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Basic circuit diagram of a door entry system installation
with an electronic call and speech privacy in a complex with
several blocks.
Alcad multiple entrance systems are based on the use of
microprocessor-controlled audio units (microprocessor-based
4+N system). Rather than using changeover switches to
select one of the entrance panels, the audio unit has been fi-
tted with a microprocessor that decides which entrance
panel should be activated, and deactivates the rest of the
panels in the system.
This system simplifies the cabling of the installation,
reduces the number of components and improves system
operation.
This type of installation can be treated as several installa-
tions with two entrances each joined together. On the main
entrance to the complex or residential there are as many
entrance panels as buildings inside the complex. Thus, each
entrance panel at the main entrance is associated with the
entrance panel of one of the buildings. Each pair of panels
works in the same way as a two entrance installation.
Telephones with the privacy of conversation feature
remain inactive until they are called from the entrance panel.
From a disabled telephone which has not received the call
it is not possible to hear the conversations between other tele-
phones and the entrance panels.
Operation
Each entrance panel at the main entrance end is selected
as the main panel of the system just one panel per installa-
tion, can be defined as the main one. To select it, remove
jumper J1 from the building entrance panels. The main panel
is the one which is connected by default to the system’s tele-
phones. The other panels are only activated when one of the
call buttons is pressed.
When a call button is pressed, the corresponding panel
comes on to allow communication with the telephones. The
system busy indicator light on the associated panel will start
to flash to indicate that it is disabled. If the call is made from
an entrance panel from the main entrance to the residential,
it´s possible to disable not only the building associated to
that panel but also the rest of the panels of the main entran-
ce. To do so the various panels need to be interconnected
via terminal 16.
When one of the push buttons on one of the entrance
panels is pressed the electronic call signal generated by the
audio unit (7) is sent via the call line to the corresponding
telephone (5), where it is heard on the loudspeaker of the
handset. At the same time the audio unit’s own loudspeaker
generates a sound to confirm to the visitor that the call has
been made. The audio unit also generates a control signal
(17) and (16) (in the case of the main entrance panel) that
deactivates the associated entrance panel. When the visitor
is calling from the main entrance, the audio unit generates a
control signal (16) which disables the rest of the panels at
the entrance.
The telephone that receives the call is activated by co-
nnecting its electronics internally to the common wire (2) and
the door lock release wire (1). While the telephone is acti-
vated on it is possible to open the door or communicate with
the caller by picking up the handset. Once the call is recei-
ved, the audio unit starts a 30 second timer while it waits for
the telephone handset to be picked up. If the handset is not
picked up during this time, the telephone is disabled and the
control signals (17) and (16) (in the case of the main entran-
ce) are removed, and all the panels go into the standby
state.
If the handset is picked up during this time, the electronics
associated to the telephone’s audio lines (3 and 4) is inter-
nally connected to the entrance panel. This connection sest
up the communication between the telephone and the
entrance panel. The audio unit starts a fresh 60 second
period before removing the control signals (17) and (16) (in
the case of the main entrance) and the panels go into
standby. When only 10 seconds are left a buzz will be
heard. It is possible to restart the timer either from the entran-
ce panel, by pressing the push button, or from the dwelling
end, by pressing and releasing the telephone handset’s hook
switch. After finishing the communication, when the audio
unit detects that the telephone handset has been hung up, it
removes the control signals (17) and (16) (in the case of the
main entrance) and the panels go into the standby state.
When the door lock release button on the telephone is
pressed, the active audio unit detects the closing of the lock
release circuit (1). The audio unit then sends an a/c voltage
(11 and 12) to the electric lock connected to the active
entrance panel, thus allowing the entrance door to be ope-
ned.
The common wire (2) of the telephone and entrance panel
provides the return path for all the telephone signals.
INSTALLATION WITH ELECTRONIC CALL AND PRIVACY OF
CONVERSATION IN A COMPLEX WITH SEVERAL BLOCKS
MICROPROCESSOR-BASED 4+N SYSTEM
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