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Central Locking Interface
Some cheap car alarms do not have a connection for the central locking system. However, in most it should be possible to find a point in the alarm circuit which is high when the alarm is activated and low when it is off. This signal can then be used to drive this relay circuit to operate the central locking system. The interface circuit converts each toggle of the alarm signal to a brief pulse to operate the two relays which then are then connected in parallel with appropriate contacts on the master solenoid in the central locking system.
Author: Frank Keller – Copyright: Silicon Chip