

a

Brazilian

lectronics

agazine

amedEletr6nicaTotal

Total

Elec-

tronics).


4/189

frnFdocahlhclnulmtmol

MlcRo-PowER

EDFLASHER

E/P)

A simple

LED lasher

an be built

witha TLC7555 imerusedas a low-

frequencyscillator

nd

drive o an

LED.

C1 uns n a

low requencyeter-

mined y

R?R3andC1.

Frequencys n he

ange etween.1

and5

Hz

but

you

canalter

t bychanging l.This

capacitor

an

angerom

1

to

10uF.

Duty ycle

sdeterminedy

R2/R3

atio

nd

s mportant

napplications

here

you

need eductionf

energy onsumed.Though

igure shows

ixed

esis-

tors

or R2

and

R3,

you

can

use rimmer

otentiometers

f

youprefer.

he

potentiometers,fcourse, rehandyoralteringhe

requencyndduty

ycle

of theoscillator.

Rl values epend

pon

he

power

upply

oltage.

With

power

upplies

e-

tween

and6

volts,R1

s 470

ohms.

With

power

upplies

etween

and9

volts,

Rl is

560

or

680

ohms.

With

power

upplies

n he ange etween

and

12volts,

l must e

1,000

hms.The

ircuit rains nly

50uA

rom 6-vol

power

upply.

Figure

showsheschematic

iagram

or

he

Micro-Power

ED

Flasher. t

the

heart f hecircuit

s Ol,

a 555

imer.

Use

he

partsplacement

iagram s

a

guide

whenassembling

he

Micro-

Power ED

Flasher. omponents

lacement,

sing

terminal trip

as chas-

sis,

s shown

n Figure

2.

Take pecial are

with

positions

f

polarized

omponents,

uchas

the

LED

andelectrolytic

apacitor.

After ouaresure hatyouhavewiredall hecomponentsorrectly,ut he

batteries

n

hebattery

older. heLEDshould

lash.


5/189

R1

560s,

c1

4.7pF

Dl

Rg

1N914

4KT

Figure

I

H. lGt t@

l {

Figure

2


6/189

mtnfffifrtchrmlffi

PartsList

-

Micro-Power

EDFlasher

lC1

-

TLC7555CMOS

ntegrated

ircuit

Timer

LEDI - Commoned,greenor yellowLED

D1

-

1N914

general

urpose

ilicon iode

Rl

-

560

ohm,

114W,5%

esistor

R2

-

1,000,000hm,

114W,5%

esistor

Rg

-

4,700ohm,

114W,5%esistor

C1 - 4,7 uF,6 M/DCelectrolyticapacitor

C2

-

10

UF,

2

W\/DC

electrolytic

apacitor

81

-

6

to 12VAA cells,9V

batteryor

power

supply

ldeas o

Explore

learnmoreabout

he circuitand devices:

o

AlterR2and

R3

(minimum

alues

re

1,000 hms

or

both)

andsee

how he

lashing atechanges.Of course,

f

you

want,

you

can

replace

R2

and

R3 with

1,000,000-ohmrimmer

potentiometers.

o Explain ow he astable 55works n this circuit.

o

Alter

C1

n a

rangebetween and

100

uF and

observe

lashing

ate

alteration.

xplainwhat

happens.

o

What

s

duty-cycle?


7/189

FroFGtl

lmPomrlMmficr

Science

xperiments

ith

he clrcuit:

o

LED

s

a monochromatic

ight

source.You

can

perform

ome

ex-

periments

n

optics

using hiskind

of light

source.

Chromatic

ilters

an

be used n

some

experiments

nvolving

EDs.Tryto

se

LEDs

of differ-

entcolors red,yellow, reenand, f possible, lue).

.

Light lashes,

s the

ones

produced

y this

circuit,

an be

used n

hypnotic

xperiments.

o

The

circuit

can

be used

o indicate

operation

f

otherelectroni

devices.

Wired

o

the

power

supply

of

a

monitored

evice,

he

blinker

LEDwill

ndicate

ts

operation.

Rememberhat he heoryn hisbook sspecificallyelatedo theassociated

experiments

nd

projects.This

ook s

designed

s an ntroduction,

ot

as an

in-depth

reatment

f electronics.

f

you

are interested

n

finding

out more

about he

subjects

ouched

on

in

this

book,

several

exts

can

be

found

or

further

eading.


8/189

frnPrrre$hrfiosrrhdlu

SET-RESET

LIP-FLOP

E)

With

his

pQect

we can

show

how

wo

NAND

ates

f a

7400

C

(TTL

nte-

grated

Gircuit)

an

be

wired

o

perform

s an

R-S

lip-flop.

This ircuit

sa

pulse-triggeredlip-flop

hat

needs

egative-going

ulses

o

be

triggered.

his

circuit

perates

s

follows:

s

we see,

t haltwg_outngls;

nolmd

output

alled

(LED1)

nd

an

nverted

utput

alled

(LED2).Whe

one

output

s 1 he

other

ecessarily

illbe0 and

ice-versa

ecause

heyare

complementary.

Thecircuit

asalso

wo

nputs

amed

(SET)

nd

R

(RESET)

s shown

n

theschematic

iagram,

here

he

rigger

ignals

re

applied.

R nput

s

wired

o

Q

output

nd

S

nput

s

wired

o

Ooutput,

orming

closed

loop

or hedigital

ignals.

When

negative-going

rigger

ulse

sapplied

o S

nput

heoutputQ

swingi

to the

1 staie.

As histutput

s wired

o

R nput,

he

1 state

auses

utput

Q

to

all o a 0

evel.

ut

Q

output

s

also

wired

o S

nput ausing

feedbackth

makes

tsoutput

emain

t

1

also

atter

he rigger

ulse

asdisappeared.

o

trigger

he

lip-flop

gain,

hanging

he

output

tates,

eshould

pply

nega

p -goingpulseoR nput.Thisulse ausesheoutputogo o1 andas his

output

s

wired

o R

nput,

he rigger

ulse

lso

causes

he

outputQ

to

go

o

0level.

Azero

n this

output

oes

o

R input,

ndalso

after

he

rigger

ulse

isap

pears

heoutputs

emain

n their

states.

See

hat

he circuit

as

wo stable

tates,

nd

we

only

can

change

hese

states

withset

or

reset

S

or

R) negative-going

ulses

pplied

o

its nputs.

Our

project

s a

manually-triggered

lip-flopndcanbeconstructediring

switch

o

the

R-S

nputs s

shown

n Figure

1.

Logic

tates

re

ndicateqby

wo

LEDs.

ED1

lows

witha

1

at

Q

output

nd

LED2

lows

with

a

1

at

d

outPut.


9/189

Ffd0crz

sH-i$fff,llHrr

The

circuitmust

be

powered

y

a S-voltegulated

ower

upply

s t

usesa

TTL

C.

Currentequirements

ange

ypically

rom

5 to

15

mA.

Components

lacement

n

a small

rinted-circuit

oards

shownn

Figure

.

Experimentsike hiscanalsobeperformednwhatelectronicsxperimen

erscall

breadboards".

These

reboards

n

which

he

parts

of experiment

can

be emporarily

ssembled.

y

using

readboards

t is

notnecessary

o

teo\/7

$1"

t'\tt

ffin

Figure

I

Figure

2

r8


10/189

Frndrctrffithe halmffil

solder

he

components.

his

s

why hey

are

also

called

solderless

boards"

The

circuit

an

be

used

o

teach

much

about

lip-flops,

sed

n computers

s

counters

nd

n

memories

nd

many

other

applications.

Observation:n digitalelectronics n electrical ignal s eitherhighor low.

These

wostates

ale

used

o

represent

inary

bits

1

and

0.

