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Neighbor's house alarm triggers when I put my car in reverse (reddit.com)
701 points by whalesalad 65 days ago | hide | past | web | favorite | 292 comments

This reminds me of a “bug” I found when working for a company that sells package lockers to apartment buildings. We used iPads for the user interface and had monitoring in place to alert us if an iPad went offline.

At only one location with two iPads one would go offline almost every day (but not every day) between 12pm and 1pm, for 10-20 minutes. Never the same time of day, and never the same length of time. It was always the same iPad, the other one on that network stayed online the entire time.

We replaced the iPad and the problem persisted. Finally I got fed up, put my phone on silent, ignored everything, and watched the Dropcam feed for the 2 hours near the usual time. Slowly I saw the sun light up the lockers, eventually shining on the iPad. Ten minutes later, after sitting in direct sunlight, it went offline. As the sun moved, the iPad went back in to shadow and came online on its own.

It was overheating and shutting itself off until it cooled down. The time changed because day lengths change, and the days it didn’t go offline were cloudy.

This reminds me of a story one of my college professors told about the days when he helped automate factories in the 80s. Every night, the control server hey installed would go offline around 1am then come back up a few minutes later. It was never the exact same time or duration. After a few days of diving through the code with no progress, one of his co-workers decided to stay up all night at the factory and just watch the server. Around 1am, the cleaning lady came in, unplugged the server and plugged in her vacuum.

There's a lot of permutations of this story including life support systems in hospitals I find them all apocryphal. The cleaning staff would notice right away if they just shut down a huge computer. Esp. in the 80s I doubt it even used the same outlet as a regular vacuum cleaner.

Some of them even had the mains wired directly into the case, so you couldn't unplug without an ax.

Correct, this is just an old urban legend


I too have heard this story, yet I had this exact problem at a k-8 school district, the staff would unplug the power to my t1 each night.

That co-worker later went on to invent the Roomba. /s

At one time I lived in an apartment building just outside of Seattle that had public retail space in the lobby. To allow residents and their visitors in after hours, a fancy touch screen was installed where you could enter an apartment number and it would phone the apartment where someone could then punch a number and unlock the door. Standard stuff.

Except that the touch screen could be activated by rain. In Seattle.

There was a small cowl over the apparatus to keep regular rain off, but if there was any wind at all, it was very easy for drops to be blown onto the screen and it would start phoning apartments in the middle of the night.

Amazingly, this was among the building's least troublesome faults.


Many years ago I had an optical mouse that would act erratically in the afternoons (just wouldn't register movement). It seemed to be ok if I squeezed it while I was using it so I figured it was a connection somewhere. Eventually I realised that it was the afternoon sun streaming in through the plastic seam and somehow stopping the sensor.

Reminds me of a wireless mouse I had that would intermittently become stuttery, but would usually fix itself whilst I tried to troubleshoot. I eventually realised that my laptop was between the mouse and its receiver, and any higher than normal utilisation of WiFi would interrupt the signal. Moving the receiver to the other side of the laptop completely resolved the issue.

I lived in an apartment in Fl and during the month of August and into September, every afternoon my cable would cut out for several hours. Happened every year for the three years I was there and only during that part of the year. Could never get Comcast to get a tech out there during the correct time frame, but they had a box mounted on one wall and that time of year it got direct sunlight and I suspect heat was to blame.

I worked for a cable ISP helpdesk once and during a particularly hot summer I vividly remember an on/off outage where we'd be getting regular updates from the field guys along the lines of: "We opened the doors and it works now." and "It failed again but we got a fan from the neighbors and that seems to help!"

I too had air temp heat related outages with Comcast. They finally dug up and replaced the equipment in the street.

In the 90s I was working a summer job as a forest fire fighter, and one morning the radio kept constantly beeping on one channel. Nobody could figure it out until a couple of hours later we got a call about a fire on a hillside on the other side of town. It turned out there was a radio repeater on the hill and the fire had burned through its power line, so it was beeping to tell us it was running on batteries.

I setup several emergency call beacons at a college (push a button, and 911 is immediately dialed, and a big blue light on the pole strobes, to help police find you). After 2 weeks of random alerts for a single beacon, we eventually determined it was the sun hitting the face of the device, expanding the button a bit. Rotated the face of the device 90 degrees, and never had an issue again.

Just curious, but what was the ultimate "fix" you landed on? Did you simply move the machine out of the path of the sun? Add a visor or something to the screen or window? Add something to cool the device down when it overheats? Switch to a different device entirely?

We added a $25 sun shade/hood type thing around it and the problem went away. Made the screen easier to see as well!

Reminds me of a story an old coworker told me. He was working as a repair tech back in the days when computers had tape drives. He was called out to a military base where they had just moved their computer one floor up, because the tape drive kept glitching. It would start up fine but then error out some seconds later, seemingly at random. After staring at this for quite some time he finally decided to stretch his legs and wander to the window. And what did he see, but a radar antenna rotating around. The glitches happened every time the antenna was pointed in his direction. On the lower floor it was out of the beam so there wasn't any problem.

I was working in a place that used to be a food store. Talked to the former owner, they had a big problem with all the freezers turning off during the nights and when they came to work all food was unfrozen and had to be thrown away. Turns out the timer to the sign outside was connected wrong and also turned off the freezers in the night. I do understand them, the electricity wiring in that building was not fun to work with... The place had been several different stores, all adding to the cables and connections over the years.

I posted this before in the "My wife has complained that OpenOffice will never print on Tuesdays" discussion [1], but it's worth repeating:

I heard a story about a terminal in a public terminal room that a user was able to consistently log in to if they were sitting down in a chair in front if the terminal, but never if they were standing up.

They thought it might be static electricity, or some mechanical problem, or "problem exists between keyboard and chair", but finally they noticed something else was amiss...

