ELECTRONICS - [alarm system] - [page 2/9]
2. EXISTING HARDWARE
:: 2.1 Sensors
At doors and windows, glass break sensors are installed. To detect if the doors opens,
magnetic sensors were used. Motion detectors couldn't be used
:: 2.2 Code Lock
The access code for the delayed zone must be entered by a code lock. I've chosen
for the Velleman key lock. The lock was modified so, that the LED lights up when the
delayed zone is active. Another modification is that the relay in the lock just
gives a pulse when the correct code is entered. A third modification was the adding
of a little buzzer. It starts beeping when the door is opened, when the alarm is
active. This is to notify the user, that the system is expecting him to enter a
password. If no password is entered within 15 seconds, the siren goes off.
:: 2.3 Kojak Siren
The siren sound is produced by the Velleman Kojak siren. I've chosen for this
siren, because you can completely configure the sound generates.
:: 2.4 Alarm Control Panel
The alarm is turned on and off by a control panel. This panel was already
present before I designed the alarm. All I had to do was to make the alarm
compatible with the control panel.