This
circuit
is
an
Electronic
Locker.
It
is
controlled
by a
switches
combination
(by
a
code).
There
is a
switch
matrix
on
the
door
of
the
locker.
This
one
is a
unit
of
switches
connected
into
4
arranged
of 4
columns
for
a
total
of
eight
terminals.
When
we
press
on a
switch,
this
one
establishes
the
contact
between
its
column
and
its
line.
This
switch
matrix
is
also
used
in
the
telephones,
for
example.
But
it
is
numbered
from
0 to
9
and
from
A to
F
for
a
total
of
16
switches.
To
open
the
locker,
we
have
to
press
4
specific
and
different
switches
in
the
good
order.
If
for
example
the
code
is
0,1,2,3
and
we
press
two
times
to
the
same
switches:
0,1,2,2,3
the
locker
won't
open.
In
this
circuit,
the
code
is
0,1,2,3
but
we
can
set
the
desired
code
when
we
built
de
circuit.
The
desired
line
(called
"stage"
in
the
schematic)
is
connected
to
the
ground
and
to a
pin
of
the
3.3k
resistor
and
the
other
line
is
connected
to
an
input
of
the
7408
and
to
the
other
pin
of
the
resistor.
All
the
desired
numbers
of
the
code
are
in
the
same
line.
To
set
the
order
of
the
number
of
the
code,
we
have
to
set
the
good
connection
between
the
node
of
the
7414
input
and
the
appropriate
node
of
the
capacitor.
For
example,
if
we
select
the
first
line
(y1)
and
the
code
is
0,1,2,3
the
first
number
(#1)
is
connected
to
the
top
left
contact
(x1).
The
switch
0 is
corresponding
to
x1/y1.
These
points
of
contact
are
colored
in
orange
in
the
schematic.
When
the
locker
is
locked,
the
red
LED
is
turned
on
and
the
green
LED
is
turned
off.
When
the
locker
is
opened,
the
red
LED
is
turned
off
and
the
green
LED
is
turned
on.
To
lock
the
locker,
we
can
push
any
of
the
16
switches
of
the
matrix.
The
locker
is
powered
by a
6V
source.
I
recommend
using
a 6V
rechargeable
battery
because
this
one
lasts
a
long
time
(at
least
3
full
days)
and
can
be
re-used.
Otherwise,
we
can
use
four
1.5V
battery
connected
in
serial.
These
least
only
5
hours
but
are
less
expensive.
To
save
energy,
we
can
remove
the
red
LED.
When
the
locker
is
powered
on,
it
is
locked.
The
electric
motor
or
the
inductors
close
the
door
while
a
bit
of
time
and
after,
stop
working.
When
we
open
the
locker,
the
electric
motor
or
the
inductors
open
the
door
while
a
bit
of
time
and
after,
stop
working.
To
control
the
state
of
the
door
(open
or
lock)
we
can
use
an
electric
motor
or a
pair
of
inductors.
If
we
use
a
electric
motor,
when
the
locker
is
closed,
the
motor
turns
in
the
anti-clockwise
direction
during
a
certain
time
and
moves
down
a
toothed
bar.
After
this
time,
the
motor
stops
turning
and
the
locker
remains
closed.
When
the
locker
is
opened,
the
motor
turns
in
the
clockwise
direction
during
a
certain
time
and
moves
up
the
toothed
bar.
After
this
time,
the
motor
stops
turning
and
the
locker
remains
opened.
If
we
use
two
inductors,
when
the
locker
is
closed,
the
second
inductor
works
during
a
certain
time
and
moves
left
a
magnetic
bar
by
attraction.
After
this
time,
the
inductor
stops
working
and
the
locker
remains
closed.
When
the
locker
is
opened,
the
first
inductor
works
during
a
certain
time
and
moves
right
the
magnetic
bar.
After
this
time,
the
inductor
stops
turning
and
the
locker
remains
opened.
The
buffer
(L293D)
who
controls
the
motor
or
the
inductors
has
two
Vcc
inputs
and
four
ground
connections.
The
both
Vcc
inputs
must
be
connected
to
the
+6V
and
all
ground
connections
must
be
connected
to
the
ground
of
the
circuit.
All
the
parts
of
the
circuits
are
placed
in
the
rack
except
the
DELs
and
the
switch
matrix
which
them,
are
placed
on
the
door.
