<s>
A	O
magneto	B-Algorithm
is	O
an	O
electrical	O
generator	O
that	O
uses	O
permanent	O
magnets	O
to	O
produce	O
periodic	O
pulses	O
of	O
alternating	O
current	O
.	O
</s>
<s>
Unlike	O
a	O
dynamo	B-Language
,	O
a	O
magneto	B-Algorithm
does	O
not	O
contain	O
a	O
commutator	O
to	O
produce	O
direct	O
current	O
.	O
</s>
<s>
It	O
is	O
categorized	O
as	O
a	O
form	O
of	O
alternator	B-Algorithm
,	O
although	O
it	O
is	O
usually	O
considered	O
distinct	O
from	O
most	O
other	O
alternators	B-Algorithm
,	O
which	O
use	O
field	O
coils	O
rather	O
than	O
permanent	O
magnets	O
.	O
</s>
<s>
Hand-cranked	O
magneto	B-Algorithm
generators	O
were	O
used	O
to	O
provide	O
ringing	O
current	O
in	O
telephone	O
systems	O
.	O
</s>
<s>
Magnetos	B-Algorithm
were	O
also	O
adapted	O
to	O
produce	O
pulses	O
of	O
high	O
voltage	O
in	O
the	O
ignition	O
systems	O
of	O
some	O
gasoline-powered	O
internal	O
combustion	O
engines	O
to	O
provide	O
power	O
to	O
the	O
spark	O
plugs	O
.	O
</s>
<s>
Use	O
of	O
such	O
ignition	B-Algorithm
magnetos	I-Algorithm
for	O
ignition	O
is	O
now	O
limited	O
mainly	O
to	O
engines	O
without	O
a	O
low-voltage	O
electrical	O
system	O
,	O
such	O
as	O
lawnmowers	O
and	O
chainsaws	B-Language
,	O
and	O
to	O
aircraft	O
engines	O
,	O
in	O
which	O
keeping	O
the	O
ignition	O
independent	O
of	O
the	O
rest	O
of	O
the	O
electrical	O
system	O
ensures	O
that	O
the	O
engine	O
continues	O
running	O
in	O
the	O
event	O
of	O
alternator	B-Algorithm
or	O
battery	O
failure	O
.	O
</s>
<s>
For	O
redundancy	O
,	O
virtually	O
all	O
piston	O
engine	O
aircraft	O
are	O
fitted	O
with	O
two	O
magneto	B-Algorithm
systems	O
,	O
each	O
supplying	O
power	O
to	O
one	O
of	O
two	O
spark	O
plugs	O
in	O
each	O
cylinder	O
.	O
</s>
<s>
Magnetos	B-Algorithm
were	O
used	O
for	O
specialized	O
isolated	O
power	O
systems	O
such	O
as	O
arc	O
lamp	O
systems	O
or	O
lighthouses	B-Application
,	O
for	O
which	O
their	O
simplicity	O
was	O
an	O
advantage	O
.	O
</s>
<s>
They	O
have	O
never	O
been	O
widely	O
applied	O
for	O
the	O
purposes	O
of	O
bulk	O
electricity	O
generation	O
,	O
for	O
the	O
same	O
purposes	O
or	O
to	O
the	O
same	O
extent	O
as	O
either	O
dynamos	B-Language
or	O
alternators	B-Algorithm
.	O
</s>
<s>
The	O
first	O
machines	O
to	O
produce	O
electric	O
current	O
from	O
magnetism	O
used	O
permanent	O
magnets	O
;	O
the	O
dynamo	B-Language
machine	O
,	O
which	O
used	O
an	O
electromagnet	O
to	O
produce	O
the	O
magnetic	O
field	O
,	O
was	O
developed	O
later	O
.	O
</s>
<s>
The	O
first	O
electrical	O
machine	O
used	O
for	O
an	O
industrial	O
process	O
was	O
a	O
magneto	B-Algorithm
,	O
the	O
Woolrich	O
Electrical	O
Generator	O
.	O
</s>
<s>
Electroplating	O
requires	O
DC	O
and	O
so	O
the	O
usual	O
AC	O
magneto	B-Algorithm
is	O
unworkable	O
.	O
</s>
<s>
Most	O
early	O
dynamos	B-Language
were	O
bipolar	O
and	O
so	O
their	O
output	O
varied	O
cyclically	O
as	O
the	O
armature	O
rotated	O
past	O
the	O
two	O
poles	O
.	O
</s>
<s>