Since

digital

ogic

lOs operate

rom a

single-ended

ower

supply,

a

high state

represents

voltage

ear

he supply

oltage

nd

a

lowstate

epresents

voltage

ear

0V'

Panrs

Lsr

-

SET-RESET

UP-FIoP

fC1

-

74OO

TL

Integrated

ircuit

LEDs - Red,greenoryellow ommon EDs

R1,

R2

-

330

ohm,

114W,5Y"

esistors

51

-

SPDT

toggle

switch

ldeas

o

ExPlore

To

earn

more

about

he

circuit

nd

devices:

o

The

common

lip-flop

s

a

fundamental

ounter

ircuit.

Mount

ther

units

ike

his

and

use

hem

o explain

owcounters

nd

memorie

work

n computer

ircuits.

ach

lip-flop

an

store

a

bit.

.

Find

he

ditferences

etween

-S

and

J-K

lip-flops

nd

how

hey

are

used

n

ogic

ircuits.

Science

xperiments

nd

projects

sing

his

circuit:

o

Replace

1

by

a-magnetic

reed)

witch

r a

microswitch

nd

use

thiscircuit

s

a one-event

emory

n experiments.

t can

detect

nd

memorize

hen

a Switch

n an

ure,

alarm,

r

mechanical

rocess

s

closed

ora

moment.

-

tf


11/189

Hn

ProfmBf

ilo lrnulmrnml

MIN|-METRONOME

P)

Heresa dandywo-transistoretronomehich oucanbuildntoa sma

plastic

ase.

You

can

usean old

nonworkingransistor

adio o

house his

gadget.

n mostcase

you

can

merely emovehe

main

circuitry

ut

retai

some

parts,

uch

as the on-otf

olume ontrol

otentiometer,

peaker nd

battery

older.

f

you

havedone his,

you

have

ust

eliminated

he ollowin

items:

PKR,

1,and

81.

Thecircuit anbe

powered

ith woorfourAA ells

nddrains bout

0mA

Assoonas 31 isclosed,hemetronorfletbrtq lacking.yadjustingoten

tiometer

1

you

ind he

beat'or

frequencyf clacking

ou

wish o set.

Tocalibrate,

ou

have nly

o synchronize

our

metronome

itha commerc

type

or any

known ource.

Figure

shows

he

schematic

iagram

or

he

Mini-Metronome.

t he

hea

of

thecircuit re

Q1

and

Q2,

as a

two-stageirect-coupled

mplifier,

hic

allows

hecircuit

o

generate

ntervalled

ulses.

Figure

2showsa

mechanicalviewf

themetronome,

sing

terminal tri

as

chassis

for hesmall

omponents.

Position f

the

polarized

omponents,

uchas Gl, C2

and

he transisto

should e

observed

n hemounting.

rt


12/189

;fdcr8

ilrl-IrEwm

Q1

R1

10K

*_J

Q 2

| s t \

Bc5s8

| t

t l

c 2 d

I

100pF

T I

I t ?

l a r :

|

3/6V

T-

SPKR

4l8A

+ r \

c1

lOpF

R2

1 K

P1

1 M

Ftgure

1

Figure

2

\

t0


13/189

HftFCIFfrilTtrlffiHT

-

- --

Parts

List

-

Mini

Metronome

Q1

-

8C548

NPN

ransistor

Q2 - 8C558 PNP ransistor

51

-

SPST

toggle

or slide

switch

81

-

3V

or 6V

-

two or

four

AA cells

SPKR

4 or I

ohm,

2

to

4-inch

oudspeaker

P1

-

1,000,000

hm

Potentiometer

Rl

-

10,000

hm,

1l4W,5olo

esistor

PA

-

1,000

hm,

114W,5%

esistor

C1

-

10

pf,

6

VVVDC

lectrolytic

apacitor

C2

-

10

Uf,

6

WVDC

electrolytic

apacitor

ldeas

o

ExPlore

To

earn

more

about

he

circuit

and

devices

r

to

get

better

performance:

o

Replace

1

by any

capacitor

n

the

range

etween

and

10

pF

Observe

hat

will

happen

o the

beat

ate.

Explain

t'

o

Replace

ransistor

2

withaTlP32

on

a small

eatsink

nd

powe

thecircuit

rom

a 9V

or

12V

power

upply.You'll

ave

extra

ower

or

your

experimental

etronome

nd

can

use

t

in

arger

laces.

o

.

Remove

Pl

and

ouch

with

your

ingers

he

points

where

t

was

wiied.

Will

he

circuit

perate?

an

you

explain

hat

s

going

n?

-

2a


14/189

Prtlm8

thl-ilrtrrnrm

Science xperiments

nd

ditferent

ses or he

circuit:

o

The

metronome

an

be used n

gymnastic

xercises

r

n

running

to find

he

correct

hythm.

hemetronome

an

be

housed

n

a smal

plastic

ox,

powered

ycells

andeasily

arried ith

he unner.

o

Biological

xperimentsith

sounds

an

be

made

with his

device

experimentsn

animal

onditioning,or

example.

n


15/189

filnH.f0c03ffisrhoilm

PENDULUM

LARM

(E/P)

Any

movement

hat

swings

he

pendulum

ensor

riggers

his

alarm,

nabling

a

relay.

Thecircuit

an

be

used

o

protect

ars,

arge bjects,

omes

nd

other

laces

as

he

sensor

an

be used

o detect

ny

movement.

hisdevice

an

alsobe

used

orscientific

xperiments,

s suggested

t

theend

of

thesection.

The

relay

andrive

powerful

ound

ystems,

uch

as sirens,

orns,

amps,

etc.

Thecircuit

an

be

powered

y

a

l2-voltbattery

when

used

n

cars,

or

instance)

r

a

power

upply.

urrent

rain

s

very ow

about

00

uA)

when

he

relay

s

deenergized,

xtending

attery

ife.

Theschematic

ircult

f

he

Pendulum

larmsshown

n Figure

.Thecircuit

hasas

its

heartan SCR

Silicon

ontrolled

ectifier),

hich

energizes

he

relay

when

he

sensor

etects

ny

movement.

A mechanical

iewof

thecircuit

mounting,

sing

terminal

tripas

chassis,

is shown

n Figure

2.

Relay oil

voltage

s chosen

ccording

o the

power

upply

oltage.

ou an

usea miniDPDT AMiniRelayRadio hack 75'249)r, orheavyoads,

10AminiSPDT

elay

Radio

hack

75-248).These

elays re

rated

o

12

VDC

and drain

only

38

mA

(their

oil

resistance

s about

320

ohms).

As

equivalent

ypes an

be

used,

ou

should

akecare

with erminal

ayout.

Reset an

be

made

witha

momentary-typ6

witch

Push-On)

ired

etween

theSCR

anode

ndcatode,

r by

using

heon-otf

witch.

Positions

f

polarized

omponents,

uch

as

the SCR

and

diode,

hould

e

::t::r :tairs

are

atso

iven

n Fisurc2.

Norice

hatoperation

ccurs

hen

the

vertical

or

horizontal)

are

wire

ouches

he

ringduring

ny

movement

2l


16/189

fl0l0c|

Penilulumlhrm

(sEE

TEXT)

X1

R1

scR

Ttc106

Figure

I

Figure

2

'B


17/189

m'lrfrctstrhrhuffim

PartsList

-

Pendulum larm

SCR

-TlC106

requivalent

ilicon

ontrolled

ectifier

D1

-

1N914 requivalent

eneral-purpose

ilicon iode

K1

-

12V elay

see

ext)

S1

-

SPST

lideor

oggle witch

Rl

-

22,OOOhm,

114W,5%

esistor

R2

-

10,000 hm,

114W,5%

esistor

X1 - Pendulumensorsee ext)

ldeas o

Explore

To earnmoreabout

ircuit nddevices:

o

Replace

elay

with

a

12Y

200mA ncandescent

amp.Does

he

circuitwork?

o

Explain hat

Dl

is

doing

n hiscircuit.

s

t necessary

f he elay

s

replacedyan

ncandescent

amp?

o

Explain

owanSCR

works

Science

rojects

nd

ditferent ses

or hiscircuit:

o

Replace

1 by a

reed

switch

o

get

an alarm

riggered y

a

mag-

netic ensor.Youanalso eplace 1bf a microswitchr other indof

momentary

witch.

o

In

biological

xperiments

he alarmcan

be used

o detect

mal

movements

n animal

rapsor cages.

t0


18/189

Frfhct

?oildumllrrm

o

Replacing

l

by wo

metal

wires

enables

he

circuit

o

be riggered

by water.

