5 ms·

Debugging my wife's alarm clock

137 points by zdw 2y ago

deleted 2y ago
[deleted]
pryelluw 2y ago
Weirdly I ran into something similar many years ago. I took a similar alarm clock and hacked it to connect it the alarm signal to a stereo system with two 12 inch subwoofers. It was very very very loud. Neighbors could hear it a street over. Anyhow, I had to update how it powered the internal speaker (which I was taping into) because it was a little bit too much and the thing would reset. I’d go into more details but it was trashed and it’s been about 20 years since …
- garbagewoman 2y ago
  [flagged]
- sigseg1v 2y ago
  I'd love an alarm clock that can replicate the sounds of my teenage youth via playing classics such as "Extreme Mario Dubstep - Yoshi Bass Drop (Womp Womp Edition Remix)"
  - pryelluw 2y ago
    That shouldn’t be too hard these days. You can go the expensive route and use a raspberry pi but I know you can use something simpler. You can def do it for cheaper but an RPi does allow you internet connectivity and a buttload of other possible automations. Hell, add a zwave adapter and you can have the alarm flash your smart lights, and more!
ajb 2y ago
I've got a label printer that uses a battery because it needs more current than (pre-pd) USB, but needing a battery when you also have AC seems a poor design. Especially a non rechargeable one.
- mongol 2y ago
  The battery keeps the time so it does not reset the time at intermittent power outage
  - ajb 2y ago
    Yeah that's what happens in a normal alarm clock. The OP thinks the design of this one is broken, hence my comment. But some other commenters seem to have a good theory that it's a failure in a component
teruakohatu 2y ago
I am not sure I have ever owned more than one desktop alarm clock, but I have used a few, and in my experience by the time a real power failure occurs the 9v backup batteries have drained to the point that it resets anyway. I have also lived in a country where blackouts quite rare, usually just local blackouts due to a tree hitting a powerline, so in any given year I wouldn't expect one.
poopsmithe 2y ago
I had one of these clocks in the past. I remember the clock working without a battery at all. The battery is only necessary if you want to unplug the clock and move it somewhere else without having to reprogram the time.
- Gare 2y ago
  Or if the power goes out. Where I live, there are at least several outages per year.
  - sgt 2y ago
    Most places in the world that are slightly more exposed to weather than average run the risk of power outages. That'll be anywhere from Norway to Texas to Australia. In other parts of the world blackouts may be enriched by lack of grid capacity or incompetence.
    - diggan 2y ago
      > Most places in the world that are slightly more exposed to weather than average run the risk of power outages Heavily depends on how exposed the infrastructure is, I'd say. I currently live in Spain and been experiencing way more power outages than in Sweden, where I was born and raised, even though the weather is much more extreme in Sweden. Main difference, as far as I can tell, is that Sweden mostly digs trenches for all sorts of cables and infrastructure, while Spain tends to (still) hang cables in the air and on the outside of walls. I still get my fiber from a cable that comes hanging down from the front-side balcony of my flat here in Barcelona, and that's the official installation from my ISP.
      - gutt3r_punk 2y ago
        I had the same experience when I lived in Germany back in the 80/90s. All the infrastructure was underground so the only time we had a power outage was when someone was digging and hit the line. I always bring this up now days living in Georgia where a strong wind can knock out power for a few hours.
winrid 2y ago
Probably the transformer is bad or maybe a cap dried up, so it's just barely running on wall power.
- sebazzz 2y ago
  Caps dry out but transformers don’t go bad unless dropped or something like that.
  - greatartiste 2y ago
    Sometimes if they get to hot or following many many heating/cooling cycles the insulation varnish on the transformer windings starts to fail leading to short circuit issues.
  - winrid 2y ago
    The varnish can wear down, but yes likely a cap
- actionfromafar 2y ago
  This
avidiax 2y ago
> This isn't reproducible by removing the battery entirely, either. If you take it out, the clock loses all ability to function and just resets constantly. So having a mostly drained battery seems to be doing a little work so that it resets once but then resumes normal functioning (until the next time it tries to go off). I think what this really suggests is that the transformer and power supply are providing multiple voltages. The +9V rail is broken, but the other rail (maybe +5V) for the LED display is fine. So the alarm chip and the alarm sounder is running only from the 9V battery. If the battery is weak, then the sudden power demand from sounding the alarm is too much, the voltage dips and the chip resets.
- 05 2y ago
  > I think what this really suggests is that the transformer and power supply are providing multiple voltages. The +9V rail is broken, but the other rail (maybe +5V) for the LED display is fine. There's a reference design in the LM8560N IC PDF that suggests that the additional secondary winding is only used to drive the display, and all other electronics is powered off the main rail. The 10V cap is kaput and it can't filter the input power, 9V just acts as a filter (even a discharged one). The OP should replace the cap with a 16V one, because a 10V cap on a 9V rail just isn't right..
walthamstow 2y ago
Can I get a straw poll on people who still use a dedicated alarm clock? I was born 1990±2, but I have always been an old soul. I've been waking up to BBC Radio 4 since I was a teenager. My current one used to belong to my dad, it's a Sony dream machine with FM/AM, circa 2002.
- averageRoyalty 2y ago
  I've been trying to find one that isn't full of ESP chips or phone chargers for a while, or at least one with a nice flashable chipset. They seem pretty rare these days.
  - andai 2y ago
    The first half of your comment implies a design from the 70s (which is my preference), but the second half contradicts that and is beyond my understanding. If you flashed an alarm clock, what would you make it do?
    - averageRoyalty 2y ago
