When I was growing up (the 1970s, mostly), the standard wall clock had an AC cord sticking out of the bottom and a second hand that moved continuously without clicking. It kept time by relying on the fact that the power company always delivered power at 60 Hz. (Yes, I live in the U.S…) In fact, my dad told me that power companies were required to send out exactly 86,400 x 60 cycles every 24 hours. If for some reason the frequency slipped down to (say) 59.9 Hz for an hour, they’d have to make up for it by cranking the frequency up to 60.1 Hz for an hour afterward.
Now, though, it seems every wall clock I see for sale is battery-powered and uses a quartz movement, in which the second hand ticks forward once per second and doesn’t move in between. Even the very few plug-in wall clocks I can find just use the AC power to run the quartz movement circuitry.
Does anybody still make old-fashioned plug-in clocks that don’t use quartz movement, and that rely on a good old-fashioned 60 Hz AC motor?
In 2011 the US ran a year long experiment to allow power companies to not maintain long term 60Hz on the power grid. The reason given to allow the power companies more flexibility in maintaining the stability of the power grid. Quick googling only shows articles talking about the start of the experiment. I haven’t seen anything saying power companies still run the grid in a way that beaks AC powered clocks.
I will note that quartz crystals are super cheap and it is probably cheaper to make a quartz clock that a clock that runs off of the power grid.
Wow. I remember wind-up clocks. That’s even older old-school than AC. (I had a couple of wind-up alarm clocks, but I would always overwind them. I was afraid of them running down.)
One of my prized possession is my grandfather’s grandfather clock. It was originally purchased in 1911 as a wedding gift for my grandparents to each other. It has weights that you have to crank up once a week. The pendulum actually ticks once a second each way. I used to watch him wind it every Sunday. Now I wind it – though I do so twice a week as I don’t like to wind the weights all the way up.
As an aside, the battery powered clocks don’t have to tick. We had one in the bathroom adjoining the bedroom and it keep me awake some nights. You can get ‘silent’ clocks which do hum a tiny bit, but are much more quiet. However they do go through batteries much quicker.
As an aside, sweep second hands aren’t exclusive to electric clocks. I have a mainspring-movement wristwatch that has a second hand with a continuous sweep.
How does that work? Is it really continuous? I know Rolexes, famous for their “continuous” second hand sweep are actually just beating faster than once per second (I think the newest ones are 8 beats per second?).
It looks continous to my naked eye, but I don’t know anything about watches. Perhaps Si Amigo is right. It makes enough quick, small movements to give the illusion of continuous movement, much like moving pictures. Something to do with the persistence of vision, probably.
Sure. If it’s a quartz watch it could be a very high number of beats per second, but with your mechanical watch, I bet its not higher than a Rolex’s 8.