Water

evel

detectors

an

be made

using

his kind

of

sensor,

and t

can

be used n

many

experiments

nd

practical

pplications.

o

lnstalled

n

your

car, his

circuit

an

be used

as an

alarm,

driving

hehornor a siren.

o

By replacing

1

with

a

large

metal

plate,

he

circuit

an

be used

o

detect

wind.

Air

low

can

move

he

plate

so

that

he

bare

wire

ouching

the loop

causes

he

alarm o

trigger.


19/189

runPnFctlollhEnul

MEDIUM-WAVE

F

PRESELECTOR

P)

The

sensivity

f

most

moderately-priced

M

eceivers

s

poor

n he

medium-

wave

and.

orse

yet,

selectivity

lso

drops

tf

sharply

ithin

he

upper

art

or

tn"

band,

making

ne

receiv-er

ighly

usceptible

o

images,

oise

and

annoying

eterodYnes.

Even

he

best

antenna

nd

a

good

booster

mplifier

an't

make

p

or

hese

deficiencies

n

a common

eceive/s

ront

end.

But,

using

n

RF

preselector

b;trd;

the

antenna

nd

he

eceiver's

ntenna

nput

erminals

ill

give

ou

realncreasen hereceptionuality.

This

ircuit

matches

he

antenna

mpedance

ith

he

eceive/s

ntenna

nput

according

he

requency

f

the

uned

tation'

Figure

shows

chematic

iagram

f

the

Medium-wave

reselector'

Figure2

shows

n

exploded

iew

of

the

circuit,

which

an

be

housed

n a

small

lastic

ox.

Ll

is

ormed

y

urns

f

No.28

enameledire,wound na 5/16-incherrite

form.

aps

re

made

ach

15

or

20

urns

and

ts

number

s not

critical'

he

number

f

taPs

an

be

altered.

Attach

our

antenna

nd

ground

o

the

nput

erminals

f

the

preselector

Tune

o

the

desired

tation

n

your

eceiver,

nd,

by

choosing

he

best.posi-

tion

of

the

alligator

lip

on

he

trip

anO

y

adjusting

V

find

he

best

signal'

The equired

ntenna

ill

depend

pon

he

station

ou

want

o

tune'

A

ran-

dom

ength

f

wiie

willgive airlygoodperformancehroughheA{ band'

Antennas

ith

engths

-etween

s

ano

150

eet

are

ecommended

or

best

performance.

-

tf


20/189

Filf0cr

5 tdhmtmtrlffiffir

A

G

To

Receiver

Figure

I

Figure

2

{

el

g l


21/189

HrfilFcNrtrffisuhM

- - - -

Parts

List

-

Medium-Wave

F

Preselector

L1

CV

X1

-

Medium-Wave

oil

-

see

ext

-

365

pF

miniature

ariable

apacitor

-

Alligator

lip

-

2-position

arrier

triP

ldeas o ExPlore

To

earn

more

about

he

circuit

nd

devices:

o

Explain

he

mportance

f

a

good

ground

onnection

n hiscircu

What

s he

meaning

f

"impedance"?

o

Use

a

newcoil

with

20

urnsand

apsevery

turns

o

tuneshor

wavestations.

o

Make

seoond

oil

20

urns)

n

hesame

errite

od o

plug

h

antenna

nd

ground.


22/189

ftnFillectiffimmlhleilcr

ELECTRONIC

ISHING

URE

(P)

This

circuit

mitates

he

sound

f

wet

bugs

milling

bout

he

surface

o attra

curious

ish.

The

circuit

s basically

Hartley

udio

oscillator

perating

n

a

frequen

between

00

and

2,006

Hertz.

Powered

y

an

AA

cell,

t can

housed

n a

clea

empty

eanut

utter

ar

with

he

buzzer

ircuitry

mounted

pside-down

n

h

.ofti.Vou

must

be

carefull

ot

o

drill

n such

a

way

as

o

allow

water

o

ea

tnrougn

he

cap.

ilicon

ubber

an

be

used

o

close

ny

water

eak'

CapacitorCl

ould

ive resonantfrequencyof

pproximately

,000

Hz'

b

p1

would

ive

a

wid6

ariation

n

signaltone

enerated

n

he

audio

ange

You

an

also

use

a

low-impedance

arphone

s

a

transducer,

onnecting

t

the

second

oil

output) f

the

ransformer'

To

operate,

nscrew

he

cap,

hrow

S1

ON,

put

he

cover

ack

on,

and

dr

the

ish

ure

nto

he

water

n ne

vicinity

f

where

ou

will

be

ishing'

llow

minuteseforeeelinghemn. f necessary,diustP1 oa new

signal

on

Figure

I shows

he schematic

iagral

for

the

Fish

Lure.

observe

hat

h

se-condary

oil

of

the

small

udio

ransformer

s

not

used

n

his

circuit.

construction

etails

f

the

Electronic

ishing

ure,

sing

terminal

trip

chassis,

s shown

n

Figute

2.

The

exact

ocations

f

components

s

n

critical.

T1 salsonotcritical.ny500:8

r

1,000:8

ransistor

ransformer

ith

en

tapped

rimary

an

be

used.

we

canalsosuggesthatanysmallransi

transformer

an

be

experimented

ith'

EO


23/189

Pnm

0

$oe[cnhHshlnf

un

S1

1.5V

(')

SEETEXT

R1

1 K

Figure

1

Figure

2

It


24/189

Fr}Idccufor[nHrcilmEmGl

PartsList

Electronic ishingLure

Q1

-

8C548

general-purpose

PN

silicon

ransistor

T1

-

500:8or 1,000:8ransistor

ransformer

(RadioShack2TS-1380s suitableor his ask)

P1

-

100,000

hm

rimmer

otentiometer

R1

-

1,000

hm,

114W,5%esistor

C1

-

0.01uF

metal ilm

or ceramic

apacitor

S1

-

SPST

oggle

r slide witch

BZ - Piezoelectricransducer r crystalearphone

(Radio

hack273-073r equivalent)

81

-

1.5V AA

cell

ldeas

o

Explore

To earnmore

about

he

circuit:

o

ReplaceBZby

a

low-impedance

weeter r small oudspeakeron-

nected o the transformer econdary

oil.

o

ChangeC1

values n

the range

between .001and0.22uF.

Ob-

servewhat hapenswith one

pitch.

A higher-value

apacitor

ives

a

lower one.

o

The circuitalso

operates

rom

a

3V

or

6V

power

supply

without

making

nychanges.

ft


25/189

Plolocl

HGGtorlcHrillululc

Science nd ditferent

ses

or

he

device:

o

You

anmake everalexperiments

nanimalconditioning,ncluding

the

ones

hat ive n the water. ry

o

alter

he RC network

P1,

R1 and

Cl) to

get

onesof ditferent

itch.

ry o usediodes, mall ransformer

coils

and other

passive

omponentsn this

experiment.

ounds

ike

those

produced

ysongbirds anbe

generated

ith

a

few

components

arranged n the

correct

way.