It turns out some joker had re-arranged the 1234567890 keys to be 0123456789, so when the user was standing up, they looked down at the keyboard and typed their password (which contained a digit, of course) by looking at the keys.

But when they were sitting down, they touch typed without looking at the keys, and got their password correct!

[1] https://news.ycombinator.com/item?id=11717010

Had something like that over a decade ago doing tech support for a government reporting agency.

Report: "If my secretary logs with our account, it works. If I do, the website logs in but then later shows me errors message when I try to submit a report".[0] Entirely repeatable. Screenshots sent showing it exactly. All of us scratching our heads. How could our web server know who was sitting in front of the keyboard?

Root cause: the username was a number with a leading zero. The login didn't care if you used zeros or not, but the internal logic did care. She logged in with them, he logged in without them (or was it the other way around?). Once logged in, the username was taken from a cookie or something that had been set at login time and fed into the internal logic, which barfed.

Lessons learned: either don't have forgiving logins, or have forgiving functionality when users use inconsistent logins.

[0]They were indeed sharing an account with the same username and password. It was 2005 and government website, so this made sense.

I would take a different lesson: use internally generated ids, not user generated usernames when communicating between services in your backend.

Well technically, the username the user had was generated by us when we signed them up. I honestly think this issue probably would have presented for 1/10 users whose IDs happened to have a leading 0-digit. Our software couldn't handle a situation we had setup for it.

But yes, I do agree with the general sentiment of "communicate via something internal, not something user-supplied".

I had a similar experience with a bug in a SaaS product that integrated with bank websites. They would send us the user ID and we would use that to determine whose account to log them into on redirect (and create a new account for the user if we hadn't seen the ID before).

At some point it became clear that they ignored leading zeroes during login on their end, but still included those leading zeroes when they sent it over to us, so we had a number of duplicate accounts. I purged the duplicate accounts (delete the newest, strip the leading 0s off the oldest) at the same time that they changed their code to send over the truncated number. All went perfectly, except apparently a few spouses were upset that they could no longer use their secondary account.

Makes me think of a story i ran into somewhere about a secretary that had sorted all the files on her office PC in different folders alphabetically.

This was back during the DOS days, and i suspect it was only discovered when she complained that it would no longer start in the morning.

It may well be that said joker had the best of intentions by sorting the keys in the numerical order...

I've read this seven times now and I just can't understand it. Can you elaborate?

I assume it means that they neatly filed COMMAND.COM in folder "C", and AUTOEXEC.BAT in "A", ... No filesystem permissions or file locking to prevent you from ruining your system in DOS.

But judicious use of ATTRIB +H +S did help ameliorate such things somewhat.

Check http://www.rinkworks.com/stupid/ for a treasure trove of similar helpdesk oddities.

I used to have a work computer that would get a bsod when someone other then myself logged in. I took a knife and scraped all the letters off the keyboard. It solved my problem in the sense that no one else tried logging on to my system.

Is it just me who'd love something like this to happen to me? Would be great fun tracking down the source of the problem (if it was my car; probably less so if I was in the house...)

There's a lot of options to try to isolate the problem, just thinking out loud here -

a) Back into the driveway returning from work. See if alarm goes off. Next morning, see if alarm goes off as you drive out.

b) Remove fuse for reverse assistant. (Stupid sensor thinking IR, ultrasound or RF sure-fire sign of break-in)

c) Remove fuse for reverse light. (Stupid motion detector confusing light for potential intruder)

d) Rev it up a little before shifting into reverse. (In case a resonance is the cause)

e) Roll out of the driveway in neutral. (Would be surprised if this triggered anything - if the car's movement was the cause, alarm wouldn't go off immediately upon shifting into reverse, only when it moved)

f) (...)

> Is it just me who'd love something like this to happen to me?

I love reading about interesting problems and creative ways to solve them. I used to wish for the same. But then I was given a super annoying one.

In my apartment I heard this beep about once every 90 seconds or so. I tried ignoring it for a while hoping it'd go away. And just so at the right frequency and infrequent enough Impossible to determine direction. But also just loud enough to be annoying after hours and hours. I spent several hours trying to pinpoint it. Including putting my head up agaisnt numerous neighbors doors to see if it was coming thru the walls.

I ended up downloading a dozen different audio apps for phone. And found only one that gave out an accurate enough histogram of dB volume level. Most weren't good enough. I needed to differentiate between 2 and most were sensitive enough of reading. I was able to triangulate the direction thru several patient iterations.

Turns out it was coming thru the wall.

Be careful what you wish for. Because you might end up with something arbitrarily dumb and annoying!

I had something along these lines happen to me years ago. It was sound-related, but didn't turn out to be electronic.

I was renting in a century-old house that had been converted into apartments. Every night, around midnight, this very high-pitched hum would start, and continue until almost dawn. None of the other residents ever heard it when they were around. While the exact timing varied, the time during which it happened overlapped with my sleep schedule (I was working a late tech support shift at the time) and it kept me awake. Earplugs didn't really seem to help.

There didn't seem to be any obvious source. I did exhaustive work to try and track it down - even got the permission of the owner and my fellow tenants to try shutting off the power at the breaker box in the middle of the night to see if that helped. (It didn't.)

It wasn't always constant, but it was around enough and preventing me from sleeping enough that I was going slowly insane. I had my ears checked for tinnitus - nope, I had and still have darn good hearing. I started reading about the Taos hum, looking into resonant frequencies, and finally stumbled across the answer.

The noise started a little while after everyone in the building went to bed. It stopped shortly after they got up in the morning. It was the sound of the century-old plumbing system at full pressure. If I just left a tap open a trickle, and the noise went away along with my sleep-deprivation.

I have what might be the exact opposite story.

20 years ago, in my first graduate job, we were issued pagers. One day my friend lost his - and it was on silent mode. We really didn't want to tell the company that it had disappeared.

