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Delay timer for light

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  • 13-02-2016 3:06pm
    #1
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,757 Mod ✭✭✭✭


    I am looking for a module that will allow a light to be turned off after a defined time. The light switch would need to be turned off and back on to turn the light on. It is typically used in landing/hall lights, particularly in apartment blocks and public buildings.

    light switch L
    module
    light L
    N
    N

    I would need about 250 watts capability. Time to be about 5 or 10 mins.


Comments

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    #2
    Stoner
    Registered Users Posts: 10,952 ✭✭✭✭Stoner


    just a time lag switch? about 15 euro in a wholesalers?

    http://www.amazon.co.uk/E319-PNEUMATIC-Electric-Automatic-Cupboards/dp/B005QZTFJ6


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    #3
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Usually in stairwells etc a stairwell lighting timer is used, and momentary switches at each switch location.

    If its just a single switch position, a time lag switch stoner suggests is all that`s needed.


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    #4
    meercat
    Registered Users Posts: 4,745 ✭✭✭meercat


    this question was asked recently
    my recommendation would be

    http://cpcireland.farnell.com/eterna/tls1440/electronic-time-delay-switch/dp/LA03741


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    #5
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,757 Mod ✭✭✭✭Sam Russell


    Thanks for the replies.

    What I want this for is to use this with a heated mirror. When the mirror is turned on, it stays on for 10 mins and then turns off. If it is required to be on longer, then it is turned off and on again.

    I also want it for the bathroom fan so that if someone leaves the bathroom light on (as often happens) the fan stops after 10 mins. The fan currently continues for 5 mins after the light has turned off, which is not a problem, but it would probably burn out if the fan was left running for many hours.

    I need a small block type of module (with three or four terminals) to fit behind the mirror - not a switch.

    I have no idea what such a module would be called.


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    #6
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    For the mirror, use what Stoner suggested, it will do what you need.

    For the light and fan, you could put in a PIR sensor and get rid of the switch.


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    #7
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    The mirror might be tricky as fitting a mains connected switch should be outside the bathroom.

    The mirrors often have a little pullchord on them.


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    #8
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    Bruthal wrote: »
    The mirror might be tricky as fitting a mains connected switch should be outside the bathroom.

    The mirrors often have a little pullchord on them.

    Very true, I hadn't considered that.

    Only way around regs there would be a ceiling pullcord with a one-shot timer (and maybe a relay) on it in a box in the ceiling. The mirror would have to be left on with the cord snipped.

    Not ideal and getting expensive.


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    #9
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,757 Mod ✭✭✭✭Sam Russell


    I have a the mirror wired into the light switch and the mirror has LED lights that turn on using a contactless switch. With the central light off the mirror is unpowered, but with the light on, the mirror and LED both power on through the contactless switch. What I want to do is set it that the mirror heater goes out after 10 mins or so, but leaves the LED on. I will then get the mirror powered directly, so that the mirror is independant.

    The device should be wired out of touch and fit behind the mirror - there is quite a bit of room perhaps 1cm or more.


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    #10
    Steve
    Moderators, Category Moderators, Entertainment Moderators, Sports Moderators Posts: 22,584 CMod ✭✭✭✭Steve


    Sam, just to get my head around this, is your concern about the electricity being used because it will be left on? or is this something you just 'want to have'?

    My answer to questions like this is always 'of course it's possible, how much can you spend on it?'

    If it costs more than the electricity it will save then it's not worth it.

    A 250W mirror will cost a bit if left on 24/7 for a year, a fan not so much. Fans are rated for continuous use so it will not burn out if left on for several extra hours a day.

    What you want is possible, I'm not sure you'll fit it into a 1cm gap behind a mirror.


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    #11
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    A modular type timer could be put into the mirror enclosure. When power is switched onto it, it can switch off after a time set on the timer.


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    #12
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 19,757 Mod ✭✭✭✭Sam Russell


    http://www.amazon.co.uk/MXA046-Switch-minutes-Circuit-FutureKit/dp/B019BP18XC/ref=sr_1_40?ie=UTF8&qid=1455564232&sr=8-40&keywords=timer+circuits

    This is what I am looking for but not at this price and preferably in a little box.

    I just want a circuit that will prevent the heater or fan unit being left on unattended. They are built into quite a lot of things and I thought they would be available stand alone. (e.g. security lights)


    Oh well.


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