Can

you

discover

how

o do

it?

o

Removehe

piezoelectric

ransducer

nd

wire

electrodes

n ts

place.

The

device an be useas a nervstimulator. xperiments

ithanimals

and

plants

can be made.What

physiological

unctions

re atfected?

Can

circadian hytms

r

internal

iological

locksbe atfected y con-

tinuousexposureo sounds?

o

Electrodes

laced

ntowater

and wired n

place

of the transducer

will

produce

current ield.You an

pedorm

nteresting

cientific

ork

relating ow ish

andother

Water

eings eact o the

current

ield.

Can

the current ieldsaffect

physiological

unctions?f

you

experiment

ith

plants,

elect

a

fast

growing

ouse

plant.

80


26/189

ftn

rdccEhr[tcHnilmms

FREE-POWER

M

RECEIVER

RE)

Thisprojectusesa strangeway o get ts power.t usespower extracted

from

he uned

tation

o

give

o

the amplifier

ransistor.

itha

reasonably

strong

pplied

modulation

nvelope,

his

ypeof detector

roduces

strong

demodulated

utput.

Naturally,

he

closer

ou

are

o a strong

tation,

he

more urrent

our

adio

willbe

able

o supply.

For

best

esults,

ou

must

oeverything

ossible

o deliver

strong

ignalto

the ransistoretector. erecommendgoodantennandground,he at-

ter

preferably

eing

madeo a

water

ipe

or solid

xternal

round

omposed

of a

pipe

driven

t

east

feet

ntomoist

arth.

his

s mportant

orensuring

maximum

ignal

ickup.

I

lf

you

have

lenty

f space

vailable,

he

ongerheantenna

up

o about

00

feet),

hebetter

he

results.

Figure

shows

he schematic

iagram

f the

Free-Power

M

receiver.

b-

servehat heheartof thecircuitsa germaniumransistorhatworks sa

detector

ndaudio

mplifier.

Gomponents

lacement

n a

terminal

tripused

as

a chassis

s shown

n

Figurc

2.The erminal

trip

anbe

ixed nanexperiment

oard

hatcanbe

constructed

sing

ome ommon

ools

and

materials.

Ql

isany

germanium

ransistor,

uch

s

GE-2 r

2N107.You

an

ind

germa-

nium ransistors

n

old

nonworking

M ransistor

adio

eceivers.

onworking

AM radios analsosupplyhevariable apacitornd he oopstickferrite

rod).

Earphone

ust e

a

high-impedance

rystaltype.

ow-impedance

arphones

don't

unction

n hiscircuit.

_


27/189

Pnffi

r Foailrmlilrsrffi

Figure

I

s - 4 ^ o

Figurc

2

t8


28/189

frn?nfffihrucmlffi

--

Parts

List

-

Free-Power

M

Receiver

Q1

-

NPN

or

PNP

germanium

ransistor

see

ext

XTAL- Crystal arPhone

L1

-

LooPstick

see

ext

CV

-

365

pF

variable

apacitor

see

ext

Rl

-

12,000

hm,

114W,57

esistor

C1

-

1 uF,

25

WVDC

lectrolytic

apacitor

ldeas

o

ExPlore

To

earn

more

bout

hecircuit:

o

Replace

l by

15

urns

of

No.

28

wire,

wound

n

a

ferrite

od,

o

tune

short'wave

tations.

o By eplacing l withagermaniumiode nd emoving1andC1

you'litransform

his

adio

nto

a simple

rystal

et'

o

Alter

R1

n a

range

etween

,7}Oand

7,000

hms

o

get

better

performance,epending

n

he

ransistor

sed'

o

Replace

he

ransistor

itha

silicon

ype,

uch

s

he

8C548'

What

will

haPPen

ithsensivitY?

science rojectnvolvinghecircuit nd,uncommonses:

o

Explain

ow

rystal

ets

unction

nd

ellabout

adio

istory.

f

you

are

nterested

n

more

adio

istory

everal

exts

an

be

ound

n

the

public

ibrarY.

o

lf

you

want

o

earn

more

bout

adio

eceivers,

ry

o

ind

nforma

tion

about

eterodyne

nd

super-hereterodyne

ypes'

-

tl


29/189

HEFfdffiffnrffilmrbl

DUAL-LED

LASHER

E,P)

Thiscircuit

sesa

one-gate

scillator,

itha

4093

CMOS

G,

o

produce

50%

duty-cycle

lasher

n two

LEDsor a bi-color

ED. he circuit

an

be

poweredya 3 to 12-voltower upply nd s usefulnseveral xperiments

and

practical

pplications.You

anuse

t as

part

of alarms,

arning ystems,

games,

oys, ndsome

cientific

xperiments,

s

wewilldescribe

ere'

R2and

R3

values epend

pon

he

power

upply

oltage, ccording

o the

following

able:

Power Supply

3 Volts

5

Volts

6

Volts

9

Volts

12

Volts

R2, R3

220ohms

330 ohms

470 ohms

820

ohms

1,000 hms

Formore utput oucanusea transistorizedutput tage rivingncandes-

cent

amps.

Experiments

o observe

ightetfects n animals

nd

plants

an

beconducted

ith hiscircuit.

Pl andC1

determine

lash ate.

Flash

ate

can

be adiusted

y

P1,butCl

also

canbe

altered

n a

large ange f

values,

ccording

o theapplication

you

ntend

or hedevice.

Schematic

iagram

or he

Dual-Led

lasher

s

shown

n Figure

1.

One

gate

of a 4093C s usedasoscillatornd heotherwoareusedas nverters.

Components

lacement

n a

PCboard

s

shown

n

Figure2.You

analso

usea

breadboard

r solderless

oard

o mount

t

as an

experimental

ircuit.

Positionf

he

polarized

ieces,

uchas

LEDs, letrolytics

nd

C,should

e

observed.

tf


30/189

,,

trmAl

ld.|nm*ol

P1

R1

tM

100K

cl

1pF

(.)

SEE

TEXT

- - - t ,

z ' i

I

, l

- . \-,

\-_

LEDl

Figure

1

t{

+ 3 a

12V

ov

c1

3 E

n D r

Figure

2

ft


31/189

Iun

Plolects

ol thc

Dttrcfimcntot

Parts

List

Dual-Led

lasher

lC1

-

40938CMOS

ntegrated

ircuit

LED1

-

bi-color

r

red

and

green

ommon

EDs

(RadioShack276-012l

R1

-

100,000

hm,

114W,5%

esistor

R2,3

-

resistor ccording

o

power

supply

oltage see

ext

P1

-

1,000,000 hm

potentiometer

C1

-

1

uF,

25

WVDCelectrolytic

apacitor

ldeas

o Explore

To

earn

moreabout

he circuit

nd

devices:

o

ReplaceC1

with capacitors

n the

rangebetween

1 and

47 uF.

Observe owhigher aluesalter heflash ate.

o

Infrared

EDs an

be used

n

some

experiments.

ochange

n he

original

ircuit

s necessary.

Science

nd

different

ses

or he

circuit:

o

Remove

P1 and

R1 and

wireat this

pont

a

touch

sensor

r elec-

trodes.

oucan

control

he

flash

ateby

touch.

A

bio-feedback

evice

canbe made hiswaY.

o

By wiring

he

lC s

pin

1 to an

external

ircuit,

he

flasher

an be

controlled

y a

logic

evel.CMOS

circuits

an

be used

o control

he

flasher.

il


32/189

,

,

Pnml

mu+nnm

o

Mount

he

LEDs

n

place

f he

enses

,

.ffi

flash

ate

an

be

adjusted

o make

n

hypnotic

r

relaxingLtfect.

om

bine

his

with

a

touch

ensor

nd

you

have

n

uncommon

io-fee

back

evice.You

an

also

use

his

circuit

o make

xperiments

n

circa

dian hythms r internal iologicallocks, eterminingow heycan

be

altered

y ight

pulses.

arious

heories

ave

een

proposed

bou

this

subject.