      The aesthetics and functionality are key for me. I like the 70s style, I don't like the invasive elements of modern tech. I do like them however when I have full control over them. > If you flashed an alarm clock, what would you make it do? No idea, but it might be fun to get it to pick a random global streaming radio station, keep its time in sync via NTP, set it remotely from another device, use it as a remote key for a safe or door, etc. When you control the tech, the limits are whatever you set.
  - tripper_27 2y ago
    Not too hard to build your own. Lots of tutorials based on i.e. ESP32 chips, various blinky light options. Google "Adafruit clock" to get started.
    - averageRoyalty 2y ago
      Thank you. I'll take a look!
andai 2y ago
Fascinating. I thought mains frequency was variable, which is why mains hum can be used to date recordings? It seems that there's some drift (why?) but they try to keep the average constant, over some window? The article mentions the device prefers to use the mains frequency for timekeeping, using the crystal oscillator only as a fallback. I found this surprising, but I don't know much about either of those things.
- shultays 2y ago
  I am no expert but from what I read & remember: it can have fluctuations and lagging behind or leading "real" time but it gets corrected and synchronized back later
phil_k 2y ago
That's intriguing! I was under the impression that the mains frequency varied, which is why mains hum is useful for dating recordings. It appears there is some drift (but why?), although they aim to keep the average stable over a certain period. The article states that the device primarily relies on mains frequency for timekeeping, using the crystal oscillator as a backup. I found that unexpected, though I'm not well-versed in either topic.
- ipieter 2y ago
  The mains frequency is literally how fast the generators in power plants are turning. If the load on the grid increases, those generators slow down slightly and more natural gas/coal/heat needs to be added to increase the frequency again. This whole process is quite complicated as not every plant can react in the same time. Some plants are always at 100% capacity, while others are dedicated to governing the frequency. So there are small fluctuations, often between 0.2 Hz around the base frequency, but the average is very close to the theoretical 50/60 Hz. And for an alarm clock that is good enough.
  - Tempest1981 2y ago
    A while back, this happened in the US: The North American Electric Reliability Corporation (NERC) discussed a proposed experiment that would relax frequency regulation requirements. https://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202%20of%20BARC%20%20BAL004%20DL/BAL-004-0_White_Paper_Clean_09242015.pdf https://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202... Was that made permanent, or reverted? I thought I've noticed the accuracy of my older line clock being worse... trending fast. From https://en.wikipedia.org/wiki/Utility_frequency#US_regulations https://en.wikipedia.org/wiki/Utility_frequency#US_regulatio...
mmastrac 2y ago
Older wall clocks used synchronous motors which would literally move the second hand using the waveform from the A/C power. As loads on generators went up, the effective RPMs went down, causing downstream power to run at slightly slower than 60Hz. It was so heavily used that power stations used to run "fast" catch up on any cycles they fell behind at night so that there were exactly 86,400 in a 24h period to prevent clocks from running fast or slow. Amusingly you'll see stories like this when power companies fail to maintain 60Hz on average over a day: https://www.reddit.com/r/explainlikeimfive/comments/xscztp/eli5_how_can_electric_company_maintenance_affect/ https://www.reddit.com/r/explainlikeimfive/comments/xscztp/e...
- OptionOfT 2y ago
  I remember this happening in Belgium, where they detected it quite like a month after the fact. Everybody got a letter in the mail (yes, snail mail!) explaining when they were going to run the system fast for a couple of hours to catch up.
- userbinator 2y ago
  These were very common in the last century and many continue to be used today: https://en.wikipedia.org/wiki/Telechron https://en.wikipedia.org/wiki/Telechron
- ajb 2y ago
  It may not be used so much for clocks now, but you can still buy cheap timed power switches that use this method. For example: https://www.argos.co.uk/product/5440524 https://www.argos.co.uk/product/5440524
- rob74 2y ago
  Wall clocks use batteries nowadays, but some clocks in devices permanently connected to mains power still use its frequency - e.g. my Siemens kitchen oven, which promptly was off when there were some synchronization issues in the EU grid a few years ago. You'd think that in an appliance that costs several hundred euros, a quartz crystal wouldn't really move the cost needle, but as long as they can get away with it most of the time, why spend more money?
userbinator 2y ago
Update 10/27: A few readers have pointed out to me that it's likely a bad capacitor, which cap it is, and how to test that and/or fix it! When troubleshooting old electronics, rule #1 is "check the caps". Electrolytic capacitors are the most common failure item in solid-state devices. This alarm clock predates the infamous capacitor plague but the finite and somewhat short lifespan of electrolytics has been known since their invention.
- gus_massa 2y ago
  > which cap it is One of my led wall lamp died. I opened the driver/transformer and has a very suspictious capacitor with a curved top. Anyway, I just bought a $3 driver replacement in front of my home. (I'm bad at soldering, so I'd probably need a whole afternoon to try to fix it).
FridayoLeary 2y ago
I had no idea that digital clocks time themselves by by measuring the mains frequency. And that this is an intended, albeit very minor, function of the power grid! It's amazing how things that provide only a tiny benefit to any individual but has an effect on such a massive scale that people actually sit down and spend time making it work.
rob74 2y ago
"Over a decade old" is technically true, but probably an understatement, to me it looks like something from the 1980s or maybe 90s? Apparently it's old enough to not have "planned obsolescence" designed in...
- xnorswap 2y ago
  You can see a "11/99 T1" sticker on the case, which might indicate a batch date of Nov 1999. The printing style on the sticker on the case feels later than 1980s too.
  - rob74 2y ago
    Ok, then maybe it's a model designed in the 80s/early 90s that was still being built in 1999?
- deleted 2y ago
  [deleted]