To	O
achieve	O
an	O
adequate	O
output	O
power	O
,	O
magneto	B-Algorithm
generators	O
used	O
many	O
more	O
poles	O
;	O
usually	O
sixteen	O
,	O
from	O
eight	O
horseshoe	O
magnets	O
arranged	O
in	O
a	O
ring	O
.	O
</s>
<s>
Compared	O
to	O
the	O
bipolar	O
dynamo	B-Language
,	O
this	O
did	O
have	O
the	O
advantage	O
of	O
more	O
poles	O
giving	O
a	O
smoother	O
output	O
per	O
rotation	O
,	O
which	O
was	O
an	O
advantage	O
when	O
driving	O
arc	O
lamps	O
.	O
</s>
<s>
Magnetos	B-Algorithm
thus	O
established	O
a	O
small	O
niche	O
for	O
themselves	O
as	O
lighting	O
generators	O
.	O
</s>
<s>
The	O
French	O
engineer	O
Auguste	O
de	O
Méritens	O
(	O
1834	O
–	O
1898	O
)	O
developed	O
magnetos	B-Algorithm
further	O
for	O
this	O
purpose	O
.	O
</s>
<s>
These	O
windings	O
were	O
placed	O
on	O
a	O
segmented	O
iron	O
core	O
,	O
similar	O
to	O
a	O
Gramme	B-Algorithm
ring	I-Algorithm
,	O
so	O
as	O
to	O
form	O
a	O
single	O
continuous	O
hoop	O
.	O
</s>
<s>
De	O
Méritens	O
is	O
best	O
remembered	O
today	O
for	O
his	O
production	O
of	O
magneto	B-Algorithm
generators	O
specifically	O
for	O
lighthouses	B-Application
.	O
</s>
<s>
In	O
the	O
sea	O
air	O
of	O
a	O
lighthouse	B-Application
,	O
the	O
commutator	O
that	O
had	O
been	O
used	O
previously	O
with	O
dynamo	B-Language
generators	O
was	O
a	O
continual	O
source	O
of	O
trouble	O
.	O
</s>
<s>
The	O
lighthouse	B-Application
keepers	O
of	O
the	O
time	O
,	O
usually	O
semi-retired	O
sailors	O
,	O
were	O
not	O
mechanically	O
or	O
electrically	O
skilled	O
enough	O
to	O
maintain	O
these	O
more	O
complex	O
machines	O
.	O
</s>
<s>
The	O
de	O
Méritens	O
magneto	B-Algorithm
generator	O
illustrated	O
shows	O
the	O
'	O
ring	O
wound	O
 '	O
armature	O
.	O
</s>
<s>
Both	O
dynamos	B-Language
and	O
alternators	B-Algorithm
required	O
a	O
source	O
of	O
power	O
to	O
drive	O
their	O
field	O
coils	O
.	O
</s>
<s>
This	O
could	O
not	O
be	O
supplied	O
by	O
their	O
own	O
generator	O
's	O
output	O
,	O
without	O
some	O
process	O
of	O
'	O
bootstrapping	B-Application
 '	O
.	O
</s>
<s>
Henry	O
Wilde	O
,	O
an	O
electrical	O
engineer	O
from	O
Manchester	O
,	O
England	O
,	O
developed	O
a	O
combination	O
of	O
magneto	B-Algorithm
and	O
electro-magnet	O
generator	O
,	O
where	O
the	O
magneto	B-Algorithm
was	O
used	O
only	O
to	O
supply	O
the	O
field	O
to	O
the	O
larger	O
alternator	B-Algorithm
.	O
</s>
<s>
These	O
are	O
illustrated	O
in	O
Rankin	O
Kennedy	O
's	O
work	O
Electrical	O
Installations	O
Kennedy	O
himself	O
developed	O
a	O
simpler	O
version	O
of	O
this	O
,	O
intended	O
for	O
lighting	O
use	O
on	O
ships	O
,	O
where	O
a	O
dynamo	B-Language
and	O
magneto	B-Algorithm
were	O
assembled	O
on	O
the	O
same	O
shaft	O
.	O
</s>
<s>
The	O
current	O
generated	O
in	O
the	O
magneto	B-Algorithm
is	O
transmitted	O
by	O
wires	O
attached	O
to	O
the	O
rotating	O
shaft	O
to	O
the	O
dynamo	B-Language
's	O
rotating	O
field	O
coil	O
.	O
</s>
<s>
The	O
output	O
of	O
the	O
dynamo	B-Language
is	O
then	O
