Long Interval Clock and/or Timer Needed

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WildBoar
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Long Interval Clock and/or Timer Needed

Post by WildBoar » Fri Jun 04, 2004 11:28 am

I've got a large fence around my backyard.
The gate is always locked for security
reasons. Before the fence was erected
the person who came approximately once
a month to read my power meter had no
problems accessing the meter. Now, I
have to leave notes all over the house
reminding everyone to unlock the gate
the night before the meter reader guy
is expected. The date is listed on the
bill. About half the time someone remembers
to unlock the gate.<p>I need a dedicated clock or timer that can
be set to go off after 25-to-35 days have
elapsed. The alarm must keep repeating
until someone physically shuts it off.
Obviously, this last feature is important
because if the alarm ceases after a few
cycles and no one is home to hear it won't
be of much help.<p>I'm aware that there are hundreds (if not
thousands) of applets that you can install
on your PC that will remind you of anything
based on a particular date or time. That
would be fine if I used my PC seven days
a week. I don't.<p>WildBoar

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haklesup
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Re: Long Interval Clock and/or Timer Needed

Post by haklesup » Fri Jun 04, 2004 11:41 am

A cheap PDA would have the calendar alarm function you need. I've seen the Palm III's going relatively cheap lately and toy-like models going for practically nothing. Not sure about the sustained alarm mode though because I don't own one.<p>You could tape it to the fridge and use it to remind you of other things as well. Could probably program the whole year in advance. I understand there are loads of programs for the PDA's out there and some might be just the enhancement you want.

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Chris Smith
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Re: Long Interval Clock and/or Timer Needed

Post by Chris Smith » Fri Jun 04, 2004 1:16 pm

The 555 can be set for up to 400 hours at a time, or 16 days, and a simple counter of say three, can count eight day intervals or 10 ...3 day, etc.<p>I think the 4017 counts by ten, then latches. Set the 555 for X days, times ten and then latch. Very simple to build.

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jwax
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Re: Long Interval Clock and/or Timer Needed

Post by jwax » Fri Jun 04, 2004 3:23 pm

If you want still another idea, use a photocell/phototransistor to count day/night cycles. Alarm sounds when the preset number of days equals the day cycle count.
John

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MrAl
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Re: Long Interval Clock and/or Timer Needed

Post by MrAl » Fri Jun 04, 2004 7:36 pm

Hello there,<p>Give the guy a key :-)<p>Seriously, a more advanced electronic lock
may allow multiple combinations with logging.
You could give him a special combination.
When he uses it, it gets logged so you know
what day he came. No one else should have
that key combination.<p>Simpler would be a combination lock with
a security camera that turns on when the
gate opens.<p>Take care,
Al
LEDs vs Bulbs, LEDs are winning.

JavaBen
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Re: Long Interval Clock and/or Timer Needed

Post by JavaBen » Sat Jun 05, 2004 7:43 am

Yea, that's a good idea - something along those lines is a 'Lock Box' similar to the one that Realtors use on houses that are for sale. Ace Hardware sells them for general use (we have one for the cleaning service that comes to our house) at around $20. They let you change the code to whatever you want, whenever you want. It also comes in handy if you lock yourself out!
Ben Bailey
Alpharetta, GA

WildBoar
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Re: Long Interval Clock and/or Timer Needed

Post by WildBoar » Sat Jun 05, 2004 11:54 am

WOW!<p>Thanks to all you guys for your replies.<p>Some of the ideas mentioned above crossed
my fuzzy brain. Buying a cheap PDA or building
a timing box of some sort were a couple of
things I did contemplate.<p>Years ago, when I first got into breadboarding
and building electronic gizmos my favorite type
of project usually involved some kind of complex
timing circuitry.<p>As I got older and complex electronic devices
got cheaper my enthusiasm for designing, bread-
boarding, and building these sorts of things
faded.<p>Maybe I will sit down at the old breadboard,
blow off the dust and start plugging in
components. If I have a couple of stiff drinks
before I start I might even convince myself
that I'm having fun!<p>WildBoar

josmith
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Re: Long Interval Clock and/or Timer Needed

Post by josmith » Sat Jun 05, 2004 12:11 pm

If you have an old vcr you could program it to the date of the reading and use the record light to trigger your alarm.

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