.

Psychiatrists

re

using

phototherapy

o help

some

patients.

an

you

ind

some

application

or

he

circuitn

his

ield?

.

Pl

also

an

bereplaced

y

resistive

ransducers,

uch

as LDRs

r

NTCs,

o

give

a light-

r emperature-dependent

lash-rate

ircuit.

x

periments

anbe madewithconductivityf materialsyconnectin

probes

n

series

with

R1.

Replace

l

with

he

probes

n

his

case.

g l


33/189

IunProfcctsorstGrDcIlmGntGl

6V

X 1A POWER

UPPLY

P)

Inorder operform xperimentsndprojectsnvolving lectricityouwillneed

a sourceof

voltage. oltage equirements

or

common

projects,

uchas the

ones

n

hisbook, epend

pon heirapplications,

nd

typicallyange rom

a

few milliamperes

o one or two amperes.

lnstead

f usinga battery

ou

can usea circuit alleda

power

supply.

The

power

supply

we

show

here

can be used o

provide

V

x 1A regulated

output

o

the experimentalnd

practical

ircuitsdescribedn this

book.

The

outputvoltage s fixedby the lC.

Figure

shows he schematic

iagram

or

his

power

upply.Ol is a voltage

regufator,7806.

The

"06"

indicates

hat

t is

a

6-volt

egulator.

Figure2

shows

he

componentsayout, sing

a

terminal

tripas chassis.

The

complete

roject

an be assembled

n

a small

plastic

ox.

The ntegrated

circuit hould e

mounted

n a heatsink. ou

canalsoaddan LED n series

witha 470ohm resistor, ired n theoutputof the circuit o indicatehat t is

on.

External ircuits

an be connectedo the

power

supply

with

alligator lips.

Position f the

polarized ieces,

uch

as diodes,

he lC,

and electrolytica-

pacitors,

must

be observed.

The ransformersn't

a critical

art

of

this

project.

ypes

with

a

secondary

oil

rangingrom

7.5 to 12 volts

and currents etween

00

mA

and

14

can be

used.

5f


34/189

trolrct

g

8u

ll

Pil0tsuillr

D2

1N4002

c2

100pF

tl_

T

I

I

=

T1

12

+

'l2Y

1 A

lou

c1

1000pF

Figure

I

Fiaure

2

t

55


35/189

mFrtmctrtrtrHilffi

PartsList

-

6-Volt

Power

Supply

lOl

-

7806

positive

hree-terminalegulator

T1

-

Transformer:

rimary

17VAC

seconda

y

12+12Y 1A

D1,2

-

50V

x 1A 1N4002

r

equivalentilicon

ectifier

iodes

C1

-

1,000

F,25WVDC

lectrolytic

apacitor

C2

-

10

uF,

12WVDC

lectrolytic

apacitor

S1

-

SPST witch

ldeas

o Explore

To

earn

moreabout he

circuit r alter he

performance:

o

ReplaceC1

bya 7805, 809

or

7812

f

you

want

a 5V 9Vor 12V

power

supply. oumayalsohave o change he transformer itha

117:15+1

Vusing 7812.

.

Explain ow

he

circuit

works.

o

What s the

ditference etween

n AC

and

a DC

current?

Science nduncommon

pplications:

o

This

power

upply an

be used

n

chemical

xperiments,uch

as

theones hat nvolve urrentlow hrough ubstances.xperiments

involving

lectrolysis

ndelectroplating

re wo hat

canbesuggested.

A variable ound-wire

otentiometer

100

ohms, watts) hould e

wiredn

series ith he

power

upply utputo imit

urrentlow hrough

the

oad.You

an

alsouse heLightDimmer

escribedn his

book

or

this ask.

a


36/189

Plrflct

g

0u

r

lt Pilil $utilr

o

6V

200

mA small

ncandescent

amps an be supported

y

this

power

upply.

hese

amps re excellent

ightsources

o

work

with

microscopes.

o

Small

motors

nd

ampsnexperiments

nvolving

hysics,

echan-

icsand oboticsanbepoweredrom hispower upplywithadvan-

tages.

ou

don't

have o spend

lot

of

money n

cellsor

batteries.

o

All

circuits

escribed

n hisbook

which

equire 6V

supply

anbe

powered

y

his

power

upply.

o

Thecircuit

anbe

usedas an

excellent

ower

dapter

or

youi

6V

equipment,

uch

as small

adios,

alculators,

tc.

o 6V amps anbe usedn experimentsnvolvinglantgrowth. e-

lecta

fast

growing

ouse

lant

nd

use.a arkroom

r

cardboard

ox

to coverthem.

amps

ith

olored

ilters an

beused

nanexperimen

involving

rowth

nd

development.

o

Circadian

hythms an

also

be studied

singanimals

r

plants.

Lamps an

be

powered

n

at

night

nd

otfat

day.

What

physiologica

functions

ould

beatfected?

5t


37/189

mFilncNsfffirHrufinrm

rNsEcT

REPELLENTP)

Some ontinuousoundsan epelnsectsandalsoattract).he requency

and ntensity

epends

pon he

application

nd ype

of insect

nd

can be

found

hrough

xperimentation.

The

circuit

hown ere

generates

continuous

ound

hat

canbe

used o

repel

or

attract)

ome

ypes

f

nsects,

r n

scientific

xperiments

nvolving

animals.

Our nsect

epellent

an

be

powered

y9V

batteries,wo

M

cellsor our

AA

cells,and ts owcurrent equirementsillextendhe ifeof those ellsor

batteries.

Figure

showshe

schematic

iagram

f

the nsect

Repellent.

heheart

f

thecircuits

a 7555 C,

a

CMOS

imerwired

s

anaudio

scillator

nddriving

a

piezoelectric

ransducer.

The

components

lacement

na homemade

rinted-circuit

oards

shownn

Figure

2.

Exact

placement

s not

hat

critical.

All he

components

nd he

power

upply an

behoused

n

a small

lastic

ox.

Transducer

Z

s

a crystal

arpiece

ra

piezoelectric

ransducer,

uch s he

Radio

hack 73-073.

Position

f the

polarized

ieces,

uch

as

c2 and he

power

upply,must

be

carefully

bserved.

Using he nsect

epellent

s very

easy. ou

onlyneed

o

adjusthe

rimmer

potentiometer

1 o

produce

soundwith hesamepitchas the nsect ouintend

o

repel.

xperimentation

hould

emade

ntilyouind

he

best ound

to repel

specificnsect.

60


38/189

E

led

l0

In$octidhm

R2

4K7

cl0.047p.F

Figure

1

Figure

2

01


39/189

ftrF||f|Gilthlhsuh |m

Parts

List

-

Insect

Repellent

c1

BZ

R1

R2

P1

c1

c2

S1

B1

-

TLC7555

MOSntegrated-circuit

imer

-

Crystal

r

piezoelectric

ransducer

RadioShack 73-073r equivalent

-

10,000

hm,114W,5%

esistor

-

4,700

hm,114W,5%

esistor

-

100,000

hm rimmer

otentiometer

-

0.047

F metal

ilm

or

ceramic

apacitor

- 10uF,12WVDC lectrolyticapacitor

-

SPST lide

or dggle

witch

-

3V

(2

AA

cells),

V

(4

M

cells),

V

(battery)

ldeas

o Explore

To

earn

more

about

he

circuit

r

get

better

erformance:

.

Powerful

utput

anbe

obtained

ith

a transistorized

utput

tage

as shown

n Figure

3.

