Reed Switches & PIRs

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  • drod
    Automated Home Jr Member
    • Nov 2008
    • 30

    #31
    Originally posted by Karam View Post
    For traditional hinge doors magnets and reeds can be placed at the top of the door frame rather than side so you could potential choose to have a door deemed closed even when slightly ajar (we've seen some cases where people wanted this). Internal door sensing can be useful if you're the type of person who regularly closes doors, or you may choose just to sensorise doors that will be shut as part of your security plan
    Hi, just thinking about wiring some (internal) door sensors in and came across this thread. Originally I wasn't going to bother as we don't fully close our downstairs doors - however, mounting them as Karam describes here may be a good option.

    I just wanted to check exactly how this works. For example, if I mount the switch so the contacts meet when the door is still say 30 degrees open (enough to make sure a body can't squeeze around) then I assume the door will register closed. What happens if I continue closing the door - is the door still marked as closed, or is some programming required to get around this?

    Thanks

    Comment

    • chris_j_hunter
      Automated Home Legend
      • Dec 2007
      • 1713

      #32
      not sure I quite understand this approach ... seems to me Cortex would need to understand direction of travel, as well ...

      as an alternative, wonder if a potentiometer or pulse device could work here, ideally within the hinge, but maybe using some string (some sort of loop, or spring-return device, with the string wound around the pot' or strobe-wheel, at some point) ... ?
      Last edited by chris_j_hunter; 7 September 2009, 10:15 PM.
      Our self-build - going further with HA...

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      • Paul_B
        Automated Home Legend
        • Jul 2006
        • 608

        #33
        Not sure why you'd need to Chris. If you have a PIR either side of the door then Cortex will work out prescence and direction of travel, i.e. detection in room 1 then detection in room 2 and no detection in room 1.

        Reed switches are useful, in my opinion, for rooms like toilets, bathrooms, etc. Due to the nature of the activity the PIR may stop detecting movement and assume that the person has left. However, with the addition of the reed switch on the door then Cortex has the locked-in feature so if PIR stops detecting, but the door hasn't opened then the person must still be in the room, just not moving.

        For me this is the beauty of Cortex and Idratek it is not a bunch of individual sensors but the interaction between sensore generating synergy.

        Paul

        Comment

        • chris_j_hunter
          Automated Home Legend
          • Dec 2007
          • 1713

          #34
          yep, good points !

          indeed, there's probably an argument for having reed & other types switches on a lot of other things, too ... wonder how many Cortex could cope with ?
          Last edited by chris_j_hunter; 8 September 2009, 11:13 AM.
          Our self-build - going further with HA...

          Comment

          • drod
            Automated Home Jr Member
            • Nov 2008
            • 30

            #35
            Thanks for that info.

            I assume there's no downside to installing them and never using them; i.e I put them in with good intentions of closing the doors, but never do (or at least the kids don't) - it won't cause any confusion for Cortex will it?

            Comment

            • Paul_B
              Automated Home Legend
              • Jul 2006
              • 608

              #36
              No I can't think of a downside to be honest. As long as you have PIRs this will give the main presence. I think the logic was improved with Cortex v23 that allowed PIRs to act in different ways and auto-learn but I'm not confident I could explain this methodology. Karam, Viv or Gumby would do a better job.

              Comment

              • Karam
                Automated Home Legend
                • Mar 2005
                • 863

                #37
                Originally posted by drod View Post
                Hi, just thinking about wiring some (internal) door sensors in and came across this thread. Originally I wasn't going to bother as we don't fully close our downstairs doors - however, mounting them as Karam describes here may be a good option.

                I just wanted to check exactly how this works. For example, if I mount the switch so the contacts meet when the door is still say 30 degrees open (enough to make sure a body can't squeeze around) then I assume the door will register closed. What happens if I continue closing the door - is the door still marked as closed, or is some programming required to get around this?

                Thanks
                I think the idea is that the contacts are active through to the point where the door is closed. In other words 'closed door' range relying somewhat on magnetic reach and sensor location along the top of the door. So larger angle means closer to hinge but you have to balance this against decrease in consistency. It was mainly intended for situations where doors were perhaps not pushed to latching point - more like 5 rather than 30 degrees

                Comment

                • drod
                  Automated Home Jr Member
                  • Nov 2008
                  • 30

                  #38
                  Thanks for confirming that Karam - i'll experiment on a couple of doors shortly!

                  Comment

                  • chris_j_hunter
                    Automated Home Legend
                    • Dec 2007
                    • 1713

                    #39
                    we've been looking for workable (form & function) alternatives to reed-switches, for use in some situations, and so far our list includes these - might be useful :

                    White flat-plate mortice door-switch, push to break 2A - £3.38 - Toolstation :



                    Door light switch - £2.95 - UK Automation :



                    Sliding door switch - black - push to break - £3.90 - TLC :

                    Our self-build - going further with HA...

                    Comment

                    • toscal
                      Moderator
                      • Oct 2005
                      • 2061

                      #40
                      another way to detect door open or close is to use a linear position sensor mounted in the door frame by the hinge side. As the door closes it pushes the piston in. Maybe something like this http://www.positek.com/Overviews/p103oview.htm .
                      Or you could use a magnetic door sensor thats designed to fit into the door frame and just fit it on the hinge side of the frame. A door that is slightly ajar should close the contact in the sensor.
                      IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                      Renovation Spain Blog

                      Comment

                      • chris_j_hunter
                        Automated Home Legend
                        • Dec 2007
                        • 1713

                        #41
                        the Positeks look interesting ... any idea of price ?

                        they offer various models, with range to be specified when ordering ... - they don't look cheap !
                        Last edited by chris_j_hunter; 10 September 2009, 08:43 AM.
                        Our self-build - going further with HA...

                        Comment

                        • Paul_B
                          Automated Home Legend
                          • Jul 2006
                          • 608

                          #42
                          I had a thought about this in the early hours of this morning (don't ask!).

                          Would it be be possible to use the door handles as a trigger when someone touches them. I'm thinking along the lines of how a touch-sensitive light works with change in capacitance to light-up?

                          The beauty of opening a closed door which is monitored by a reed switch is the light is on before you eneter the room. If you are using just a PIR then you need to enter the room before the light comes on. The downside of the PIR and reed switch combination is an issue with PIRs after a door is closed. So Cortex caters for potential false positives by delaying presence detection for 5 seconds (configurable) after a door is closed.

                          Could you use the touch on a door handle to turn the light on in the opposite room and assist in the presence detection? Of course ultimately it would be good if you could isolate the door handles either side of the door to feed the room presence.

                          Only issue I can currently see is how would you connect the capacity type sensor to IdraNET taking account of door movement?

                          Paul

                          Comment

                          • toscal
                            Moderator
                            • Oct 2005
                            • 2061

                            #43
                            Nice idea. What about a door that is ajar and you don't touch the door handle to open it.
                            IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                            Renovation Spain Blog

                            Comment

                            • Paul_B
                              Automated Home Legend
                              • Jul 2006
                              • 608

                              #44
                              I thought about that but I couldn't think of solution unless you wanted to paint your doors with a substance that you use to measure capacitance. I guess the use of touch sensitive handles could possibly address most users but you still need to account for people not using the handle and just the door itself. In this scenario your back to PIR or infra-red beams

                              Paul

                              Comment

                              • toscal
                                Moderator
                                • Oct 2005
                                • 2061

                                #45
                                If the rooms are carpeted why not use pressure sensor mats underneath. Something like these http://www.maplin.co.uk/Search.aspx?...0mat&source=15
                                They are quite cheap too.
                                IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                                Renovation Spain Blog

                                Comment

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