Then we remembered that, at a certain time - I recall it being reasonably late at night - the device would emit a single, short, beep. I don't remember why, but even on silent mode, that beep would sound.

At five minutes to the hour - because this thing's clock wasn't synchronised, and we didn't know how accurate it was - we all positioned ourselves around the house. Silent as a mouse we waited, until - yes! - there it is, somewhere upstairs.

Now that we knew that it was actually in the house, it was just a matter of finding the thing. It was in his pants pocket - but they way they were folded in the wardrobe, the pocket wasn't where you'd expect it to be if you did a casual "pat the pockets" to see if it was in there.

Had a near identical issue 3 years back in my apartment! After tracking the source (ear on walls, floor and just figuring out where it was) i ended up discovering it was an alarm in the mechanical room below my apartment. There was a crack in the heat exchanger and it was a CO alarm, the disturbing part (lost sleep aside) was that my complaint about the sound is what alerted the building to the issue, and worse yet, their solution was to consider it a false alarm as they couldn’t see anything wrong and air the room into the hallway to stop the sensor (worked for around 30 mins until in unit alarms started going off too).

One day, years ago, I was working from home and I heard the intermittent "beep!" my uninterruptible power supplies make when they're unplugged and running on battery. I checked all of my UPS's, then turned off all of my equipment, but still every few seconds, "beeep! ... beeep!" It seemed to be coming from underneath my computer desk.

Eventually a spark of inspiration hit me, and I reached up and pulled the cord on the window blinds behind the computer desk. I found myself nose to beak (through glass) with a startled mockingbird. "Beep?" it said, and flew off.

I might be mildly evil, but I have deliberately caused a situation like this once in my life. I lived in an apartment with someone above and below me. At some point a woman moved in above me and my gf, paying way more than I did (par for the course in SF at the time). She was a super bitchy lawyer, and pretty shortly we started getting complaints that we were making too much noise at night. Keep in mind she was above us, so it wasn’t us walking around. She complained she could hear us talking and typing — but we were both really quiet people, and it’s not like I had a loud keyboard or anything. It was annoying and she wouldn’t stop complaining.

Eventually I decided to move out, for other reasons. My last act after everything was out of the place was to buy a cheap battery powered alarm clock, sat on a high shelf in a bedroom closet in a hard to see spot, programmed to go off at 2am every night for 5 minutes.

This is some brilliantly satisfying pure evil.

Off topic to the discussion, but you hit on something that struck a nerve with me so I'm going to go with it . . .

Oh good God, this happens to me every time one of my smoke alarm batteries starts to go. I have 6 smoke detectors and an older home where they're not all wired/battery back-up but rather all battery powered.

The "chirp at 90 second interval" thing is the worst design in the universe and it bites me every time. If I didn't know any better -- since there is no clock device and these things are not networked in any way -- I'd swear they are also programmed to only start chirping between the hours of 2:00 AM and 4:00 AM. I've lived here 10 years. I have never had one of these fail in the morning, middle of the day or afternoon; only in the middle of the night. Hunting down the one of the six devices that is failing with its way-too-infrequent chirp that's so high-pitched, only a dog could figure out where it's coming from, is made extra fun when you're in the fantastic mood that being awoken from a pleasant dream in the middle of the night and have the joy of hunting it down in your boxers in a cold house.

How much more complicated would it have been to also include a visual indicator. The things have an LED on them that continues to blink as the battery dies. Why not also have it either stop blinking (to conserve battery) or blink faster -- anything to make it easier to identify which of the infernal, identical, devices is in need of a 9-volt.

Thankfully, they're due for replacement this year. Now I have to research which of the models that are available handle this circumstance with a little more intelligence (that don't cost a hundred bucks a pop). This is such an easy-to-solve problem -- I don't want a "smart smoke detector", I want a $25 one that A) detects smoke and B) reports when it needs other attention in a way that is useful. Heck, I'd pay an extra $10 for the latter feature even knowing it would cost them no more than the "dumb chirp" method.

There was a very bad house fire a few miles from me about a year ago and the person who lived there died in their sleep while the fire raged. The rumor was that the home had a bunch of smoke detectors without batteries in it and it was spread through our neighborhood as a "cautionary tale". I'm willing to bet there's a story of being woken up in the middle of the night for a battery change chirp in there somewhere.

When the battery is weak, fire alarms have a tendency to chirp in the middle of the night because lowered temperature affects the battery negatively.

Your observation of the unhappy timing is probably related to the temperature. Cold batteries have lower voltage across their terminals, triggering the chirp.

(You can troll people into thinking you have magical powers, rub the batteries of a just-failing calculator/scale/wristwatch in your hands and you'll get another ten minutes of use out of them)

(Un)fortunately there are things that are written down in standards, like the LED blinking behavior, that the manufacturers can not change if they want to legally sell the devices.

You can get a smoke alarm with 10 year battery life to reduce the likelihood of this happening. When all are purchased in one batch, you can then pretty much replace them all at once -- if first battery goes, next ones are soon to follow.

I got some unconventional looking ones from Jalo Helsinki [1] for my house. They work well and look good. However, I know some people working at Jalo, so my opinion is biased. There are several other long battery-life smoke alarms on the market from different manufacturers to choose from.

[1] https://www.jalohelsinki.com/product-category/smoke-alarms-1...

You could also just buy the Lithium 9V batteries instead of Alkaline and put in your regular smoke detector - same result https://www.amazon.com/dp/B01684J7P0

If it runs on a standard 9V battery, then a very good option! Newer and smarter smoke detector chips are designed for 3V lithium-manganese dioxide batteries.

Can you seriously not add a "Change Battery" LED next to it?

In theory, you can. However, the standards also mandate that the "annoying" function has to work at least few months after the battery is low. Adding an extra LED there will consume too much power.

Vaguely related - I once met a parrot that had learned to imitate that exact chirp. Maddening.

