|
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.
Click Here to View
Circuits
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.
Click Here to View
Circuits
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. |
