Tilt/Vibration Sensor

[aratti]

RS components has a lot of tilt switches, see this link: http://uk.rs-online.com/web/c/?searc...es&sra=oss&r=t

Cheers

Al.

[AvionicsMaster1]

For me simple is better. If I can put a capacitor or resistor/capacitor on something rather than write many lines of code that's better than taking the time to make the code work.

Your location says Greece so any link in the U.S. might not be viable but mercury tilt switches are fairly common here. If you have an old thermostat, the ones with the slide for setting temperature not digital, they have a mercury switch in them.

[Demon]

A variant on the wire/spring idea; use the coiled spring from an old thermostat. Add a drop of lead on the tip to act as contact.

You might be able to have two axis by placing two springs perpendicular.

This of course is totally theoretical.

Robert

[Jerson]

A quick image search on google for 'mercury tilt switch' showed a lot of those bulbs and 'non-mercury tilt switches' are now the norm.

I found some commercial vibration sensors using the spring sensor here
http://www.aliexpress.com/store/grou...210931515.html

[Ioannis]

Mercury is not allowed anymore. So other solutions like the spring type or ball like the one I am using is prefered.

I have ordered a packet of 200 pcs spring type sensor and will see if it works as expected. Since this is a production design, I cannot experiment with diy coils or springs. Thanks all for the ideas, but a ready made solution is prefered.

I have a feeling that either sensor, the one I am using now (see the pdf on the #1 post), or the spring type, it will need some kind of filtering or integration. Maybe the idea of a resistor-capacitor will help as AvionincsMaster1 posted.

Ioannis

[AvionicsMaster1]

Woohoo! I might have gotten something right!

Have you thought about using something like this:ADXL345 3-axis Digital Tilt Sensor Acceleration Module. I know it's for Arduino but I'm sure a similar solution could be forund for PBP and they're fairly cheap but I was too lazy to look for one. They probably aren't as cheap as your vibration sensor though.

I did find some two axis tilt sensors but if you're doing an alarm you might want the three axis and I think an accel would work well. The math for it looks daunting http://www.freescale.com/files/senso...ote/AN3461.pdf. You could also use IOC with the accels which I think would be easier by just looking for a raw voltage change. I realize this system probably won't be used in the National Art Gallery but it could be made to be fairly sensitive using accelerometers.

Good luck.

[Ioannis]

I forgot to mention that the circuit will be battery powered with the need to work for a long time. Say for months. MCU will be in sleep and when shaked, an interrupt wakes it, does its magic and goes back to sleep as a good kid.

Thanks for the moduleidea, it is a good but is very expensive for this project. The target price per device is about 7-10 euros max.

So for now, I'll stick with the mechanical sensors.

Ioannis