Burglar Alarm System Circuit

[johno]

I am trying to find a pulse stretcher circuit that will enable the use of barrel type alarm system vibration semsors to operate the zone input of an alarm panel.

The circuit should have adjustable sensistivity for the sensor and operate a relay for a second or so.

Any help would be appreciated

 

[hyedenny]

Hi,
How about configuring a 555 as a "one-shot" and outputting it to a transistor to drive your relay? Or a logic level MOSFET or SCR instead of a relay? Whats a "barrel type" alarm??

 

[johno]

Thanks for the reply,

A barrel type vibration/inertia sensor is a device with a small gold plated ball sitting on two pins. When the window is hit the ball jumps up and opens the circuit.

The problem is that most alarm system zone inputs can't detect the short interval that the ball jumps.

I have tried a 555 pulse stretcher circuit but you have no sensitivity control, one break activates it, more or less.

There is a circuit posted using a 4081 IC (July 25, 2002) but it's intended to interface into the designers main alarm system panel and i'm not sure how to modify it to suite other alarm panel zone inputs.

Any help would be greatlly appreciated.

Johno.

 

[Russlk]

You don't want one break to activate the alarm, so how many breaks should it take to activate?

 

[spuffock]

Please learn how to program little PICs, one would make this job so easy!

 

[Russlk]

Easy for Spuffock to say, I have been trying to program a PIC for weeks now; if I had done it with 555s it would be done by now.

 

[Nigel Goodwin]

Easy for Spuffock to say, I have been trying to program a PIC for weeks now; if I had done it with 555s it would be done by now.

I've always said, and I'll say it again, you need a reasonable knowledge of assembler to use a high level language effectively - your problems stem from having no idea what you're actually doing, because the compiler insulates you from the hardware.

 

[Russlk]

Right on, Nigel. When I look at the assembled file, it makes no sense. Even tho two files are identical up to a point, one works, the other doesn't.