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Posted

I'm looking for a standalone external motion sensor/switch which I can use to control lighting, and also act as a perimeter sensor for a future alarm system. In an ideal world it'll have a DPST or DPDT switch rather than the SPST or SPDT switched terminal in the rear like they usually do.  That way I can use one pole to switch the mains, and the other as a volt-free contact or such for an alarm interface.

Does such a thing exist?

Posted

I suspect that you won't find one due to the required separation between 240VAC and the other volt-free contact. A different approach might be to find a 'smart' PIR that you could integrate with alarm and smart lights using IFTTT but I could only find indoor versions of that. From there it depends on how much tinkering you're prepared to do, as with all things electronic, you can do almost anything you can dream of with a little bit of know-how. Any SPST 240V outdoor PIR can power a relay with 240VAC coil to give you an additional volt-free contact.

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Posted
23 minutes ago, Radian said:

I suspect that you won't find one due to the required separation between 240VAC and the other volt-free contact. A different approach might be to find a 'smart' PIR that you could integrate with alarm and smart lights using IFTTT but I could only find indoor versions of that. From there it depends on how much tinkering you're prepared to do, as with all things electronic, you can do almost anything you can dream of with a little bit of know-how. Any SPST 240V outdoor PIR can power a relay with 240VAC coil to give you an additional volt-free contact.

This is more or less what I did. Mains PIR driving a 240V primary relay with 24V on the secondary in a cabinet.

Problem was the relays were dreadfully noisy and banged away all night whenever wildlife passed by 

So I replaced them with cheap mains to 5V switched mode power supply (i.e. any old usb charger) which is silent. But still too many false triggers, so now all driven by Frigate image recognition running off the CCTV cameras 🙂

 

 

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Posted
5 minutes ago, Temp said:

 

Yes, an opto board like that would work instead of a relay and get around @joth's clicky noise problem, but it's all a bit exposed at the lethal end. With care though it could be a solution that might fit inside the PIR casing.

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Posted
22 minutes ago, Radian said:

 

Yes, an opto board like that would work instead of a relay and get around @joth's clicky noise problem, but it's all a bit exposed at the lethal end. With care though it could be a solution that might fit inside the PIR casing.

 

I was thinking you could run three core & earth to each PIR. So you have power to the PIR and switched live coming back to a box in the house. Then run switched live to the light(s) from there. Put the relay or onto isolators in another box in the house. I 3D printed a box for the Arduino with a wall for isolation but it could do with improving.

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Posted
9 hours ago, TonyT said:

What about quinetic pir and floodlights?

I see you can pair those with lots of things but couldn't see a simple volt-free switch output for triggering an alarm.

Posted
1 minute ago, TonyT said:

Can you not use a relay connected to the lamp output to give you a volt free contact?

Beat me to it 👍

Posted
Just now, joe90 said:

Beat me to it 👍

 

12 hours ago, Radian said:

Any SPST 240V outdoor PIR can power a relay with 240VAC coil to give you an additional volt-free contact.

 

  • Like 1
Posted
12 hours ago, joth said:

This is more or less what I did. Mains PIR driving a 240V primary relay with 24V on the secondary in a cabinet.

Problem was the relays were dreadfully noisy and banged away all night whenever wildlife passed by 

 

Posted

Thanks all for your thoughts and comments.  I'm having PIRs in a separate location to the light sources, so I don't want to be dependent on an 'all in one' type fitting (these frequently cause problems when they eventually fail too).
I'm running 3C+E across all fittings and sensors so there's always switched and permanent live present - the problem with using the the switched live as an indicator of motion is the scenarios when the switched live is energized from the (non PIR) switch which is also on the circuit as an override - admittedly this would usually be in a situation when the alarm isn't set, but it does leave the installation vulnerable under certain scenarios.

 

Posted
14 hours ago, TonyT said:

the alarm is a "something for the future" rather than a right now job, but everything I'm working on now, I'd like to fit with an alarm in mind.

 

This GID stuff looks interesting though :)

 

G

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