Page 2 of 5 FirstFirst 12345 LastLast
Results 11 to 20 of 48

Thread: Reed Switches & PIRs

  1. #11
    Moderator Kevin's Avatar
    Join Date
    Jan 2004
    Location
    West Yorkshire
    Posts
    554

    Default

    Another great topic :-)

    I'm one of the 'rarely close internal doors' types so the doorway sensors are going to be important to me. Most of my doorways are deep fortunately as my walls are very thick. A while back I bought some of the Maxbotix tiny ultrasonic sensors and Gerrys PCB to control them. Like so many of my intents - they're still in the box though.

    My idea was to mount them pointing across or above the doorways, and use the reported distance to limit any 'into room' operation. . Above the door appealed because I wondered if I might be able to get any height indication of people - so some 'who' detection. Then I had the idea that if I mounted them at the side of the door pointing diagonally into or out of a room I could also get an indication of whether someone was entering or leaving the room based on the distance indication - short to long or long to short. My deep doorways will help - at one stage Gerry was considering adding this interpretation into the controller - just a binary IN|OUT indicator - again with range limiting for the into room sensing removal. This is the route I still intend to take as it would be helpful in getting more accurate, and faster room occupancy sensing and counting . Having a direction indication input within Cortex would be useful too - feature request ;-).

    I do use some of those Pulsor strain gauge sensors around the house - they can be very sensitive and how and where you mount them is key to successful operation. Unfortunately due to the epoxy mounting system getting it wrong usually means you sacrifice the sensor. I was trying to use them around the sofas to detect when people sat down /dozed - but I still haven't got that working usefully. The sensors obviously only report change and not constant weight. On the lookout just for some weight sensors that might be useable like castor cups here. I tried some Pulsors in the doorway entrances and on the stairs and even on the terrace flagstones outside.

    Although I have trawled the internet I haven't found any really tiny IR break beam sensors - I was hoping to find something about the size of the keyring type IR pointer devices - ie pencil widths - that could be sunk inconspicuosly into door surrounds - separate TX and Rx units probably as reflection might not be dependable - but no luck so far which is surprising as I'm sure they must exist. If anyone know of any do let me know.. They would need to be light immune - with modulated/coded beam to allow for two beams without interference.

    Cheers K
    Last edited by Kevin; 24th March 2008 at 11:26 AM.

  2. #12
    Automated Home Ninja Viv's Avatar
    Join Date
    Dec 2004
    Posts
    284

    Default PIR as Proximity sensor

    Quote Originally Posted by chris_j_hunter View Post
    but got to thinking about putting a PIR sensor immediately above the doorway, perhaps with a short tube over the sensor, to limit its field of view, instead-of or as-well, to better sense comings & goings ... hmmm, would it work (with Cortex) ?...
    You could use such a designed PIR as a proximity sensor in the doorway. You would configure a digital input as a proximity object. It is then connected to the door object it is monitoring.

    As someone was detected walking through the door it would clear the presence in both rooms. You would expect a conventionally placed PIR to then locate which room the person is in.

    The advantage of having such a sensor is that presence can be registered in both rooms either side of the door when the door is open i.e. the logic does not move the presence between the rooms. This is because the proximity sensor in effect creates a barrier (a bit like the door is closed).

  3. #13
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,674

    Default

    >PIR as a proximity-sensor ...

    yep, only the PIR would not be a simple switch, so might add complications ... how easily could the logic / Cortex cope ?

    >the logic does not move the presence between the rooms ... because the proximity sensor in-effect creates a barrier ...

    not sure I follow ! Again, though, the PIR behaviour may be complicated - eg: how locally will it be sensing ?