The

power

ransistor

hould

e mounted

n

a

heatsink.The

ransducer

s

a ow-impedance

oudspeaker

:anging

rom

4

to

8 ohms.

o

Experiments

ith

ultrasound

ah

be made

with

his

circuit:educe

Cl to 1200

F

anduse

a

piezoelectric

weeters ransducer.emovethesmall

ransformer

sed

n hese

weeters

nd

plug

he

ransduce

directly

o the

circuit

utput.

utputsn

requencies

s high

as40,000

Hz

can

be

produced

y his

circuit.

o

Explain

ow

sounds

an

be

produced

y

electronic

ransducer

suchas

he

oneused n

his

project.


40/189

?nhd

l0 InrstirDdhnt

o

Whatareultrasounds?

Science

ndditferent

pplications:

a

Of

course,

ou

can est

he realetfects f

this deviceon

several

kinds f nsects. n attractiveiologicalxperimentanbeconducted

based n

hiscircuit.

o

Etfects f sounds n

plantgrowth

r development

an be

con-

ducted sing

hiscircuit.Can

sounds

qr

ultrasounds)

lter hecirca-

dian

hythms f

plants

nd

nsects?

o

The

continuous

one

produced

y

hiscircuit anbe

used

n

alarms

or

warning ystems.

ice

and

other mallanimals

re

repelled y

powerfulltrasounds.

o

Replace

2byan

LDR.Theircuit

ow

becomes

light-dependen

oscillator.

xperiments

ith ightandsounds an

nowbe conducted

using

hedevice.

6 to 12V

Figure 3

08


41/189

HnPnlmts||]mHlo|lmeml

ULTRASONIC

ENERATOR

E/P)

Dogs,

mice, ats

and

other

nimals

an

hear ounds

ith

requencies

p

o

4O,O0O

z.

There re

several

inds f

insects

hat

canalso

hearor

react

o

thesesounds. he circuitwe propose ereproduces continuousound

emission

n frequencies

bove

he

human

imit,or a

range etween

8,000

and

40,000

Hz.

These ounds

re

called

ultrasounds

nd

can

be used

n

several

xperimental

nd

practical

pplications.

The

device

edescribe

ere

anbe

used

o scare

ogs nd

other

nimals,

n

biological

xperiments,

nd

many ther

nterestingpplications.

The

recommended

iezoelectric

ransducer

as

ts maximum

utput

owe

between 00 and 3,000Hz, but t alsowill operate t higherrequencie

emitting

ess

power.

The

ecommended

ower

upply

s ourM cells

or a

9-volt

attery.

Our

project

unsbetween

pproximately

8,000

nd

40,000

Hz,but

you

can

easily

lter

his

ange ychanging

1,

n a

range etween

70

pF

and0.001

uF.

Frequency

anbe

setby

P1

n he

range etermined

y C1.

Rememberhat he40938C willoscillaten requenciesp o 500kHz.

The

complete

ircuit

f

the Ultrasonic

enerator,

sing

he

our

gates

of a

40938

ntegrated

ircuit,

s shown

n Figute

1.

Components

lacement

n a

printed-circuit

oard

s shown

n Figurc

2.

Thecircuit

an

be

housed

n a small

plastic

ox

and

he ransducer

illbe

fixed

n he

ront

panel.

Take are

with he

position f thepolarizedarts, uchas thetransisto

electrolytic

apacitor

nd

power

upply.

Forcontinuous

peration, 1

should

e

mounted

n a

heatsink'

The ransformer

s nota critical

art.

Any ransformer

itha

secondary

oil

ranging

rom

100 o 500

mAcan

be

used

n his

project.

-

00


42/189

F.lect l

uftmmlcecmntu

Figure I

Figure 2

0t


43/189

HiFrrN.Gt3ffimmdlmrfit]

PartsList

-

Ultrasonic

Generator

lC1

-

40938

CMOS

ntegratedircuit

Ql

-

8D135medium-powerPN iliconransistor

BZ

-

Piezoelectricransducer

RadioShack

73-090

r

equivalent

Tl

-

Transformer:

rimary

17VAC;

econdaryVx100

mA

R1

-

10,000

hm,

114W,5%

esistor

R2

-

1,000

hm,

114W,5%esistor

Pl - 100,000hm rimmerotentiometer

C1

-

4,700

F

ceramic r

metalilmcapacitor

C2

-

100

uF,

12 M/DC

electrolyticapacitor

S1

-

SPSToggle r slide witch

81

-

6V

or 9V

-

AA

cellsor battery see

ext

ldeas o Explore

To earnmoreabouthecircuit r

o

get

better

erformance:

o

You

an

eplacehe

piezoelectric

ransducerya common

weeter.

Remove

1

and

BZ

and

place

he weeter

etween 1

and

Ql's

col-

lector.Can

you

measurehe

generated

ltrasound

ower?

.

Thecircuit analso

generate

ound

n

heaudible

ange. eplace

Cl bya

capacitor

n

he

ange

etween .02and0.1uF.

o

Explain ltrasoundsnd

how hey

re

produced

yelectronic

rans-

ducers.

0l


44/189

P'rhct tt

Uhffuh8emn0r

o

What s

a

piezoelectric

aterial?

Science ndditferent

pplications:

o

Several xperiments

anbe made

sing ltrasounds.

ou

anex-

periment ithdogconditioning.singhisoscillatoroucancalla dog

using n

naudible

ound

inaudible

o humans)

o

Ghoose capacitor

etween

.01and

0.047 F o

produce

ounds

both n

the audio ange

nd

ultrasoundange. ou

an

now

conduct

experimentso

determinehe

exactupper-limit

requency eard

by

humans.You

lso anconduct

xperimentsith

animals.

t

willbe m-

portant

o have frequency

ounter n hand

o do hiswork.

o Replace Zbyelectrodes.hecircuitwillgenerate high-voltage

outputhatcan

beused

n

nerve

timulation.

se

a 10,000

hm

poten-

tiometer

o

adjust utput oltage

t his

point.

ulses

an

each

eaks

as high

as

400

volts.

o

To

get pulses

for

nerve

timulation

nd otherexperiments)

ou

onlyhaveo replace

1with

a

1

uFcapacitor

ndP1with

a

1,000,000

ohm

potentiometer.

ulses

n he rate

ange

etween

.1

per

second

to 10

per

second anbe

generated

ith his

change.

o

This

ircuit analso

beused s

a

fluorescent

ampnverter.

com-

mon luorescent

amp

4

to 20 wafts) n

place

of the ransducer ill

glow,

ven

one hat

s

weak

enougho not unction

n

heAC

power

line.

00


45/189

Hr PnhG[slorl[c

ilmmt

DC

LAMP

DIMMER

E,P)

Thiscircuit

an

be

used

o controlthe

mount

f

current

n an

ncandescent

lamp

andalso

a

DC

motor.

f

you

change

heamount

f

current

hrough

lampyouchangets brightness.nd f youchangehe amount f current

through

DC

motor

ou

change

tsspeed.

nput

oltage

an

ange

rom

6 to

12

voltsand

current

rain

n the

output

s

up

to

2A.

Youcan

also

use

his

circuit

n the output

f

a 6V

or

12V

ixed

power

upply,

onverting

t intoa

variable

to 6

voltor

0

to

12voltsupply.

The

power

ransistor

hould

e

mounted

n

a

heatsink.

hecircuit

an

be

housed

n

a

small

lastic

ox

and

he

heatsink

ith

he ransistor

ixed

n

the

outside.

Thecircuit

an

be used

o control

rightness

f

a car's

panel

amps nd

n

robotics

o control

DC

motor peed

long

wide

ange

f

values.

lso,

ev-

eral

experiments

nvolving

urrent

low

control

an

be

performed

sing

his

circuit.

