Power Cut Puzzle.

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TES

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Afternoon all,

Bit of a light hearted one.

I was asked an electrical question today that I couldn't give an answer to (hate when that happens) yet. It was that they have alarm clocks either side of the bed plugged into separate sockets and when they have a very brief power dip only one alarm will reset to 12:00 and the other one wont but it will happen to both just not at the same time.

You would think that if there were to be an issue as such it would be with the circuit, however she then said that the cooker will do it as well but not the clocks.

Any thoughts or am I having one of my thick moments?

Cheers.

Tes.

 
Power supplies and capacitors.

It all depends how long the DC power supply inside the units holds up for before dipping below a critical voltage.

We have the same, my (very old) clock radio the display will go out near instantly when the power goes off, and come back on "reset"  SWMBO's much newer LCD screen clock radio will hold up for several seconds before the display goes out, and remember the correct time for a few seconds after the display has gone out.

 
That's one thing I forgot to ask was if they were different clocks and the age.

The cooker was a bit of a curveball in my thinking and with both clocks doing it but then that will come down to how long the power was off.

You know how it is when your asked a question and they stand there watching your brain tick while adding the the question and expecting a solid explanation.

Thanks for your replies,

Tes.

 
I used to have a bedside clock with a 9v "standby battery" in it. It was only to keep the time right when there was a powercut, it did not run the display in a powercut.

 
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