For the alarm described trigger inputs can be derived from existing courtesy light and/or ignition circuits and various alarm outputs are available to permit intermittent (car horn and/or lights) and continuous (siren or piezoelectric transducer) operation. Furthermore, an output is available for disabling the vehicle's ignition system. No external 'keyswitch' is required and appropriate delay times are incorporated which permit exit and entry to and from the vehicle without sounding the alarm. The circuit is based on the 555 timer IC. Four such devices are used, three connected in monostable and one in the astable mode. The three monostable timers are used to provide the required delay times.
Document information
Versatile car alarm...
Vielseitiges Kfz-Alarmsystem
Practical Electronics ; 18 , 7 ; 62-67
1982
6 Seiten
Article (Journal)
English
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