<s>
An	O
ignition	B-Algorithm
magneto	I-Algorithm
(	O
also	O
called	O
a	O
high-tension	O
magneto	B-Algorithm
)	O
is	O
an	O
older	O
type	O
of	O
ignition	O
system	O
used	O
in	O
spark-ignition	O
engines	O
(	O
such	O
as	O
petrol	O
engines	O
)	O
.	O
</s>
<s>
It	O
uses	O
a	O
magneto	B-Algorithm
and	O
a	O
transformer	B-Algorithm
to	O
make	O
pulses	O
of	O
high	O
voltage	O
for	O
the	O
spark	O
plugs	O
.	O
</s>
<s>
Used	O
on	O
many	O
cars	O
in	O
the	O
early	O
20th	O
century	O
,	O
ignition	B-Algorithm
magnetos	I-Algorithm
were	O
largely	O
replaced	O
by	O
induction	O
coil	O
ignition	O
systems	O
.	O
</s>
<s>
The	O
use	O
of	O
ignition	B-Algorithm
magnetos	I-Algorithm
is	O
now	O
confined	O
mainly	O
to	O
engines	O
without	O
a	O
battery	O
,	O
for	O
example	O
in	O
lawnmowers	O
and	O
chainsaws	O
.	O
</s>
<s>
A	O
simple	O
magneto	B-Algorithm
(	O
an	O
electrical	O
generator	O
using	O
permanent	O
magnets	O
)	O
is	O
able	O
to	O
produce	O
relatively	O
low	O
voltage	O
electricity	O
,	O
however	O
it	O
is	O
unable	O
to	O
produce	O
the	O
high	O
voltages	O
required	O
by	O
a	O
spark	O
plug	O
as	O
used	O
in	O
most	O
modern	O
engines	O
(	O
aside	O
from	O
diesel	O
engines	O
)	O
.	O
</s>
<s>
An	O
ignition	B-Algorithm
magneto	I-Algorithm
also	O
includes	O
an	O
electrical	O
transformer	B-Algorithm
,	O
which	O
converts	O
the	O
electricity	O
to	O
a	O
higher	O
voltage	O
(	O
with	O
the	O
trade-off	O
being	O
a	O
corresponding	O
reduction	O
in	O
the	O
output	O
current	O
)	O
.	O
</s>
<s>
In	O
the	O
type	O
known	O
as	O
a	O
shuttle	O
magneto	B-Algorithm
,	O
the	O
engine	O
rotates	O
a	O
coil	O
of	O
wire	O
between	O
the	O
poles	O
of	O
a	O
magnet	O
.	O
</s>
<s>
In	O
the	O
inductor	O
magneto	B-Algorithm
,	O
the	O
magnet	O
is	O
rotated	O
and	O
the	O
coil	O
remains	O
stationary	O
.	O
</s>
<s>
One	O
or	O
more	O
times	O
per	O
revolution	O
,	O
just	O
as	O
the	O
magnet	O
pole	O
moves	O
away	O
from	O
the	O
coil	O
and	O
the	O
magnetic	O
flux	O
begins	O
to	O
decrease	O
,	O
a	O
cam	B-Data_Structure
opens	O
the	O
contact	O
breaker	O
(	O
called	O
"	O
the	O
points	O
"	O
in	O
reference	O
to	O
the	O
two	O
points	O
of	O
a	O
circuit	O
breaker	O
)	O
and	O
interrupts	O
the	O
current	O
.	O
</s>
<s>
A	O
second	O
coil	O
,	O
with	O
many	O
more	O
turns	O
than	O
the	O
primary	O
,	O
is	O
wound	O
on	O
the	O
same	O
iron	O
core	O
to	O
form	O
an	O
electrical	O
transformer	B-Algorithm
.	O
</s>
<s>
On	O
more	O
advanced	O
magnetos	B-Algorithm
the	O
cam	B-Data_Structure
ring	O
can	O
be	O
rotated	O
by	O
an	O
external	O
linkage	O
to	O
alter	O
the	O
ignition	O
timing	O
.	O
</s>
<s>
In	O
a	O
modern	O
installation	O
,	O
the	O
magneto	B-Algorithm
only	O
has	O
a	O
single	O
low	O
tension	O
winding	O
which	O
is	O
connected	O
to	O
an	O
external	O
ignition	O
coil	O
which	O
not	O
only	O
has	O
a	O
low	O
tension	O
winding	O
,	O
but	O
also	O
a	O
secondary	O
winding	O
of	O
many	O
thousands	O
of	O
turns	O
to	O
deliver	O
the	O
high	O
voltage	O
required	O
for	O
the	O
spark	O
plug(s )	O
.	O
</s>
<s>
Initially	O
this	O
was	O
done	O
because	O
it	O
was	O
easier	O
to	O
provide	O
good	O
insulation	O
for	O
the	O
secondary	O
winding	O
of	O
an	O
external	O
coil	O
than	O
it	O
was	O
in	O
a	O
coil	O
buried	O
in	O
the	O
construction	O
of	O
the	O
magneto	B-Algorithm
(	O
early	O
magnetos	B-Algorithm
had	O
the	O
coil	O
assembly	O
externally	O
to	O
the	O
rotating	O
parts	O
to	O
make	O
them	O
easier	O
to	O
insulate	O
—	O
at	O
the	O
expense	O
of	O
efficiency	O
)	O
.	O
</s>
<s>
In	O
more	O
modern	O
times	O
,	O
insulation	O
materials	O
have	O
improved	O
to	O
the	O
point	O
where	O
constructing	O
self-contained	O
