'Logic'

[Cursitor Doom]

Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

[Bill Sloman]

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

The battery is usually too close to flat to make an audible noise - CMOS
logic and LCDs usually keeps on working until the battery voltage
collapses, but you can't draw enough current when the battery is close
to end of life to make an audible sound.

The first thing to do when anything battery powered goes wonky is to put
in a new battery. Checking the battery voltages while you are doing that
can be informative.

Piezo-electric speakers can get damaged when you drop the device, even
the though the shock isn't big enough to damage the rest of the electronics.

With a mechanical alarms you can see any damage. Modern stuff isn't
quite as easy to inspect.

[Cursitor Doom]

Post by Bill Sloman

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

The battery is usually too close to flat to make an audible noise - CMOS
logic and LCDs usually keeps on working until the battery voltage
collapses, but you can't draw enough current when the battery is close
to end of life to make an audible sound.
The first thing to do when anything battery powered goes wonky is to put
in a new battery. Checking the battery voltages while you are doing that
can be informative.
Piezo-electric speakers can get damaged when you drop the device, even
the though the shock isn't big enough to damage the rest of the electronics.
With a mechanical alarms you can see any damage. Modern stuff isn't
quite as easy to inspect.

I'm afraid I've still had alarms fail when none of the above possible
causes applies.

[Bill Sloman]

Post by Cursitor Doom

Post by Bill Sloman

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

The battery is usually too close to flat to make an audible noise - CMOS
logic and LCDs usually keeps on working until the battery voltage
collapses, but you can't draw enough current when the battery is close
to end of life to make an audible sound.
The first thing to do when anything battery powered goes wonky is to put
in a new battery. Checking the battery voltages while you are doing that
can be informative.
Piezo-electric speakers can get damaged when you drop the device, even
the though the shock isn't big enough to damage the rest of the electronics.
With a mechanical alarms you can see any damage. Modern stuff isn't
quite as easy to inspect.

I'm afraid I've still had alarms fail when none of the above possible
causes applies.

I listed the most likely failure modes. Your judgement about what caused
your alarm to fail isn't going to be all that reliable - which is
presumably why you asked the question.

I've currently got an electronic alarm clock that doesn't work - the
problem that caused me to take it apart was that the press-button
control contacts had stopped working. The ultra hook-up wire that
connected the electronics to the battery broke off in the dismantling
process, and the wire is too thin to let me solder it back on. I've got
a reel of heavier insulated hook-up wire around somewhere, but I haven't
found it yet (nor looked very hard - I've got several electronic alarm
clocks and most of them work, and all the others keep good time).

[John Larkin]

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

Because they probably run Linux and have a million lines of code.

[Cursitor Doom]

Post by John Larkin

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

Because they probably run Linux and have a million lines of code.

Sorry, John, but I can't have Linux maligned. AFA stability is
concerned, it's always been *way* more solid than Windows. It's
Windows that has millions of lines of code and thousands of bugs, not
Linux.

[John Larkin]

Post by Cursitor Doom

Post by John Larkin

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

Because they probably run Linux and have a million lines of code.

Sorry, John, but I can't have Linux maligned. AFA stability is
concerned, it's always been *way* more solid than Windows. It's
Windows that has millions of lines of code and thousands of bugs, not
Linux.

Using a giant OS for a simple application is dangerous. Tasks,
threads, pipes, callbacks, queues, wrappers, daemons, semaphores,
mutexes, abstraction are all great fun, when the application itself is
boring.

[Bill Sloman]

Post by John Larkin

Post by Cursitor Doom

Post by John Larkin

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

Because they probably run Linux and have a million lines of code.

Sorry, John, but I can't have Linux maligned. AFA stability is
concerned, it's always been *way* more solid than Windows. It's
Windows that has millions of lines of code and thousands of bugs, not
Linux.

Using a giant OS for a simple application is dangerous. Tasks,
threads, pipes, callbacks, queues, wrappers, daemons, semaphores,
mutexes, abstraction are all great fun, when the application itself is
boring.

This rather misses the point that that application itself is extremely
undemanding, and is almost certainly handled by a single
application-specific integrated circuit. You'd design it using Verilog
or VHDL, if you were starting from scratch, which nobody in the industry
would be.

About the only interesting are in the design would be user interface,
and Linux wouldn't help there.

Linux wouldn't come into it.

[Bill Sloman]

Post by John Larkin

Post by Cursitor Doom
Why is it sometimes digital alarms sometimes don't go off? Every once
in a while, you find that when they reach the appointed hour, they
simply remain silent. The old-style 'bell & ringer' mechanical alarm
clocks never failed AFAICR. Why do electronic ones sometimes do so?

Because they probably run Linux and have a million lines of code.

That has to be the silliest post I've ever seen. Who would put enough
memory into a alarm clock to hold a million lines of code? There are few
more demented implications in there, but why waste bandwidth on spelling
them out?