137 points by zdw 2y ago

deleted 2y ago

[deleted]

Weirdly I ran into something similar many years ago. I took a similar alarm clock and hacked it to connect it the alarm signal to a stereo system with two 12 inch subwoofers. It was very very very loud. Neighbors could hear it a street over. Anyhow, I had to update how it powered the internal speaker (which I was taping into) because it was a little bit too much and the thing would reset. I’d go into more details but it was trashed and it’s been about 20 years since …

garbagewoman 2y ago
[flagged]
sigseg1v 2y ago
I'd love an alarm clock that can replicate the sounds of my teenage youth via playing classics such as "Extreme Mario Dubstep - Yoshi Bass Drop (Womp Womp Edition Remix)"
- pryelluw 2y ago
  That shouldn’t be too hard these days. You can go the expensive route and use a raspberry pi but I know you can use something simpler. You can def do it for cheaper but an RPi does allow you internet connectivity and a buttload of other possible automations. Hell, add a zwave adapter and you can have the alarm flash your smart lights, and more!

ajb 2y ago

I've got a label printer that uses a battery because it needs more current than (pre-pd) USB, but needing a battery when you also have AC seems a poor design. Especially a non rechargeable one.

mongol 2y ago
The battery keeps the time so it does not reset the time at intermittent power outage
- ajb 2y ago
  Yeah that's what happens in a normal alarm clock. The OP thinks the design of this one is broken, hence my comment. But some other commenters seem to have a good theory that it's a failure in a component

teruakohatu 2y ago

I am not sure I have ever owned more than one desktop alarm clock, but I have used a few, and in my experience by the time a real power failure occurs the 9v backup batteries have drained to the point that it resets anyway. I have also lived in a country where blackouts quite rare, usually just local blackouts due to a tree hitting a powerline, so in any given year I wouldn't expect one.

poopsmithe 2y ago

I had one of these clocks in the past. I remember the clock working without a battery at all. The battery is only necessary if you want to unplug the clock and move it somewhere else without having to reprogram the time.