Thecircuit

cts

as

a

variable

esistor

r

rheostat

ith he

principal

urrent

flowing

hrough

he

ransistor

nd

he

control urrent

lowing

hrough

he

po-

tentiometer.

urrent

hrough

he

potentiometer

s onlya

few

milliamperes.

The

schematic

iagram

f

the

DC dimmer

s shown

n Figurc

t.

Ql

is an

NPN

power

ransistor

nd

he

principal

omponent

sed

n this

project.

Components

ayout

s shown

n Figure

2.

Thetransistor

oes

not show

on

the

heatsink,

owever.

Equivalent

ransistors

an

be used,

ut

akecare

with

he

maximum

urrent

they

can control.

ypes uch

as

TlP31and

TlP41

can be

used

o control

lampsup to 2 amperes. lso,a furthermodificationn Rl valuemustbe

made

o

ensure

hat,

when

P1

s set

near

ts minimum

alue,

hatcurrent

s

flowing

hrough

he

amP.

lf

equivalent

ransistors

re

used,

ake

care

with

heir

erminal

ositions,

s

theycan

be

ditferent.

-

AD


46/189

Prrfoct

2 DG

mr Iilmmu

Figure

I

F1

5A

Q1

2N3055

+12V

IN

oul

I

:

Figure

2

t3


47/189

Hr]||Fc0tffimDculmffir

PartsList

-

DCLampDimmer

Q1

P1

R1

F1

-

2N3055 Silicon

NPN

power

ransistor

- 4,700ohmpotentiometer

-

470

ohm,

2W,.5 /

esistor

-

5A

fuse

ldeas o Explore

To earnmore bout

hecircuit r

to

get

better

erformance:

o

Youcanusea

PNP

power

ransistor,

nvertingnput

polarization

Explain

hy hiscircuit anonly

controlDCcurrents.

o

A Darlington

ransistoranbeused

o reduce urrent

low hrough

the

potentiometer.

eplace 1witha 100,000 hm

common

otenti-

ometer

nd Rl

with

a

10,000 hm,

1/4watt esistor

hen

using

a

Darlington

ower

ransistor.

lPl10canbe used

n hiscase.

o

What s a rheostat?

Science

nduncommonpplications:

o

Youcan use

his

circuit

o control rightness

f microscope

ight

sources. 6V

ampcanbe used

or hat ask

and

hiscircuit

willbe

wired

between

he

amp

and

a 6V

power

upply.

he 6V

regulated

power

upply escribed

n his

book

s deal

or his

application.

o

Experiments

n

electrolysisnd

electroplatinganbe

current-flow

controlledy using

hiscircuit.

a

Thiscircuit anbe used o

control mall

motorsn robotics r

in

physics

xperiments.

tl


48/189

ffi|m n

mllmDllmmei

o

The

amountof current

n

current ieldscan

be controlled y using

this

circuitand a

DC

power

supply.Experimentsnvolving

lectrotro-

pism

can be attempted. ry o

put plants

within

a coil

o

observe

he

influence

f

the magneticield

on their

growth

and

development.

e-

member

hat there

s

a magnetic ield

arounda coil of

wire

that

is

carrying current.

Figure3

showshow his experiment

an be arranged.

The

coil

s formed

by 10 to

50

turns

of common

No.1

to 22wirearounda

cardboard oxor wood orm.An

ammeter

n

series

with

he coilcircuit anbe

used o control he amount

of currentused

n

the experiment.

Remember

hat too much

current

will

cause he coil and the transistoro

overheat.t is a good dea o add a lamp n serieswith he coil circuit. he

lampwill

add resistanceo the coil

circuit,

educing

urrent

low

to a safe

level.

Figure

3

t5


49/189

Iun

Piilcctsfuh

scilmmu

AUDrOOSCILLATOR

E)

This ow-powerxperimental

scillatoran

generate

udible

ignals

n

the

range etween

00and

2,000Hz,driving

small

oudspeakerr

a low-im-

pedance

arphone.

hecircuit an

be

powered

y2 twoor

our

AA

cells

or a

fixed6

volt

power

upply.

urrent

equirements

or hiscircuit

epend

pon

the

power

upply

oltage nd he

oudspeaker

mpedancend

range ypi-

cally

rom

10

o 300

mA.

Potentiometer

1 adjusts

he operating

requencynd

can be set

within

large ange f values. otentiometersp o 1,000,000hmscanbe used,

changing

he requency

ange

owerimit

o

about

10

Hz.

C1

can

alsobealtered,

nd

values etween.01

andO.22uF

resuitable

or

experimentation.

argeC1

values

ill

produce

requencies

n he ower

art

of

he

ange.

Thecircuit an

be usedas

part

of alarms,

ames,

oysand o

learn

more

about

ransistorized

scillators.

Figure

shows

heschematic

iagram

f theAudio-Oscillator.1

and

Q2

forma directed-coupled

mplifiernd

Rl/Cl is heclosed

oop hat

akeshe

signal ack

rom heoutput

o the

nput.

.

,

Figure2shows

he

ayout

f

hecomponents,

sing

terminal tripas

chas-

sis.

All hecomponents

nd

power

upply

anbe

housedn a small

plastic

box.

Thekeysatelegraph

omemade-typewitch,

utyou an

alsousean

SPST

toggle r

slide witch

orcontinuous

peration.

key

s recommended

f

you

want o use

heoscillator

sa

Morse

Code

ender

n demonstrations

r

prac-

tice.

Youcan

wire he

points

A and

B to the contacts f

a relay

o use he

circuit s

part

of an alarm.

tt


50/189

Pf.lcct 8 ftllrosoilrt|l

cl

0.047pF

B1

3TO 6V

Figure

I

k-\

Figure2

t0


51/189

mFmf0cilsffmHrulmdu

PartsList

-

Audio

Oscillator

Q1

-

8C548

eneral urpose

PN

ransistor

Q2

-

8C558 eneral

urpose

NP ransistor

SPKR 4

or 8 ohmsmall

oudspeaker

K

-

Telegraphic

ey

See ext

81

-

3

to

6

volts two

or ourAA

cells

Ri

-

10,000 hm,114w,5 esistor

R2 - 1,000 hm,114W,5 esistor

Cl

-

0.047 F

metalilm

or ceramic

apacitor

ldeas o Explore

To earnmore

bout hecircuit r o

get

better

erformance:

o

Change

1

or

a capacitor

n

he ange

etween

.01

and

0.22uF.

The

requencyange

f the

produced

one

will

be

altered.

With

0.01

uF

or

lower aluesor

Cl,

thecircuitwill

produce

ltrasounds.sea

tweeter

r a

piezoelectric

ransducer

n his

case.

.

Replace

1

with

a

TlP32

orTlP42

nd

poqer

hecircuitwith

a

12

volt

supply.You'll

et

muchmore

power

n he

output.

.

Explainwhy

oscillators eeda closedoop o thesignalo work.

Science

rojects

ndother pplications:

o

Experimentsn

acoustics

anbe

made

with his

device.

he

circuit

can

produce

ny one

between

0

and20,000Hz,

andeven igher.

tt


52/189

;nlrcr l3

|latr

Iscffia.]

o

A telegraph

tation

anbe simulated ith

his

circuit.

ou

an

ind

Morse

Code

n

anybook

about elegraphy.

o

By eplacing with

a reed

wichwiredo

points

and

B, he

circuit

willoperates an alarm.

o

Experiments

nvolving

onductivity

f

materials

anbe

made

with

probes

lugged

o

points

and

B.

o

Connectesistive

ransducers

s LDRs ndNTCs

t

points

and

B to

get

a

light-dependent

r emperature-dependent

scillator.

a

Using

wo metal

ods

as sensors,he

circuit an

be useas a

lie

detector r bio-feedback

evice. eplace

l

with

a 0.22or 0.47

uF

capacitorndadjustPl to getseparatedulses

t the

speaker.

he

pulse

atewill

bealtered hen he

skin

onductivityf he nterrogated

person

hanges

hile

n

a stateof strain

ue o a lieor

stress.

o

A 117V+V x 250mA

ransformer

an eplace

PKR o

produce

high-voltage

ulses

n nerve

timulation

xperiments.

he

generated

pulses

an

each

oltages

s

high

as 400Vpp.

o

Experimentsn

animal

hysiology

an

beconducted

sing ounds

or highvoltage s describednotherprojects. rowth f plants ub-

mitted

o high-power

ounds

r

high-voltage

ields

an be observed

using

hiscircuitwith

practical

xperiments.

o

AC ields

anbe

generated

y

eplacing

he

speaker itha 2O-turn

coil.