I know a caique that learned how to imitate a ringing telephone. They had to replace all the phones in the house with a different model, because they were constantly looking at dark caller ID panels that didn't ever say "your parrot".

Back when Facebook used a "pop" sound when you get a message, I was able to imitate it well enough to make my friends in the same room check their computer for messages!

In the late 90's early 00's, we had a pet cockatiel that could perfectly mimic the sound of dial-up modem dialing. He would also do the tunes to TV theme songs and a few regular TV ads.

The whole house hard wired smoke alarms are just SO FUN when they start to fail. The one that is failing immediately sets all of them off, but only once at 3AM every night for two weeks. So you get woken up by a brief ear piercing alarm from around the whole house and have no idea which one it is.

I had a battery powered one that randomly triggered in the small hours. I'm very sensitive to loud high-pitched sounds, so I woke up with a fright that must have aged me 20 years. Tore that thing off the ceiling, nearly pulling a chunk out with it. Landlord was very unhappy with me doing that, but it was right over my bed.

If I'd had a baseball bat or wooden sword, I'd have smashed that thing free like a piñata!

Elsewhere in the thead I was moaning about this design, as multiple times it’s been in flat in our neighbours house and I’ve been checking ours. Can’t they just die quietly? If you aren’t checking them periodically anyway, you don’t know they they work.

They shouldn't, unless you want to risk dying with them :).

That said, everyone should check their alarms at least once. You should be able to find appropriate "testers" to purchase with alarms. I use CO alarms at the place I live in (gas-heated water), and each of them I tested with what I affectionately call "carbon monoxide in a spray can".

My buddy's dad was an EE and built tiny devices made to create this exact situation. Easily hidable, they emitted a loud beep sound at a varying interval (~40-120 seconds). He called them Annoyers and would leave them behind pictures frames, in plants, etc. after parties.

There's a version of these called the Annoyatron that you buy online. Know how I know this? Because one of them was left behind a cabinet in a rental house we moved into and we couldn't find what was making that damn noise for three months!

This seems like a particularly evil variation of that idea:


I think this one is even more evil, because it forces you search in the dark.

This in fact is a very popular around the world electronic kit for beginner hobbyists, because it's trivial to build and has only few components. I remember it from electronics magazines in Poland.

We had a fire alarm going off due to low battery once. We searched the house for 3 hours trying to find it. Gave up, slept through the beeping.

Next day, enraged, we tried again. Eventually we found it in the bathroom trash can.

Just did this yesterday, and eventually found it was the neighbours one that was flat. It’s the 3rd time I’ve knocked on a neighbours door (different people each time) to ask them to take a battery out an alarm. I’d consider it a feature if they combusted after alarming for a day.

I am Deaf. In the night you would need to break into my flat, too, because the flash indicating the door bell is in the living room, not the bed room. Nobody and nothing disturbs my sacred nightly sleep.

It's amazing that people can just tolerate or not be aware of things like this.

My nemesis was one of those round stick-on LCD clocks that used to be popular.

The designer apparently thought that emitting a single beep every five minutes or so would be an awesome low battery indicator.

I didn't know what kind of thing was making the beep, naturally, which was unhelpful.

It took about a month of me slowly going mad before I finally found the thing at the back of a desk drawer.

My house has 6 fire alarms, when they beep there is NO way to tell which one it is making the noise 2/2 the combination of short beep and irregular beeping interval.

My solution is to just change all the batteries at once so i dont have to guess (and if you guess wrong you then you wont sleep tomorrow because of the beeping)

I wish there was some visual indicator to tell which one was faulty.

My smoke detectors made a boast on the packaging they featured a fool-proof low battery indication, without going into any details.

I bought half a dozen of them to install in our new house years ago, thinking the nightly find-the-beeping-^+=¥€ games were finally a thing of the past.

When one started beeping, I did the rounds, figuring I'd be back in bed in minutes. Well, I wasn't. Turned out the fool-proof indication was to have the normally green LED flash red instead.

Did I mention that I am colour blind?

Unfortunately as some who isn't colour blind and doesn't have any close friends who are, it's easy to forget about these concerns. I think attention to accessibility issues like this is one of the things that separates great designers from good ones.

Oh, it isn't all bad - now I get to kick my wife out of bed to find the offender, instead.

The smoke detectors in my house are supposed to do that, but many times I've found one chirping and the light is nice and green.

I believe they all beep because they want you to replace all the batteries.

I had this happen a few months ago except it wasn't a low battery alarm. It kept yelling "FIRE FIRE" but then turning off. Of course FirstAlert apparently doesn't indicate which alarm is causing it. They say the initiating one flashes a different pattern but I didn't find one. Ended up, after getting no sleep at all, replacing all 9 of them with nests. At least then if one fails I'll know which one.

This who thread had me feeling twitchy. How did any of these product designs make it to market?

They weren't (probably still aren't) regulated enough.

Manufacturers can get away with it because even if they screw up, an angry customer doesn't really affect their sales in any meaningful way.

Aren't Nest Protect alarms also linked? This harrowing video leads me to believe they are. It's a couple years old at this point though. (Turn your sound down, video is a poor soul trying to deactivate them.)


That reminded me of an iOS quirk that thankfully has since been resolved.

A few years ago I used "Find my iPhone" to chase down my phone in the house, buried under some pile or another. Unfortunately I had earlier been using AirPlay to play music through remote speakers, so of course the emergency tone played through the speakers, not the device.

Which app did you use

So what was it?

The others were correct. It was the neighbors low battery smoke alarm.

I had high suspicion that it was that. But not hearing it thru neighbors door. And with how loud it was and the fact I could hear it thru my front door and not theirs. Made the hunt for it so much harder.

Not him but I'd bet 5 bucks it was a smoke alarm with depleted batteries.

I'll add a related real life debugging tip I've seen play out at least twice in the real world:

If you can't get an alarm to shut-off or stop beeping, no matter what you try, then give serious thought to the possibility that there's a second alarm nearby which is the source of the noise.