Gare 2y ago
Or if the power goes out. Where I live, there are at least several outages per year.
- sgt 2y ago
  Most places in the world that are slightly more exposed to weather than average run the risk of power outages. That'll be anywhere from Norway to Texas to Australia. In other parts of the world blackouts may be enriched by lack of grid capacity or incompetence.
  - diggan 2y ago
    > Most places in the world that are slightly more exposed to weather than average run the risk of power outages Heavily depends on how exposed the infrastructure is, I'd say. I currently live in Spain and been experiencing way more power outages than in Sweden, where I was born and raised, even though the weather is much more extreme in Sweden. Main difference, as far as I can tell, is that Sweden mostly digs trenches for all sorts of cables and infrastructure, while Spain tends to (still) hang cables in the air and on the outside of walls. I still get my fiber from a cable that comes hanging down from the front-side balcony of my flat here in Barcelona, and that's the official installation from my ISP.
    - gutt3r_punk 2y ago
      I had the same experience when I lived in Germany back in the 80/90s. All the infrastructure was underground so the only time we had a power outage was when someone was digging and hit the line. I always bring this up now days living in Georgia where a strong wind can knock out power for a few hours.

winrid 2y ago

Probably the transformer is bad or maybe a cap dried up, so it's just barely running on wall power.

sebazzz 2y ago
Caps dry out but transformers don’t go bad unless dropped or something like that.
- greatartiste 2y ago
  Sometimes if they get to hot or following many many heating/cooling cycles the insulation varnish on the transformer windings starts to fail leading to short circuit issues.
- winrid 2y ago
  The varnish can wear down, but yes likely a cap
actionfromafar 2y ago
This

avidiax 2y ago

> This isn't reproducible by removing the battery entirely, either. If you take it out, the clock loses all ability to function and just resets constantly. So having a mostly drained battery seems to be doing a little work so that it resets once but then resumes normal functioning (until the next time it tries to go off). I think what this really suggests is that the transformer and power supply are providing multiple voltages. The +9V rail is broken, but the other rail (maybe +5V) for the LED display is fine. So the alarm chip and the alarm sounder is running only from the 9V battery. If the battery is weak, then the sudden power demand from sounding the alarm is too much, the voltage dips and the chip resets.

05 2y ago
> I think what this really suggests is that the transformer and power supply are providing multiple voltages. The +9V rail is broken, but the other rail (maybe +5V) for the LED display is fine. There's a reference design in the LM8560N IC PDF that suggests that the additional secondary winding is only used to drive the display, and all other electronics is powered off the main rail. The 10V cap is kaput and it can't filter the input power, 9V just acts as a filter (even a discharged one). The OP should replace the cap with a 16V one, because a 10V cap on a 9V rail just isn't right..

walthamstow 2y ago

Can I get a straw poll on people who still use a dedicated alarm clock? I was born 1990±2, but I have always been an old soul. I've been waking up to BBC Radio 4 since I was a teenager. My current one used to belong to my dad, it's a Sony dream machine with FM/AM, circa 2002.

averageRoyalty 2y ago
I've been trying to find one that isn't full of ESP chips or phone chargers for a while, or at least one with a nice flashable chipset. They seem pretty rare these days.
- andai 2y ago
  The first half of your comment implies a design from the 70s (which is my preference), but the second half contradicts that and is beyond my understanding. If you flashed an alarm clock, what would you make it do?
  - averageRoyalty 2y ago
    The aesthetics and functionality are key for me. I like the 70s style, I don't like the invasive elements of modern tech. I do like them however when I have full control over them. > If you flashed an alarm clock, what would you make it do? No idea, but it might be fun to get it to pick a random global streaming radio station, keep its time in sync via NTP, set it remotely from another device, use it as a remote key for a safe or door, etc. When you control the tech, the limits are whatever you set.
- tripper_27 2y ago
  Not too hard to build your own. Lots of tutorials based on i.e. ESP32 chips, various blinky light options. Google "Adafruit clock" to get started.
  - averageRoyalty 2y ago
    Thank you. I'll take a look!

andai 2y ago

Fascinating. I thought mains frequency was variable, which is why mains hum can be used to date recordings? It seems that there's some drift (why?) but they try to keep the average constant, over some window? The article mentions the device prefers to use the mains frequency for timekeeping, using the crystal oscillator only as a fallback. I found this surprising, but I don't know much about either of those things.

shultays 2y ago
I am no expert but from what I read & remember: it can have fluctuations and lagging behind or leading "real" time but it gets corrected and synchronized back later

phil_k 2y ago

That's intriguing! I was under the impression that the mains frequency varied, which is why mains hum is useful for dating recordings. It appears there is some drift (but why?), although they aim to keep the average stable over a certain period. The article states that the device primarily relies on mains frequency for timekeeping, using the crystal oscillator as a backup. I found that unexpected, though I'm not well-versed in either topic.