magnetos	B-Algorithm
is	O
relatively	O
easy	O
,	O
but	O
energy	O
transfer	O
systems	O
are	O
still	O
used	O
where	O
the	O
ultimate	O
in	O
reliability	O
is	O
required	O
such	O
as	O
in	O
aviation	O
engines	O
.	O
</s>
<s>
Because	O
the	O
magneto	B-Algorithm
has	O
low	O
voltage	O
output	O
at	O
low	O
speed	O
,	O
starting	O
an	O
engine	O
is	O
more	O
difficult	O
.	O
</s>
<s>
Therefore	O
,	O
some	O
magnetos	B-Algorithm
have	O
an	O
impulse	O
coupling	O
,	O
a	O
springlike	O
mechanical	O
linkage	O
between	O
the	O
engine	O
and	O
magneto	B-Algorithm
drive	O
shaft	O
which	O
"	O
winds	O
up	O
"	O
and	O
"	O
lets	O
go	O
"	O
at	O
the	O
proper	O
moment	O
for	O
spinning	O
the	O
magneto	B-Algorithm
shaft	O
.	O
</s>
<s>
The	O
impulse	O
coupling	O
uses	O
a	O
spring	O
,	O
a	O
hub	O
cam	B-Data_Structure
with	O
flyweights	O
,	O
and	O
a	O
shell	O
.	O
</s>
<s>
The	O
hub	O
of	O
the	O
magneto	B-Algorithm
rotates	O
while	O
the	O
drive	O
shaft	O
is	O
held	O
stationary	O
,	O
and	O
the	O
spring	O
tension	O
builds	O
up	O
.	O
</s>
<s>
When	O
the	O
magneto	B-Algorithm
is	O
supposed	O
to	O
fire	O
,	O
the	O
flyweights	O
are	O
released	O
by	O
the	O
action	O
of	O
the	O
body	O
contacting	O
the	O
trigger	O
ramp	O
.	O
</s>
<s>
This	O
allows	O
the	O
spring	O
to	O
unwind	O
giving	O
the	O
rotating	O
magnet	O
a	O
rapid	O
rotation	O
and	O
letting	O
the	O
magneto	B-Algorithm
spin	O
at	O
such	O
a	O
speed	O
to	O
produce	O
a	O
spark	O
.	O
</s>
<s>
The	O
first	O
person	O
to	O
develop	O
the	O
idea	O
of	O
a	O
high-tension	O
magneto	B-Algorithm
was	O
André	O
Boudeville	O
,	O
but	O
his	O
design	O
omitted	O
a	O
condenser	O
(	O
capacitor	O
)	O
.	O
</s>
<s>
In	O
the	O
late	O
1890s	O
,	O
English	O
engineer	O
Frederick	O
Richard	O
Simms	O
and	O
German	O
engineer	O
Robert	O
Bosch	O
developed	O
the	O
first	O
practical	O
high-tension	O
magneto	B-Algorithm
.	O
</s>
<s>
The	O
first	O
car	O
to	O
use	O
magneto	B-Algorithm
ignition	I-Algorithm
was	O
the	O
1901	O
German	O
Mercedes	O
35	O
hp	O
racing	O
car	O
,	O
followed	O
by	O
various	O
cars	O
produced	O
by	O
Benz	O
,	O
Mors	O
,	O
Turcat-Mery	O
,	O
and	O
Nesseldorf	O
.	O
</s>
<s>
Ignition	B-Algorithm
magnetos	I-Algorithm
were	O
soon	O
was	O
used	O
on	O
most	O
cars	O
,	O
for	O
both	O
low	O
voltage	O
systems	O
(	O
which	O
used	O
secondary	O
coils	O
to	O
fire	O
the	O
spark	O
plugs	O
)	O
and	O
high	O
voltage	O
magnetos	B-Algorithm
(	O
which	O
fired	O
the	O
spark	O
plug	O
directly	O
,	O
similar	O
to	O
induction	O
coil	O
ignition	O
)	O
.	O
</s>
<s>
Ignition	B-Algorithm
magnetos	I-Algorithm
were	O
largely	O
replaced	O
by	O
ignition	O
coils	O
once	O
batteries	O
became	O
common	O
in	O
cars	O
,	O
since	O
a	O
battery-operated	O
coil	O
can	O
provide	O
a	O
high-voltage	O
spark	O
even	O
at	O
low	O
speeds	O
,	O
making	O
starting	O
easier	O
.	O
</s>
<s>
Because	O
it	O
requires	O
no	O
battery	O
or	O
other	O
source	O
of	O
electrical	O
energy	O
,	O
the	O
magneto	B-Algorithm
is	O
a	O
compact	O
and	O
reliable	O
self-contained	O
ignition	O
system	O
,	O
which	O
is	O
why	O
it	O
remains	O
in	O
use	O
in	O
many	O
general	O
aviation	O
applications	O
.	O
</s>
<s>
Since	O
the	O
beginning	O
of	O
World	O
War	O
I	O
in	O
1914	O
,	O
magneto-equipped	O
aircraft	O
engines	O
have	O
typically	O
been	O
dual-plugged	O
,	O
whereby	O
each	O
cylinder	O
has	O
two	O
spark	O
plugs	O
,	O
with	O
each	O
plug	O
having	O
a	O
separate	O
magneto	B-Algorithm
system	O
.	O
</s>
<s>
Dual	O
plugs	O
provide	O
both	O
redundancy	O
should	O
a	O
magneto	B-Algorithm
fail	O
,	O
and	O
better	O
engine	O
performance	O
(	O
through	O
enhanced	O
combustion	O
)	O
.	O
</s>