taken	O
from	O
the	O
stator	O
coils	O
.	O
</s>
<s>
This	O
is	O
'	O
inside-out	O
'	O
compared	O
to	O
the	O
conventional	O
dynamo	B-Language
,	O
but	O
avoids	O
the	O
need	O
for	O
brushgear	O
.	O
</s>
<s>
The	O
invention	O
of	O
the	O
self-exciting	O
field	O
by	O
Varley	O
,	O
Siemens	O
&	O
Wheatstone	O
removed	O
the	O
need	O
for	O
a	O
magneto	B-Algorithm
exciter	O
.	O
</s>
<s>
A	O
small	O
residual	O
field	O
in	O
the	O
iron	O
armature	O
of	O
the	O
field	O
coils	O
acted	O
as	O
a	O
weak	O
permanent	O
magnet	O
,	O
and	O
thus	O
a	O
magneto	B-Algorithm
.	O
</s>
<s>
The	O
shunt	B-Algorithm
wiring	I-Algorithm
of	O
the	O
generator	O
feeds	O
some	O
of	O
its	O
output	O
current	O
back	O
into	O
the	O
field	O
coils	O
,	O
which	O
in	O
turn	O
increases	O
output	O
.	O
</s>
<s>
Use	O
of	O
magnetos	B-Algorithm
here	O
is	O
now	O
obsolete	O
,	O
though	O
separate	O
exciters	O
are	O
still	O
used	O
for	O
high	O
power	O
generating	O
sets	O
,	O
as	O
they	O
permit	O
easier	O
control	O
of	O
output	O
power	O
.	O
</s>
<s>
Magnetos	B-Algorithm
have	O
advantages	O
of	O
simplicity	O
and	O
reliability	O
,	O
but	O
are	O
limited	O
in	O
size	O
owing	O
to	O
the	O
magnetic	O
flux	O
available	O
from	O
their	O
permanent	O
magnets	O
.	O
</s>
<s>
The	O
fixed	O
excitation	O
of	O
a	O
magneto	B-Algorithm
made	O
it	O
difficult	O
to	O
control	O
its	O
terminal	O
voltage	O
or	O
reactive	O
power	O
production	O
when	O
operating	O
on	O
a	O
synchronized	O
grid	O
.	O
</s>
<s>
Power	O
generation	O
magnetos	B-Algorithm
were	O
limited	O
to	O
narrow	O
fields	O
,	O
such	O
as	O
powering	O
arc	O
lamps	O
or	O
lighthouses	B-Application
,	O
where	O
their	O
particular	O
features	O
of	O
output	O
stability	O
or	O
simple	O
reliability	O
were	O
most	O
valued	O
.	O
</s>
<s>
Small	O
wind	O
turbines	O
,	O
particularly	O
self-build	O
designs	O
,	O
are	O
widely	O
adopting	O
magneto	B-Algorithm
alternators	B-Algorithm
for	O
generation	O
.	O
</s>
<s>
In	O
large	O
sizes	O
,	O
from	O
the	O
100kW	O
to	O
MW	O
range	O
,	O
the	O
machines	O
developed	O
for	O
modern	O
wind	O
turbines	O
are	O
termed	O
permanent	B-Algorithm
magnet	I-Algorithm
synchronous	I-Algorithm
generators	I-Algorithm
.	O
</s>
<s>
One	O
popular	O
and	O
common	O
use	O
of	O
magnetos	B-Algorithm
of	O
today	O
is	O
for	O
powering	O
lights	O
and	O
USB	O
powered	O
devices	O
on	O
bicycles	O
.	O
</s>
<s>
Most	O
commonly	O
,	O
a	O
small	O
magneto	B-Algorithm
,	O
termed	O
a	O
bottle	B-Algorithm
dynamo	I-Algorithm
,	O
rubs	O
against	O
the	O
tire	O
of	O
the	O
bicycle	O
and	O
generates	O
power	O
as	O
the	O
wheel	O
turns	O
.	O
</s>
<s>
More	O
expensive	O
and	O
less	O
common	O
but	O
more	O
efficient	O
is	O
the	O
hub	O
dynamo	B-Language
that	O
rotates	O
neodymium	O
magnets	O
around	O
a	O
copper	O
coil	O
in	O
a	O
claw	O
pole	O
cage	O
inside	O
the	O
hub	O
of	O
a	O
wheel	O
.	O
</s>
<s>
Commonly	O
referred	O
to	O
as	O
dynamos	B-Language
,	O
both	O
devices	O
are	O
in	O
fact	O
magnetos	B-Algorithm
,	O
