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timer circuit

Posted: Tue Feb 11, 2003 2:36 pm
by notstock78
I am looking for an idea on how to make a timer circit that will shut off a car alarm after about 60 seconds. I am open to any suggestions.
Thank You

Re: timer circuit

Posted: Tue Feb 11, 2003 4:53 pm
by natcsparky
Hi, <p>I would suggest that you check out some circuit diagrams available at the local radio shack in a series by Forrest Mimms call engineers notebook. They have one called timer / OPAMP circuits (I believe). In there you will see several circuits using a 555 timer IC to do just what you describe. Long durations require ganging the 555s if I remember right. If you can't find one, email me and I can send you some useful circuit diagrams.

Re: timer circuit

Posted: Tue Feb 11, 2003 6:14 pm
by Dimbulb
Since every circuit will be a little different more specifics are needed. A typical alarm has a sensor and a disarm or reset. the sensor buffer starts the timer and when the timer changes state it sends a reset.<p>What kind of sensor ? Is there a momentary switch for reset?