The

plants

r animals

anbe

positioned

ithin

hecoil's

lectric

field.

See hesame

experiment

singheDCDimmeror

coiland

ex-

periment

etails.

tl


53/189

IunPnfmtrfimH|Oilmmr

AUDIO

SWTTCH

E/P)

Thisaudio ontrolledelay asa large umber f applicationsnd

s nterest-

ing o he

experimenter

howisheso

explore

heworking

niversef

relays

andaudio r sound ontrolledircuits.

An

audio

ignaln he

amplitude

ange etween Vppand

5

Vpp riggershe

relay,

owering

n

he

device,

ired

etween

oints

and

B.

Relay alues determinedy

power

upply oltage. ora 12volt

power

up-

plyyou

must

usea

12volt elay.

urrent

rain

epends

pon he

power

up-

ply

voltage

ndalso he

elay

sed.Using 12Y

x

38

mA

Radio

hack

75-

248'1relay,hecurrent rains owenougho allowheuseof commonells

n

thepower upply.

Cl

can

ange

etween.01and1.0uF,anddetermineshesensitivityf

he

circuit

n he

audio

ange. arge alues

ive

more

ensitivity

t ow

requen-

cies.

Thiscircuit

as

a

high-impedancenput

and

needs

strong udio ignal

o

operate.

Figure showsheschematiciagram f heAudioSwitch. bservehat he

heart f hecircuits a common

eneral-purpose

PN ransistorhatactsas

a

DCamplifier.

ln

Figure

2we show

ayout

f components

or

his

project.

he

components

canbesolderedna terminaltripused schassis.Theerminaltrip anbe

flxed n a wooden oard.

Positionf the

polarized

omponents,uchas hediodes,

ower

upply nd

capacitor 2,mustbeobserved.

To

use hisaudio

elay

ou

have

o

wire

ponts

A

and

B

to the output

f an

audioamplifier

minimum

ower

equireds

5

watts) ndadjusthe

volume

control

or

bestoperation.

A

small

ransistor

utput

ransformer

hould eused

o

operate

he elay

with

low-impedanceignals,uchas heones

rom

heoutput f audio mplifiers.


54/189

Fofeot f

lullr ilftGn

D2

1 N 9 1 4

D1

R1

1N914

, t0K

(.)

sEE

TEXT

B1

6 O R 9 V

Figure I

Figure 2

05


55/189

mrilffi||rrhsll|mmr

Figure

3

shows

how

o use his ransformer.

R,depends n

he

output

ower

f

the

amplifiernd

s

given

elow:

Output

Power

0

to 1 watt

1

to

10watts

10

o 25

watts

25to50watts

I

47

ohms,

1/4watt

100

ohms,' l l4watI

220ohms,ll2watt

PartsList

-

Audio

Switch

Q1

-

8C548

general-purpose

PNsilicon ransistor

D1

-

1N914

eneral-purpose

ilicon iode

D2

-

1N4002

ilicon

ectifier iode

Kl

-

6V

or 12V

relay

see ext

R1

-

10,000

hm,

1/4W,5% esistor

Cl

-

metal ilm

or ceramic

apacitor

see

ext

C2

-

100 uF,12WVDCelectrolytic

apacitor

81

-

6V or

12V

cells,

power

supplyor battery

t0


56/189

;TrM

lf rilm nilH

ldeas

o Explore

To earn

more

about hecircuit

nd

devices

r o

get

better

erformance:

o

Replace

l

with

a

Darlington

ransistor

such

as a BCS17)ndresistor

1 with100,000

hms. he

circuitwill ncrease

n

sensitivity.

o

Explain

ow

C1 unctionsn

his

circuit.

Science nd

different

pplications:

o

Connecthe

circuito

anaudio mplifier

utput, ith

a mioophone

plugged

o the

amplifiernput.You'll

ave

sound-operated

witch.

o Thiscircuitwitha microphonendanaudio mplifieranbeused

to close

a trap with

sound

activation

r

to

activate recording

ith

sounds.

You

can alsouse t

to

photograph

n

explosion

r the crash

of an

object

y riggering flash

with

he

produced

ound.

o

The

audio

output f

a

multimedia

ystemn

a computeran

be

used o

control

xternal evices ith

his

circuit.

R;

l-----+x

FRoM

IIF

ro

AMPLTFTER

3lE

AUDlos\

ourPUT

|

' ' l

L._--_-{'Y

8 :

1000

o

Figure

3

tt


57/189

IunPnlos lol UrG nilmomcr

6

VOLTSFROM12V

BATTERTES

P)

With hisadapter oucanpower6 volt up o 1A)devices, uchas recorders,

CD

players,

alculators,adios, attery

hargers, tc., rom

your

car battery.

The

currentadapter s

plugged

nto the vehicle ighter

socketand is small

enough

o

be

housed n

a verycompact

lastic

box.

Only

our

components

re used.

The

lC determines

he outputvoltage

and

shouldbe mounted

n a

heatsink.

apacitors re

polarized

omponents,o

you

must

observeheir

position

whenmounting.The

use s very mportant

n

order o

protect

he

deviceand car wiring

against horts.

Output ariesaccordingo the

device

ou

are

applying

ower

o. DC

exten-

sioncableswith

plugs

o fit the

device o be

powered

houldbe used.Take

care with the

output

poles.

Check

f

your

devicehas a

positive

r

negative

pole

n the

centralerminal.

The

schematic iagram

f the

12V

o

6V

x 1A

converter

s

shown n Figure 1.

The

principal

omponent

s lC1,

a

6V

voltage egulator

hat

operates

with

input

voltages angingrom

to

35

volts.

Componentsayout s

shown

n

Figure 2. All

he components

an easilybe

housed

n a

plastic

box.

The ntegrated

ircuit an be changedo alter he

output oltage.Youan use

a

7809

or

9V

x 1A

output r a

7805

or

5V

x 1A

output.

It is very mportant

hat no

parts

of the components

sed

n

thiscircuit ouch

one another. he lC has

short-circuit

nd

hermal

protection.

t


58/189

?nhcr 5

olrilsFmlzummilis

Figure 1

Figure2

gl


59/189

m?nmffimsu||nomcr

Parts

List

-

6 VoltsFrom

12V

Batteries

lC1

-

7806

ntegrated

ircuit

C1

-

1,000

uF,16WVDC

electrolytic

apacitor

C2

-

100

uF,12

WVDC

electrolytic

apacitor

Fl

-

2A fuse

ldeas

o Explore

To earnmore bouthedevice r ogetbetter erformance:

o

Replace

he ntegrated

ircuit

lOl)

with

a

7805

or 7809 o

get

out-

put

voltages

f 5V and

9V.

o

Explain

heditference

etweenhis inear

oltage

egulator

nda

switch-modeegulator

sed n

computer

ower

upplies.

o

This

ircuit an

alsobe

used

n nonregulated

ower

upplieso

get

a regulatedVx 1Aoutput.

o

lt's

possible

o

get

a nega

fun electronics projects for the experimenter (1)

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