producing	O
alternating	O
current	O
as	O
opposed	O
to	O
the	O
direct	O
current	O
produced	O
by	O
a	O
true	O
dynamo	B-Language
.	O
</s>
<s>
The	O
magneto	B-Algorithm
also	O
had	O
a	O
medical	O
application	O
for	O
treatment	O
of	O
mental	O
illness	O
in	O
the	O
beginnings	O
of	O
electromedicine	O
.	O
</s>
<s>
In	O
1850	O
,	O
Duchenne	O
de	O
Boulogne	O
,	O
a	O
French	O
doctor	O
,	O
developed	O
and	O
manufactured	O
a	O
magneto	B-Algorithm
with	O
a	O
variable	O
outer	O
voltage	O
and	O
frequency	O
,	O
through	O
varying	O
revolutions	O
by	O
hand	O
or	O
varying	O
the	O
inductance	O
of	O
the	O
two	O
coils	O
,	O
for	O
clinical	O
experiments	O
in	O
neurology	O
.	O
</s>
<s>
Magnetos	B-Algorithm
adapted	O
to	O
produce	O
impulses	O
of	O
high	O
voltage	O
for	O
spark	O
plugs	O
are	O
used	O
in	O
the	O
ignition	O
systems	O
of	O
spark-ignition	O
piston	O
engines	O
.	O
</s>
<s>
Magnetos	B-Algorithm
are	O
used	O
in	O
piston	O
aircraft	O
engines	O
for	O
their	O
reliability	O
and	O
simplicity	O
,	O
often	O
in	O
pairs	O
.	O
</s>
<s>
Motor	O
sport	O
vehicles	O
such	O
as	O
motorcycles	O
and	O
snowmobiles	O
may	O
use	O
magnetos	B-Algorithm
because	O
they	O
are	O
lighter	O
in	O
weight	O
than	O
an	O
ignition	O
system	O
relying	O
on	O
a	O
battery	O
.	O
</s>
<s>
Small	O
internal	O
combustion	O
engines	O
used	O
for	O
lawn	O
mowers	O
,	O
chain	O
saws	O
,	O
portable	O
pumps	O
and	O
similar	O
applications	O
use	O
magnetos	B-Algorithm
for	O
economy	O
and	O
weight	O
reduction	O
.	O
</s>
<s>
Magnetos	B-Algorithm
are	O
not	O
used	O
in	O
highway	O
motor	O
vehicles	O
that	O
have	O
a	O
cranking	O
battery	O
,	O
which	O
may	O
need	O
more	O
ignition	O
timing	O
control	O
than	O
a	O
magneto	B-Algorithm
system	O
can	O
provide	O
,	O
though	O
sophisticated	O
solid	O
state	O
controllers	O
are	O
becoming	O
more	O
common	O
.	O
</s>
<s>
Manual	O
telephones	O
for	O
local	O
battery	O
station	O
service	O
in	O
magneto	B-Algorithm
exchanges	O
were	O
equipped	O
with	O
a	O
hand-cranked	O
magneto	B-Algorithm
generator	O
to	O
produce	O
an	O
alternating	O
voltage	O
to	O
alert	O
the	O
central	O
office	O
operator	O
,	O
or	O
to	O
ring	O
the	O
bells	O
of	O
other	O
telephones	O
on	O
the	O
same	O
(	O
party	O
)	O
line	O
.	O
</s>
<s>
The	O
development	O
of	O
modern	O
rare-earth	O
magnets	O
makes	O
the	O
simple	O
magneto	B-Algorithm
alternator	B-Algorithm
a	O
more	O
practical	O
proposition	O
as	O
a	O
power	O
generator	O
,	O
as	O
these	O
permit	O
a	O
greatly	O
increased	O
field	O
strength	O
.	O
</s>
<s>
By	O
the	O
late	O
1980s	O
,	O
developments	O
in	O
magnetic	O
materials	O
such	O
as	O
samarium	O
–	O
cobalt	O
,	O
an	O
early	O
rare-earth	O
type	O
,	O
let	O
permanent	O
magnet	O
alternators	B-Algorithm
be	O
used	O
in	O
applications	O
that	O
require	O
an	O
extremely	O
robust	O
generator	O
.	O
</s>
<s>
In	O
guided	O
missiles	O
,	O
such	O
generators	O
can	O
replace	O
a	O
flux	B-Algorithm
switching	I-Algorithm
alternator	I-Algorithm
.	O
</s>