About a year after I moved into my previous house, we heard that familiar chirping sound.

After 3 goddamn hours of searching, and having run to the store to buy 9-volts and replaced every goddamn battery in the house, we found a carbon monoxide alarm thrown INSIDE the return air duct of the HVAC unit...

Which is a reasonable place for one, as it will trigger from excess CO anywhere in the house when the HVAC is running. The problem is only obvious when you're not the original tenant who installed the thing.

Wonder if a full battery with a resistor in series would prolong the agony.

Or a NiCd in place of an Alkaline battery.

Here is $5. You are right.

And what was the app?

I forget now. Was over a year ago now. It was just one that allowed me to zoom in on a specific point in the past 60 seconds of sound in real time to see an exact dB reading for a very specific and tiny spike.

To my ears it always sounded the same volume. And to some apps. It wasn't considered loud enough to be read in a meaningful way.

Time for my story.

I was a noobie computer programmer in my first job. After being there for a few months my mouse started to have issues. It stuttered and refused to move correctly.

So I'd take the little grey ball out and clean it and it'd be OK again. But the next day it'd do it again.

So I ended up with the cleanest fucking mouse on planet earth. Yet every so often it'd stop working... on parts of the screen. Other parts it'd work. I ended up using the keyboard a lot.

The mouse would work fine all day some days. Some days it would work fine until about 2PM then it may or may not work.

Eventually I figured out that when the sun shone through the window it created a beam across my mouse mat. When the mouse was moved into the beam it would stop working. So I took it to bits and discovered that the ball would roll a little disc, that disc had little holes in it, there was also an LED and a photodetector. So the mouse was counting the blips in light to determine the movement in the mouse. I guess the cheap plastic was allowing the bright sunlight to bleed through the case causing the photodetctor to go bonkers.

A secondary thing about that cheap as shit PC was you could hear the video card render the screen. It'd buzz when the screen was mostly blue, when it was white it would be silent.

Ha, my mouse scroll partially stopped - turns out it's a rotary encoder like you describe, some of the gaps get blocked with dust and the mouse stops scrolling, a bit, still scrolls but seems intermittent (like a software issue), was a couple of days before I opened it up as I was looking for a fault in logs and such.

Of course opening a mouse up and not breaking it is quite hard, they're made to break and be replaced. Current bugbear is Logitech keyboard stand pieces that appear only to be there to break and thus require keyboard replacement - again it seems a design with a penny's more of plastic would be almost invincible.

I recall a story on reddit's talesfromtechsupport a printer would stop working at a certain time of day. I think it was near a skylight or something weird. I have no idea what it was about but your story jogged my memory but not enough to remember it all.

Yes that's it. Excellent search fu you have.

Entered the next line into Google and it was the first result:

site:reddit.com/r/talesfromtechsupport printer stopped working skylight

lmao I should trust my brain and type it verbatim into Google

Even worse than that I had already saved the post when I read it the first time.


Ubuntu doesn't print to Brother printers on Tuesdays.

Wait, you had a buzzin when the video card is active as well? Was yours dependent on the refresh rate on the video card? (I haven't found any other mention of a similar problem elsewhere, and mine has been doing that for a few years now.)

I can hear a small buzz when something is rendering as well. Turns out that in my case it was coming from the VGA cable making interferences in my loudspeakers cable.

Moved the VGA away from the RCA, no buzz now.

'Coil whine' is the usual cause of that sound.

Here's my odd story. Years ago, my wife and I were sleeping over at my parents house and we were awoken by garbled conversation from the clock radio. I sleepily checked it out and saw that the radio was turned off. Thinking that the on/off switch was broken, I just unplugged it. The garbled conversation continued. At this point I wondered if my parents house was built on top of an ancient burial ground...

Talking to my father in the morning, he indicated that his neighbor had taken up Ham radio and he was having to put filters on various devices to reduce interference. To this day, I wonder if his spotty wifi in the house is related to his neighbor turning his system...

Something like this happened when I was a kid and it scared the heck out of me. Suddenly there was this loud garbled voice booming from the stereo speakers. I thought it was the devil or something. Turned out to be the radio enthusiast who lived next door. There was a big antenna in their backyard, so they were probably broadcasting with some power. Plus my dad had the whole Hi-Fi rigged up with lamp cords.

I knew someone who lived two blocks from a radio station, and they would get interference everywhere, there would be staticky top 40 music coming from the phones, from clock radios, from the stereo. It would come and go. They would complain, the radio station would fix something, but in a few months it would be back.

> Plus my dad had the whole Hi-Fi rigged up with lamp cords.

He was probably onto something.


It seems like a bit of a stretch, but in theory - depending on the details of the radio, and the power being emitted by the neighbor's station - you might be able to get some audio from a "powered off" radio. Maybe it's doing something like what happens when a crystal radio[1] absorbs enough power inductively to generate its audio.

[1]: https://en.wikipedia.org/wiki/Crystal_radio

I've heard stories of unplugged loudspeakers turning into AM radios with enough power pumped into the air, so there's that too.

AM radio has all kinds of "fun" properties.


Listening to the tranmission using the arc the tower generates to ground!

Nice! But I like the Russian (or Ukrainian?) approach better:


Holy %!#@! That is one of the most interesting things I've ever seen.

Can confirm.

Of what little I read of the reddit thread, there must not be many gear heads in there that debug software, too. I say that only because there is a lot of “it’s probably...” but no “try this, which will eliminate $FOO. Next, $BAR, which eliminates $FOOBAR.”

For your list, and I’d do a) and not bother with b) and c) as a) eliminates them well enough (point the emitters away from the alarm sensors). For d), I’d put a light cloth in the tailpipe, enough that it will change the exhaust note across RPM range, but the car will still run. Your suggestion leaves the slight possibility of a false positive if we accidentally hit the resonant rpm range. For experimentation only, don’t drive to work a banana in your tailpipe.

