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Motion/PIR sensor with additional contacts?

Crowbar hero
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Crowbar hero Member

Crowbar hero

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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?

Radian Advanced Member

Radian

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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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joth Advanced Member

joth

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  On 23/09/2022 at 21:05, 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.

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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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Radian Advanced Member

Radian

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  On 23/09/2022 at 21:27, Temp said:

I used one of these to interface mains to an Arduino. It's used to detect when my boiler pump is running.

 

https://www.ebay.co.uk/itm/-1-Channel-Bit-AC-220V-Optocoupler-Isolation-Module-Board-Adaptive-For-PLC-/154400482521?pageci=204718bc-c2f2-4557-a2dd-49ea4e2a55af&redirect=mobile

 

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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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Temp Advanced Member

Temp

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  On 23/09/2022 at 21:36, 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.

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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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joth Advanced Member

joth

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  On 23/09/2022 at 21:31, 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 

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Crowbar hero Member

Crowbar hero

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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.

 

Crowbar hero Member

Crowbar hero

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  On 25/09/2022 at 19:21, TonyT said:


 

didn’t realise you were linking to alarm system

 

fitted these back in the day..

https://www.alertelectrical.com/gjd-emerald-3000-mk3-lighting-controller-gjd010.html?utm_source=google_shopping&gclid=EAIaIQobChMIrNfX7NSw-gIV5OjtCh3bTgIjEAQYCSABEgKytfD_BwE

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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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