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Subject: Re: timer with 12 hr interval
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Date: 11/17/02 at 7:14 PM
Posted by: Brian Snell
In Reply to: timer with 12 hr interval posted by nilesh deshmukh on 10/28/02 at 6:23 AM:
Greetings. Re your 12 hour timing circuit --a CMOS 4060 chip is a ripple counter with 14 stages of binary division to a maximum of divide-by 16,384. The chip also features an internal oscillator capable of being timed by an RC network or a crystal. For a 12 hour interval, a clock rate of around 2.7 seconds would serve with the output being taken from the highest (14) divider output. Depending on what you may require in the form of output, some additional simple logic may be required to "freeze" the clock after the required interval, or whatever. The output signal may be used to turn on a transistor, optocoupler, etc, provided you use a series resistor of around 10K to limit current. I have used this chip on many occasions for odd timing applications and it works reliably. I hope that this helps.
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