One last one: throw it in reverse near the house, but not in your driveway. Could be some weird parabolic blah blah acoustic thing focus thumpy exhaust waves at the house sensors.

I suppose there’s the possibility that a 2.4Ghz radio transmitter of some sort could be responsible, but this way out there and would be way down in my list. SDR and a dongle would be handy here.

Seems like there are two possibilities: engine noise is causing windows to vibrate making a sensor go off or the reverse distance sensor that uses microwave radar (X band) is causing the base unit to think a sensor is going off. It is a WRX (lots of rumbling engine noise) so I would imagine that the first scenario is more likely. A home alarm system is most likely going to be 433MHz (or even the wifi/bluetooth bands) but not X band.

0) Ask neighbor if they have any idea what's going on. Modern alarms usually at least indicate which sensor triggered.

> What does your neighbor think of this lmao

> > I don't have time to stay around because I tend to lag for work and have to leave as soon as I do get to my car.

How ... convenient.

I had to debug my home this summer and I think it makes a good story. I have been renting this appartment on the ground floor for one year, and for environmental and economical reasons, I decided to try to reduce my electricity bill, which was quite large for the size of the appartment. An obvious culprit was the Canadian winter in a poorly isolated place, but I was also wondering about why in summer I had around 22-23 kWH of electricity consumption every day. I have no A/C, so I figured it was either my electronics or the appliances or a combination of both.

I bought an electricity usage monitor plug and started to measure every electricity consuming stuff, but couldn't account for more than 3 or 4 daily kWH. Then I went in vacation for one week, turning off almost everything in the house, and the electricity consumption, that I can check every day, had barely moved. Something was consuming at least 20kWH every day in my home and I didn't know what it was.

At the same time in prevision of the winter, I bought a thermal IR camera to spot isolation problems. I started to play around with it, and discovered a fairly large hot spot in the bathroom, on the bottom of the bathtub. Touching it with the hand, it sure felt warmer than you would expect from a baththub. Maybe it was some hot water? But the water heater was on gas and my gas bill was fairly normal. The hotspot would also not go away after hours. Then I remember a visiting friend remarking weeks ago that my bathroom was warmer than the rest of the appartment.

To test my suspicions, I tried to play with the electricity meter of the appartment. After some experiments, I found out a switch that would turn off the mysterious heat source. The baththub started to cool down and the power usage displayed went down to 0. My theory was validated! Something under my bathroom was drawing around 800W constantly every hour of the day and every day of the week and that was making my appartment so hot in summer and my bill so large.

At this point, the only thing I could do was contacting my landlord and detailing my findings. It turned out he had installed a dehumidifer in the basement the year before to dry out the air and fight a moisture problem, but he had configured it to a very low setting, like 30% humidity and that was making it work constantly. The dehumidifer was installed just below my bathtub and its operation was heating it at the same time. Since it was an old home he had bought out a few years before, he didn't know where the basement was drawing its electricity from. Well now he does.

He reimbursed me the electricity and changed the settings of the machine and then my electricity consumption went to almost nothing... until november came and the cold of the last weeks of fall started to hit Montreal, but that's another story.

So what's the other story??

Actually imo it makes most sense to call the alarm company and have them troubleshoot it while you're there with the car.

That way they can see debug output of what happens when he hits reverse.

f) Try putting car in reverse with the engine off

[as someone else already said]

I’d be super surprised if that turned up anything. For one thing, okay, we did that and the alarm didn’t go off. What did we eliminate? Alternatively, if the alarm did go off, this ex-mechanic would be at a loss as to how a car with no powered systems could do that. At that point my suggestion is to call a priest.

Well, putting it in reverse with the engine off but with electronics on would potentially let us rule out anything related to sound from the engine, and would mean it's more likely something related to electromagnetic waves or something else coming from the onboard electronics.

Theres a small but non zero chance it's something to do with ultrasonic backup sensors - so I'd try this with everything powered up but without the engine running, mostly because it's a super easy test rather than any real expectation that it'd be the problem.

Ah, engine off, but powered electronics, got it. Yeah, small chance of finding a bug but offset by being an inexpensive test to run.

> For one thing, okay, we did that and the alarm didn’t go off. What did we eliminate?

Weird EM interference from electronics, ultrasonic backup sensors, Magic Stuff Related To Reverse #1.

> Alternatively, if the alarm did go off, this ex-mechanic would be at a loss as to how a car with no powered systems could do that.

Maybe it was caused by Magic Stuff Related To Reverse #2, or maybe it turns out the system is actually powered when you thought it isn't.

Looking over your other comments in this thread, I feel like you're approaching the topic from a position of someone who's an expert in cars and electronics, and thus has almost everything important in their memory already. But in cases when one isn't an expert with a thing one's debugging, I'd err on the side of doing the tests that seem ridiculous, at least if they're cheap to do. Discovering that it's probably Magic Stuff Related To Reverse #1 is a fair result, and should then be followed by reading up on what else gets activated/actuated when one's car gets switched to reverse.

Happened to me once and drove me nuts. And let me to fight with my housemates. Not worth it.

My fire alarm goes off once every few months at 3 AM.

From what I heard this is not uncommon.

Try cleaning it with a vacuum cleaner. Was listed in the manual for mine and it hasn't false alarmed in years since we did it.

I don't want to be your neighbor :P

Time to revisit the 500 miles email... http://web.mit.edu/jemorris/humor/500-miles

Funny how he went about troubleshooting. I guess it was a long time ago and they didn't enable logs to save disk space.

Because me being a sysadmin for the past 14 years would go directly to the logs and see my client timing out.

Now, _that_ was an extremely amusing read!

