One of the good things, or perhaps the worst thing (it depends on where
and when) about my job is I travel a bit.  One of the more interesting
places (again in both good and bad ways) was Port Moresby,
Papua New Guinea. Lots of stuff doesn’t work too well over there. It’s
hard to get experience maintenance staff, its hard to get the right
parts over there and probably the hardest part is paying for it. 

was always surprised the clocks never work right. They are either
horribly fast or slow.  At first I thought the hotel had just not set
it right, so I set it to the right time. But the next morning it was
out again. What the hell was going on?

Most alarm clocks work
off the power. In both Australia and PNG this is 50Hz, so the clock
rectifies the AC power coming in to get 50 pulses a second. Count 50
pulses and you have a second, do this 60 times and tick over a minute.

take for granted that the frquency of power is right on 50Hz, but
talking with the students who were doing power engineering it is
actually quite hard to do. It’s like having a car with the same revs no
matter if you are going up or down a hill.

Anyhow, if you need
to wake up the right time in PNG, use the alarm clock on your phone.
Otherwise you may be jumping out of bed at 5am thinking you are running
late, then wondering where the sun went.

Comments (5)

  1. patrakov

    I am surprised that this practice (relying on the mains frequency) still exists. Even in 1980, the use of quartz resonators was common in Russian clocks.

  2. Craig

    I did think of that, but I was there 3 times in 3 different rooms and it happened to me and a few others. I do recall pulling a clock-radio apart years ago and saw they took the pulse off the diodes which was different link to the main power and the smoothing capacitors. The only thing I can think of is they save a few cents not using a crystal and these were cheap and nasty alarm clocks.


    Perhaps they’re using American clocks (designed for 60hz AC). How long does it take for the clock to be noticably wrong?

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