how alarm sensors work?

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=90204
Printed Date: May 05, 2025 at 7:57 PM

Topic: how alarm sensors work?

Posted By: megatfauzi76
Subject: how alarm sensors work?
Date Posted: February 08, 2007 at 3:30 AM

Hai..

Can i know the concepts and the theory...how alarm sensirs works? Example...Glass Break Sensors...From what I know..it have 3 wires...

1st wire - To +ve supply

2nd wire - To -ve supply

3rd wire -ve output from the sensors

Ist correct? Meanning to said...the alarm will trigger when receive -ve current rite? What the voltage of the current?

Replies:

Posted By: brhaugen
Date Posted: February 08, 2007 at 6:45 AM

Your are correct, the signal sent on the 3rd (trigger) wire is very small in the neighborhood of 300ma depending on the mfg.

Posted By: KPierson
Date Posted: February 08, 2007 at 7:52 AM

Most present day alarm sensors are considered 'power' sensors. Powered sensors have built in processing of the actual sensor, so they require a constant source of power. The onboard processor then controls the seperate (-) outputs to trigger the alarm brain.

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Kevin Pierson

Posted By: megatfauzi76
Date Posted: February 08, 2007 at 6:31 PM

Means, the 3rd wire..I can hook to the door trigger rite? Alarm will trigger if the sensor detect something?

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