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One shot one day segment timer

Discussion in 'General Electronics Discussion' started by flippineck, Apr 14, 2016.

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  1. flippineck

    flippineck

    269
    9
    Sep 8, 2013
    Not sure if anybody makes a timer like this..

    You know those plug-in mains timers that work mechanically, like a 24hr clock face & have a ring of tiny 15-minute segments you can click out for 'on' and in toward the centre for off?

    I'm looking for one that only stores 'on' settings for a day on a rolling basis. i.e. once a segment has passed the switching point, it gets cancelled to 'off' regardless of whether it was on or off beforehand.

    This is to control a central heating system in a house sporadically occupied. So that, when the occupant arrives, he sets up the segments for the next 24 hours to match his expected use. Then, as time passes over the course of the day, his mechanically programmed directions are executed as the clock face moves round.

    When he randomly gets called away and forgets all about the heating, it's okay because after a maximum of 24 hours, that's the end of the 'on' settings and the heating won't come on again until he returns and reprograms more segments.

    Can anyone direct me to a source for something like this? Ideally I like the intuitive simplicity of the mechanical segment design, anybody can understand it with ease. If there's a digital solution out there somewhere that's extremely easy for dimwits to understand that'd be ok though!

    Thanks if anyone can bring anything to mind
     
  2. flippineck

    flippineck

    269
    9
    Sep 8, 2013
    Sorry to double-post but been thinking about this..

    Looking at the wiring for a Y-plan / 3 port valve heating system, I could accomplish what I want without changing or disturbing the two timeclocks currently fitted (one for hot water and one for central heating)

    The central heating timer just interrupts 240VAC - either connected or just open circuit.

    The hot water timer outputs 240VAC on the two throw contacts of one SPDT switch - one is designated 'hot water ON' whilst the other throw is designated 'hot water OFF'.

    The common terminals of the hot water and central heating timer SPDT switches are wired together and to a permanent live 240VAC supply.

    Using a count-down timer with one SPDT switch, I could feed 240VAC to either (a) both common terminals of the existing timers SPDT switches or to (b) just the 'hot water OFF' throw of the hot water timer's SPDT switch.

    This would then mean, if the countdown timer was in one state, heating and hot water programs would be executed as normal, whilst in the other, the system would be signalled to be permanently 'OFF' on both channels.

    The motors of both existing timers would run as normal, and their programs would stay current - just they wouldn't be executed unless countdown timer said they could be.

    So.. looks like I need a countdown timer with the following attributes..

    Mechanical / clockwork / or at least, very very easy to program LCD style
    Maybe even a simple pushbutton design?
    240VAC operation
    Capable of counting down a reasonable delay say, 'press for 24hrs of heating'.
    One full set of SPDT contacts capable of handling a 6W 3 port valve, a central heating pump, and a boiler call signal
    Screw terminals, not plug-in type

    I've been searching online, ebay etc, been finding a few that fill some but not all of the criteria.. as per original post, just want to know if anybody can point me to a supplier for such an animal if anything springs to mind. Thanks.
     
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