On Fri, 23 Oct 2009 19:05:04 -0400, wrote:

On Fri, 23 Oct 2009 12:02:37 -0400, "rt003119" wrote:

Group.

I need a 24 hour countdown timer such as the CANUK118 - Digital Clock With
Timer (http://www.electronickits.com/kit/co.../canck118.htm). The
additional feature I need is the ability to shut off the timer circuit at
(say 13:00 hours), in advance of the final countdown time of (say 14:00
hours), and have the timer circuit reset automatically to the desired final
countdown time of 14:00 hours, 24 hours later. Said another way, if the
countdown time is set to activate the relay circuit at 14:00 hours and the
timer is disengaged at 13:00 hours, I don't want to have to wait until
14:01 hours to reactivate the timer circuit to avoid the relay from being
activated at 14:00 hours or 60 minuets later.

Can anyone help with this issue? Any help, guidance or referrals will be
appreciated.

Regards,

Bob


So you want an alarm that goes off at a time you want, say 12:30 hours, but if
you hit cancel, it will not go off that day, but the next? I guess it will go
off every day at that time if you don't touch it?

You need a logic latch to kill the alarm until the clock hits midnight, and then
restores it, that's all. You can change the alarm time now because the clock
alarm is "killed" untill midnight.

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I don't think he's asking for a way to change the alarm time, in real
time, since that's easy enough to do with the kit.

What I think he wants is a way to override the alarm from the time the
override was issued and then release the override 24 hours later.
---

If you don't want it to go off every day, but just delay one day, you need
another latch to make sure the alarm only goes once and then kills the "alarm
on" setting.

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As I see it, he only needs one latch which is set when the override is
issued and then reset when the 24 hour timer times out.