    BTW ... was looking at our uPVC french-windows today, to see how to add reed-switches ... and wondering about how to put them in the jam, inconspicuously / reliably, and whether it would be possible to sense the locking-mechanism ... hmmm !
    Last edited by chris_j_hunter; 31st March 2008 at 06:18 AM. Reason: clarity

  4. #14
    Automated Home Ninja Viv's Avatar
    Join Date
    Dec 2004
    Posts
    284

    Default

    Quote Originally Posted by chris_j_hunter View Post
    >PIR as a proximity-sensor ...

    yep, only the PIR would not be a simple switch, so might add complications ... how easily could the logic / Cortex cope ?
    The proximity object receives a true state when someone passes its sensor. A PIR looking down at the floor from above the door will generate a pulse as someone passes through. Provided it does not generate a false trigger from someone simply in the room it should work fine.

    Quote Originally Posted by chris_j_hunter View Post
    >PIR as a proximity-sensor ...
    not sure I follow ! Again, though, the PIR behaviour may be complicated - eg: how locally will it be sensing ?
    Consider two adjacent rooms A and B have an open door. A PIR detection in room A will register presence in room A. A PIR detection in room B will then register presence in room B and remove presence from room A. PIR detection in room A will register presence in room A and remove it from room B and so on (unless the go off in other rooms). If the door was closed then presence would be registered in room A and room B if both PIR's triggered.

    The use of a proximity sensor in the doorway allows both rooms to have simultaneous presence registered (if valid) with the door open.

  5. #15
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,674

    Default

    thanks ...

    looking at our doorways (& doorless doorways) today, it might be more convenient / aesthetically better to put the PIRs on the side, rather than on the top - the back-box (and even teh face-plate) could buried, rather than surface-mounted ... the tops having reinforced concrete lintels !

  6. #16
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,674

    Default

    >PIRs on the side, rather than on the top ...

    on second-thoughts, daft idea when there's a door !


    >IR break-beam sensor ...

    wonder if they wopuld have to be pulsed, for economy - ie: no idea about their power consumption ... ?

  7. #17
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,674

    Default

    Reed switches .... where else might they be useful, besides doors between rooms & doors to the outside ? Cupboards & draws, in kitchen, bathroom, wherever (but why) ?? Fridge, freezer, maybe (but how) ?? Anything else - like, maybe, for registering when things are in their place - tools, say, or ... what) ??

    Any ideas ? So we can wire accordingly, before we plaster !
    Last edited by chris_j_hunter; 1st April 2008 at 08:08 PM. Reason: afterthought !

  8. #18
    Moderator toscal's Avatar
    Join Date
    Oct 2005
    Location
    Near Alicante Spain
    Posts
    2,010

    Default

    Quote Originally Posted by chris_j_hunter View Post
    >
    >IR break-beam sensor ...

    wonder if they wopuld have to be pulsed, for economy - ie: no idea about their power consumption ... ?
    IR beam break sensors tend not to consume too much power The ones we install consume about 40 to 50mA. So not that much really.

  9. #19
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,674

    Default

    >IR beam-breaker ...

    which ones do you use ... are some better than others ??

    ----

    >50mA ...

    ie: 50/100 x say 10V x 24 x 365 / 1000 kWhr per annum @ say 7p each = about 30p per year ...

    real cost maybe half that, because helps heat the house !

    sorry, had to do the sum !

  10. #20
    Moderator toscal's Avatar
    Join Date
    Oct 2005
    Location
    Near Alicante Spain
    Posts
    2,010

    Default

    I think they are Optex, as they tend to arrive unbranded. They are similar to these http://www.optexeurope.com/Site/temP...100&intLevel=6
    There are many types.
    Some have the emitter and receiver in one unit and then require a reflector.
    Others have an emitter in one unit and a receiver in the other. And some use dual or quad beam systems where you have more than one beam. And the beams may be on different frequencies of the infra red spectrum.
    The ones we use are of the dual beam variety, and are quite reasonable in price about 110 euros.
    You may want to have a look at these sensors http://www.optexeurope.com/Site/temP...g=2&intLevel=5
    Never used them so don't know how well they work.

    You could make your own optical beam if you are handy with a soldering iron http://www.electronic-circuits-diagr...rmsckt19.shtml
    Last edited by toscal; 2nd April 2008 at 11:30 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •