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Thread: Light level meter output, circumvention of bouncing levels (cloud cover etc)

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    Automated Home Ninja marcuslee's Avatar
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    Default Light level meter output, circumvention of bouncing levels (cloud cover etc)

    Hi Guys,

    I use a light level output for a sensor in rear eave. What I do is have a set of blackout blinds open part way at sunrise, then when full sunlight starts (and it goes above output level 70 in this case), to open blackout blinds fully.

    Something I didn't appreciate, until I added a sound file to when the house executes this functionality (to pre-alert occupants, instead of startling them!), is that during the sunrise, whilst light level is going up, occasionally a cloud floats by meaning it's just past the threshold, and then it drops below the threshold for a bit, before it then goes up past the threshold again once the cloud has gone.

    Any advice for how to overcome / what others have done?

    I'm thinking two light level inputs (maybe front and rear??) and averaging them somehow (with some logic gate), to remove this single dependence?

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    Automated Home Legend Karam's Avatar
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    You can set up a user defined threshold rather than use the main dark/bright output, in which case you have control of the hysteresis value. This avoids slowing down the signal dynamics, but on the other hand if you feel you'd like to smooth out a signal there are various ways of doing that too e.g pass via a low pass filter (in gates) to virtual light level object. There is also some (cruder) control of low pass filtering coefficient in some modules themselves i.e at firmware level.

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    Automated Home Legend chris_j_hunter's Avatar
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    interesting - we, too, have taken to using the intercom to let us know what's going on, to avoid surprises ... and also to, sometimes temporarily, help us asses whether new logic is doing what we expected and/or needs to be adjusted in some way ...

    we're looking to add blinds to a couple of windows - we've got DRB relays ready & waiting, but what blinds / motors did you go for - have they been reliable ?

  4. #4
    Automated Home Ninja marcuslee's Avatar
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    Quote Originally Posted by Karam View Post
    You can set up a user defined threshold rather than use the main dark/bright output, in which case you have control of the hysteresis value. This avoids slowing down the signal dynamics, but on the other hand if you feel you'd like to smooth out a signal there are various ways of doing that too e.g pass via a low pass filter (in gates) to virtual light level object. There is also some (cruder) control of low pass filtering coefficient in some modules themselves i.e at firmware level.
    Brilliant, thanks for reply Karam. That's exactly what's needed, and indeed missed that feature already built into Cortex for this exact kind of thing to overcome!

  5. #5
    Automated Home Ninja marcuslee's Avatar
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    Quote Originally Posted by chris_j_hunter View Post
    interesting - we, too, have taken to using the intercom to let us know what's going on, to avoid surprises ... and also to, sometimes temporarily, help us asses whether new logic is doing what we expected and/or needs to be adjusted in some way ...

    we're looking to add blinds to a couple of windows - we've got DRB relays ready & waiting, but what blinds / motors did you go for - have they been reliable ?
    Hi Chris, quietness (and reliability) were my main objectives. Also I didn't really want to use DC motors, meaning another potential issue (vs 240v) ones.

    And that lead me to Somfy blinds (can't remember what the other brand was which made my short list. Possibly Lutron?), and for my Veluxes, Velux blinds.

    They've been excellent. In fact, better than my expectations. Also I'd originally thought (and planned for) taking over manual 240v switching characteristics directly with Idratek/Cortex, for up, down, intermediate positions (and had schematics drawn up as such), but in the end it was overkill, and my temporary solution worked and I've left it at this;
    - Somfy blinds, with RF remote
    - then manually hacking the RF remote buttons to be switched by Idratek, ie to hit the up, down and 'fav' button (which stops the blinds midway)

    I'd gone to the trouble (and expense) of installing Somfy blinds, that had separate RF receiver/logic boxes, such that I could hack into the box to have Idratek switch the 240v lines, necessary, but this was a waste of time. And indeed subsequent blinds, I've begun ordering the more common Somfy models, where the motor and RF receiver is built into the blind itself.

    I should add, I did also consult with a UK Somfy tech (via one of their larger installers), and actually that was their original proposal (which I chose to override at the time)!

  6. #6
    Automated Home Legend chris_j_hunter's Avatar
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    Marcus -

    many thanks, good to know ...

    hacking the remote sounds like what we did for our motorised bed bases - for which, once opened-up, the button connections took some deciphering - it was as though whoever designed it had either got bored & decided to do it complicated, for fun, or maybe there'd been other modes which hadn't make it into production) ...

    Chris

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