Subject:
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Re: Basement water alarm
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 3 Feb 2000 21:02:47 GMT
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Viewed:
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1839 times
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In lugnet.robotics, Brian Alano writes:
> Do you mean that my alarm clock follows the 60 Hz carrier? That confuses me--
I'd think it has an accurate crystal oscillator.
> I once programmed my Timex/Sinclair Z80 to be a clock based on the power line
> carrier. It kept terrible time. I assumed it was because of the inaccuracy of
> the carrier.
No, the frame counter in the ZX80/81/Spectrum (if yours is a ZX80 rather
than 81, I'd like to buy it, BTW) simply counts the TV frames it produces.
Those, in turn, would be about 60Hz in the US version, which is due to
the TV frequency, which is apprently due to the mains frequency.
But it does not actually sense the mains frequency. (Proof - you
can run it on a battery, and the picture is not disturbed.)
-gbr
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Message is in Reply To:
 | | Re: Basement water alarm
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| Do you mean that my alarm clock follows the 60 Hz carrier? That confuses me-- I once programmed my Timex/Sinclair Z80 to be a clock based on the power line carrier. It kept terrible time. I assumed it was because of the inaccuracy of the carrier. (...) (25 years ago, 3-Feb-00, to lugnet.robotics)
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