When we were kids (dating myself here), my friend had a TV with a remote control back when almost nobody had a TV with a remote. You would push the channel-change button on it and the channel knob (!!!) on the TV would mechanically turn and the channel would change. Well, apparently, the remote used an almost-audible high frequency to signal a channel change and when his dog ran through the living room, the dog's tags would jingle and change the channel on the TV.

We had one of these as well -- a fairly standard routine of TV after dinner before going to bed quickly taught the dog that the ultrasonic sound made by the "Off" command to the TV meant "everybody go upstairs and go to bed".

You could actually just press that "off" button at any time, and the dog would look around and do that funny "Dog shrug" thing they do, and go upstairs and lie down, even if it was the middle of the day. We had, essentially, a remote controlled dog.

My dog was similar, but the sound he triggered on was the CRT turning off. You could sit perfectly still and press the off button the remote (so as not to give any body language signs) and he'd wake up, and wander off to the bedroom for the night.

When I was young and my hearing was better, I think I had a slightly-better-than-normal upper end to my hearing. Often, I would hear CRTs whining that no one else did.

I vividly remember when I realized it. One day in class we were watching a tape and the TV was whining the entire time. After the tape was over, the teacher started talking about what we'd seen, but didn't turn the TV off. I asked him to, because the sound was so annoying. A bunch of kids started saying they didn't hear anything, which made me think I was crazy until one other kid stuck up for me and said she heard it too.

Same here! I remember waiting for a lift where my friends mother worked, a car rental place. I told her I could hear a TV on somewhere, and she insisted there was no TV nearby. I persisted, it was driving me nuts. Finally, she remembered the cupboard above our heads had a TV in it. She opened the cupboard, and low and behold, it was on, on mute. I felt like I belonged in the X-Men.

Lo and behold, oops

Downvoted for correcting my own mistake??

I can also hear a CRT on anywhere in a house/office. One of the best things about the transition to flat screens is that the annoying high-pitched whine that accompanied CRTs has gone away. Now I only hear mode scanning/input skipping flat screens. At the same time, i do feel like I've lost a bit of a super power.

You're hearing the flyback transformer vibrate. I could hear CRT TVs like that, but I haven't been around one in years.

In television sets, this high frequency is about 15 kilohertz (15.625 kHz for PAL, 15.734 kHz for NTSC), and vibrations from the transformer core caused by magnetostriction can often be heard as a high-pitched whine. [0]

[0] https://en.wikipedia.org/wiki/Flyback_transformer

this noise is commonly referred to as coil whine and is made by any high voltage electrical component. The sound comes from the electron gun which has very high voltage passing through it. If you cant hear it you have hearing damage because most crts make the noise just on the edge of human hearing https://en.wikipedia.org/wiki/Electromagnetically_excited_ac...

Me too! I remember being able to predict that we were going to watch a movie in class because I could hear the CRT whine from the hallways before I even walked into the room.

I could hear that too! Actually nowadays I hear it all the time because I have a tinnitus that is pretty close to that frequency. :-/

Oh man... I had totally forgotten that sound until you mentioned it.

Haha "remote controlled dog" was funny. You've recreated Pavlov's experiment albeit updated it for our tech century :D

Fantastic story, thanks!! ;-)

When working on plain old telephone system (POTS) multiplexers, I came up with the following story which a service engineer insisted was true:

An elderly lady with several pets called the operator to say that her telephone failed to ring when her friends called; and that when it did ring, her dog usually barked first. The engineer went to investigate.

He climbed a telephone pole next to the house, connected his test set, and rang the line to subscriber's house. The phone didn't ring, but the dog barked loudly. He tried again, now the phone rang.

Climbing down from the pole, the engineer found:

- This was in a country where the ringing was done from one of the wires against ground (not across the pair) (I think it was England).

- A dog was tied to the telephone system's ground post via an iron chain and collar.

- The ground post was in dry, poorly conducting ground.

- The dog was receiving >50 V of ringing voltage when the phone rang.

- With this torturous treatment, the dog would start barking and urinating on the ground.

- The wet ground now completed the circuit and the phone would ring.

OK, this story has a definite "urban legend" ring to it. Mythbusters wouldn't have tested it with a real dog, I guess.

I (accidentally!) had the misfortune of torturing the cat in the apartment directly above mine, many moons ago.

I had built myself a simple modem for packet radio (ham radio; very slow modem for use on shortwave bands), and wanted to test it. However, I was at home, and at the time I used either the HF station I had installed at my office in the university or the one at the radio club down the hill.

Heck, I'd only try some local comms, anyway. I got an old transmitter out of a cabinet and strung up a dipole antenna under the ceiling in the living room. I tied one end to the curtain rack either end of the room, called the radio club, agreed on a frequency, and off I went.

When I keyed the transmitter, I could hear a commotion starting upstairs. It died down, and I didn't think more of it. After a while, new commotion.

Next day, I met the occupant of the apartment above at the mailboxes; she said her cat had acted up last night - running around the living room like it had the devil on its back.

Turned out it had a metal collar, and loved to snooze on the floor right under the window, as the radiator on the wall below the window made it real warm and cozy there.

When I keyed the transmitter, I basically had a very high RF voltage at the end of the antenna - and the cat, whose collar was a mere few centimeters away, got enough of a current induced in it for the cat to go ballistic. Poor thing.

This story has been doing the rounds since at least the 1980s. I remember hearing it from a BT engineer who was visiting our school back in the day. No idea if it's true or not, but it had certainly reached UK shores as of ~30 years ago.

Very likely so, it's one of those legends that circulate round and round. I heard it when making a PSTN mux for (among others) UK market in about 1995.

> OK, this story has a definite "urban legend" ring to it. Mythbusters wouldn't have tested it with a real dog, I guess.

It would be easy enough to test without involving a dog. They've done plenty of electric-shock myths with ballistic gel dummies.

Fair enough, but they'd have to build a voltage-triggered barking device in the gelatin dummy to make it sufficiently life-like.