ipieter 2y ago
The mains frequency is literally how fast the generators in power plants are turning. If the load on the grid increases, those generators slow down slightly and more natural gas/coal/heat needs to be added to increase the frequency again. This whole process is quite complicated as not every plant can react in the same time. Some plants are always at 100% capacity, while others are dedicated to governing the frequency. So there are small fluctuations, often between 0.2 Hz around the base frequency, but the average is very close to the theoretical 50/60 Hz. And for an alarm clock that is good enough.
- Tempest1981 2y ago
  A while back, this happened in the US: The North American Electric Reliability Corporation (NERC) discussed a proposed experiment that would relax frequency regulation requirements. https://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202%20of%20BARC%20%20BAL004%20DL/BAL-004-0_White_Paper_Clean_09242015.pdf https://www.nerc.com/pa/Stand/Project%2020101422%20Phase%202... Was that made permanent, or reverted? I thought I've noticed the accuracy of my older line clock being worse... trending fast. From https://en.wikipedia.org/wiki/Utility_frequency#US_regulations https://en.wikipedia.org/wiki/Utility_frequency#US_regulatio...

mmastrac 2y ago

Older wall clocks used synchronous motors which would literally move the second hand using the waveform from the A/C power. As loads on generators went up, the effective RPMs went down, causing downstream power to run at slightly slower than 60Hz. It was so heavily used that power stations used to run "fast" catch up on any cycles they fell behind at night so that there were exactly 86,400 in a 24h period to prevent clocks from running fast or slow. Amusingly you'll see stories like this when power companies fail to maintain 60Hz on average over a day: https://www.reddit.com/r/explainlikeimfive/comments/xscztp/eli5_how_can_electric_company_maintenance_affect/ https://www.reddit.com/r/explainlikeimfive/comments/xscztp/e...

OptionOfT 2y ago
I remember this happening in Belgium, where they detected it quite like a month after the fact. Everybody got a letter in the mail (yes, snail mail!) explaining when they were going to run the system fast for a couple of hours to catch up.
userbinator 2y ago
These were very common in the last century and many continue to be used today: https://en.wikipedia.org/wiki/Telechron https://en.wikipedia.org/wiki/Telechron
ajb 2y ago
It may not be used so much for clocks now, but you can still buy cheap timed power switches that use this method. For example: https://www.argos.co.uk/product/5440524 https://www.argos.co.uk/product/5440524
rob74 2y ago
Wall clocks use batteries nowadays, but some clocks in devices permanently connected to mains power still use its frequency - e.g. my Siemens kitchen oven, which promptly was off when there were some synchronization issues in the EU grid a few years ago. You'd think that in an appliance that costs several hundred euros, a quartz crystal wouldn't really move the cost needle, but as long as they can get away with it most of the time, why spend more money?

userbinator 2y ago

Update 10/27: A few readers have pointed out to me that it's likely a bad capacitor, which cap it is, and how to test that and/or fix it! When troubleshooting old electronics, rule #1 is "check the caps". Electrolytic capacitors are the most common failure item in solid-state devices. This alarm clock predates the infamous capacitor plague but the finite and somewhat short lifespan of electrolytics has been known since their invention.

gus_massa 2y ago
> which cap it is One of my led wall lamp died. I opened the driver/transformer and has a very suspictious capacitor with a curved top. Anyway, I just bought a $3 driver replacement in front of my home. (I'm bad at soldering, so I'd probably need a whole afternoon to try to fix it).

FridayoLeary 2y ago

I had no idea that digital clocks time themselves by by measuring the mains frequency. And that this is an intended, albeit very minor, function of the power grid! It's amazing how things that provide only a tiny benefit to any individual but has an effect on such a massive scale that people actually sit down and spend time making it work.

rob74 2y ago

"Over a decade old" is technically true, but probably an understatement, to me it looks like something from the 1980s or maybe 90s? Apparently it's old enough to not have "planned obsolescence" designed in...

xnorswap 2y ago
You can see a "11/99 T1" sticker on the case, which might indicate a batch date of Nov 1999. The printing style on the sticker on the case feels later than 1980s too.
- rob74 2y ago
  Ok, then maybe it's a model designed in the 80s/early 90s that was still being built in 1999?
deleted 2y ago
[deleted]