Over here they use a tone system that is modulated onto the mains to operate a relay to switch over to night rate and turn on the immersion heater in the hot water cylinder.
Steve Rooke 2009/12/29 Rob Kimberley <[email protected]>: > AFIK a lot of the clocks were radio controlled from MSF Rugby (now Anthorn, > Cumbria). You would need to have some sort of automated system to > accommodate daylight savings switchovers in Spring and Autumn. That said, I > would have thought once synchronised, they would "tick" off the 50 Hz > supply. > > Rob Kimberley > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Dr. David Kirkby > Sent: 28 December 2009 23:22 > To: Discussion of precise time and frequency measurement > Subject: [time-nuts] Can a quartz crystal go off by 2% ? > > I'm on the so-called 'Economy 7' electric in the UK, where I'm supposed to > get > cheap electric from 0030 to 0730 - i.e. a 7 hour period when electricity > demand > is low. I'm no longer heating by electric, but do run some computers 24/7. > It's > not totally clear whether this saves me money or costs me money, as I pay a > higher price per unit during the expensive period, to compensate for the > fact I > get it cheap for 7 hours. But I run some computers 24/7. I guess I should do > the > maths and work it out. Apart from some heaters in the garage, which are very > > rarely used, I no longer heat with it. > > The time when the electric is cheap is set by a clock, which rotates > once/day. > It says on it "quartz" somewhere, so it must be regulated by a crystal and > not > from the 50 Hz supply, which would be pretty useless, as the clock would go > wrong if there was ever a power failure. The clock has not been changed in > the > 17 years I've lived at my house, though the meter has on a couple of > occasions. > > The clock used to keep accurate, but now it looses time about 30 > minutes/day. I > wrote a computer program to predict when the electric is cheap, so we can > schedule when things like the washing machine, dishwasher, Hoover etc are > used. > Even cooking to a certain extent, if it's convenient, though our life does > not > revolve around the cheap electric. > > I'm wondering if this is a mechanical fault in the clock, or whether the > crystal > has developed a fault. It's clearly well outside any tolerance or aging > process > of any crystal - even the cheapest ones. > > I've not done any very extensive tests, but the error does not appear to be > constant. Hence every month or so I need to produce a new table, as my > predictions get less accurate with time. Since one can only read the clock > to an > accuracy of about 15 minutes, it's not easy to know how far it is out. > Sometimes > we hear the contactor go over, as this is supposed to then power the storage > > heaters, which we no long use. > > Dave > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Steve Rooke - ZL3TUV & G8KVD A man with one clock knows what time it is; A man with two clocks is never quite sure. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
