Automatic countdown reset timer?
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From: BoyntonStu on 7 Jul 2010 22:33 Problem: Sense a person in a room. Trigger a countdown timer that is preset to a fixed time when a person is sensed. (A motion detector or a beam breaker is acceptable) The timer will control a 110 VAC device that is normally off. If a different sensor is triggered elsewhere in the house within the countdown period, reset the timer to the original preset time. Suggestions?
From: Jasen Betts on 8 Jul 2010 05:19 On 2010-07-08, BoyntonStu <boyntonstu(a)gmail.com> wrote: > Problem: > > Sense a person in a room. > > Trigger a countdown timer that is preset to a fixed time when a person > is sensed. > > (A motion detector or a beam breaker is acceptable) > > The timer will control a 110 VAC device that is normally off. > > If a different sensor is triggered elsewhere in the house within the > countdown period, reset the timer to the original preset time. > > Suggestions? seems kind of vague, what's the meaning of "reset" and "trigger" what sort of precision and approximate magnitude for the timer. --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: default on 8 Jul 2010 08:07 On Wed, 7 Jul 2010 19:33:48 -0700 (PDT), BoyntonStu <boyntonstu(a)gmail.com> wrote: >Problem: > >Sense a person in a room. > >Trigger a countdown timer that is preset to a fixed time when a person >is sensed. > >(A motion detector or a beam breaker is acceptable) > >The timer will control a 110 VAC device that is normally off. > >If a different sensor is triggered elsewhere in the house within the >countdown period, reset the timer to the original preset time. > >Suggestions? Sounds like you already have a pretty good idea of what you are doing or want to do. A single 555 monostable triggered by an inexpensive off-the-shelf motion detector with an external reset. But you are probably leaving something out - like what precision do you want, and does time need to be adjusted with some degree of accuracy and will it change often, how user-friendly, etc.. --
From: BoyntonStu on 8 Jul 2010 08:54 On Jul 8, 8:07 am, default <defa...(a)defaulter.net> wrote: > On Wed, 7 Jul 2010 19:33:48 -0700 (PDT), BoyntonStu > > > > <boynton...(a)gmail.com> wrote: > >Problem: > > >Sense a person in a room. > > >Trigger a countdown timer that is preset to a fixed time when a person > >is sensed. > > >(A motion detector or a beam breaker is acceptable) > > >The timer will control a 110 VAC device that is normally off. > > >If a different sensor is triggered elsewhere in the house within the > >countdown period, reset the timer to the original preset time. > > >Suggestions? > > Sounds like you already have a pretty good idea of what you are doing > or want to do. > > A single 555 monostable triggered by an inexpensive off-the-shelf > motion detector with an external reset. > > But you are probably leaving something out - like what precision do > you want, and does time need to be adjusted with some degree of > accuracy and will it change often, how user-friendly, etc.. > -- 5 minute time accuracy is fine. You walk into a room, the motion detector sees you and it sends a signal to the timer/controller which activates a 5 Amp 110 Vac circuit for let's say 45 minutes.. If you walk around the room and the sensor sees you again within the 45 minutes; nothing happens. Only after the timer counts down will that room sensor reset the timer.. However, If you, or another person goes into another room and its sensor detects movement withing the 45 minute countdown, the timer/ controller resets to 45 minutes. Is this clear?
From: BoyntonStu on 8 Jul 2010 10:02
On Jul 8, 8:54 am, BoyntonStu <boynton...(a)gmail.com> wrote: > On Jul 8, 8:07 am, default <defa...(a)defaulter.net> wrote: > > > > > On Wed, 7 Jul 2010 19:33:48 -0700 (PDT), BoyntonStu > > > <boynton...(a)gmail.com> wrote: > > >Problem: > > > >Sense a person in a room. > > > >Trigger a countdown timer that is preset to a fixed time when a person > > >is sensed. > > > >(A motion detector or a beam breaker is acceptable) > > > >The timer will control a 110 VAC device that is normally off. > > > >If a different sensor is triggered elsewhere in the house within the > > >countdown period, reset the timer to the original preset time. > > > >Suggestions? > > > Sounds like you already have a pretty good idea of what you are doing > > or want to do. > > > A single 555 monostable triggered by an inexpensive off-the-shelf > > motion detector with an external reset. > > > But you are probably leaving something out - like what precision do > > you want, and does time need to be adjusted with some degree of > > accuracy and will it change often, how user-friendly, etc.. > > -- > > 5 minute time accuracy is fine. > > You walk into a room, the motion detector sees you and it sends a > signal to the timer/controller which activates a 5 Amp 110 Vac circuit > for let's say 45 minutes.. > > If you walk around the room and the sensor sees you again within the > 45 minutes; nothing happens. > > Only after the timer counts down will that room sensor reset the > timer.. > > However, If you, or another person goes into another room and its > sensor detects movement withing the 45 minute countdown, the timer/ > controller resets to 45 minutes. > > Is this clear? Perhaps I made it too complicated. All sensor signals will set the timer to 45 minutes. IOW After the last sensor detects motion and signals the timer, it will count down 45 minutes. That would make it much simpler. |