I remember when I was a child than my next door neighbour had a remote control on their TV, which was connected to the actual set via a 5m thin cable.

I thought it was pretty cool that she could sit on her chair and change the channel & volume without getting up.

I suspect that if a dog had been involved that cable would have quickly become a tangled mess! (I'm not sure how common "wired remotes" were, that was certainly the only one I ever saw, in the early eighties.)

I remember seeing a really old pneumatic remote for a TV a long time ago.

It was basically a rubber squeeze pump (just like on a blood pressure machine) and a rubber tube connected to the tv. When you squeezed the pump, the pressure in the tube would click the dial forward one notch.

Reminds me of the time my siblings and I tried to build a manual remote control with K'Nex.

We had a wired remote for our VHS tape player in the 80's [0] as well as a cable TV channel changer [1].

[0] Was this exact one: https://i.ebayimg.com/images/g/kyIAAOSwz71ZPcLZ/s-l300.jpg

[1] Looked something like this, IIRC: http://1.bp.blogspot.com/-O2PtM-x0fDc/UyFjySzfuCI/AAAAAAAAJ9...

I only ever saw one wired remote to the best of my recollection. It was on an old Sony Beta tape deck my parents owned. (This is from the 80s as well.)

If the remote used an almost-audible sound frequency, the dog probably heard it, too... which would basically mean the remote had a failsafe...

In about 1977, we had a TV with a remote control. Very often, sneezing would cause the channel to change. I think jingling a keychain would cause it to happen, too.

> the dog's tags would jingle

What does this mean?

I presume, the dog was wearing a collar with some metal tags that bounced off of one another, making sounds of similar frequency to the ultrasonic remote.

Metallic dog tags make a jingling sound when the dog moves.

The metal pieces would hit each other creating a jingling sound.

Merry xmas!

My guess is that the backup camera has an IR light to assist with nightvision. Some security cameras support triggering alerts if they get too much IR light because blasting them with an IR floodlight is a common way to blind a security camera.

Maybe its a backup sensor? The sensors on newer cars make radar detectors go nuts. It’s hard to say without knowing anything about the neighbors security system.

Shortly after a big upgrade to the application I worked on, we started to get bug reports on our forum about a pretty ugly bug where a modal window would get “stuck” after clicking OK. The window would no longer respond to users but the application would act as if it were still up, and the only way out was to kill the process and lose all the unsaved work.

Understandably, the complaints got louder and angrier as no one on our engineering or prerelease teams were able to reproduce it, but easily half the bug reports were all about this issue and identical. After 2 weeks of trying every configuration of video card, OS, and any other alchemical recipe we could think of, my partner on the test team stumbled upon the license crack online while searching for anyone else having this problem but not having reported it to us directly.

As a brief respite from this ongoing madness, he decided to install the crack on a clean machine and aee how it worked so we could report it. Lo and behold, the problem reproduced on the first try. This whole time, indignant, angry users who were actively threatening our team and vowing to never use another product from our company had been bested by a poorly written crack.

Before exposing the secret, I asked dozens of the most vocal and vicious reporters to please email me a particular log file, and give me contact information where we might get in touch with them as we were close to cracking the case. (Pun intended, and this was before we had very clear rules around personally identifiable information, but even with the policy at the time, these weren’t our customers so I felt less anguish about it.). I received all of it and more, invited them to share their experiences on the forum threads, and then tactfully but clearly explained exactly why they’d seen this problem. I offered to work one on one with anyone who felt my accusation was in error, but not one single affected user replied or followed up after that message.

I was a junior developer on a heavily used utility that was frequently pirated. The company tried a few strategies to deal with this but one of the best was incredibly sneaky.

This was before validating license keys over the internet was really possible so a lot of people just used our application with a key from a public cracking site. Of course, we also knew about this list of cracked keys and our application would pretend to accept them. But if you actually tried to use the application, it would appear to be doing something for several minutes but fail with a mysterious error inviting the user to submit a log file to support.

Of course, the log file was secretly marked to indicate that it had come from a pirated copy and the customer would get a polite call from the sales team.

It worked out pretty well, a lot of customers didn't know they were using pirated software (or so they claimed; somewhat plausible given the nature of the utility) and were happy to pay and the sales team got a lot of solid leads. Evil vanquished, good prevailed, and I got paid.

This is great!

We had a problem with piracy for awhile. We spent nearly a million dollars on some of the best licensing software out there and over 2 years of tweaking it to try and eliminate all attack vectors and we still had piracy. We learned even the best anti-piracy methods will be broken eventually. In the end, the proper solution was pretty simple... we just rewrote our application as a web app and now only people who pay can login.

I mean come on people, if you're using professional software and expect to be paid for your work, pay the other professionals for their work too.

Excellent tale. It is sadly unsurprising that users get so upset about software they don't pay for.

If I may be permitted a brief comment, I recall several years ago a situation where we received complaints that our rather computationally-intensive software was running on some people's laptops without them having installed it, rapidly draining their batteries and heating the machines up, and what did we think we were playing at hijacking their systems?

It turned out that the culprit was a modified version of our software for a distributed computing project that would apply the credit generated to one particular account, presumably belonging to the user who had distributed the cracked version. IIRC (though I may be mistaken) they were distributing it bundled with some other cracked Windows software.

Got a kick out of this gem from the reddit comments:

> My S2000 car alarm would be set off whenever I microwaved blueberries. Some experimentation revealed it was anything with excess water. Buying a new microwave solved the issue but I don't like thinking about how poorly shielded the old microwave was. I tried moving the for further from the kitchen or keeping the keys far away to no avail.

I think a lot of microwave ovens are poorly shielded. I’ve seen more than one that will kill WiFi a room away, including the one in our house.

As for the S2000, I guess water coincidentally changes the frequency of the leaked radio waves to match the car alarm?

Indeed. Several years ago, I was working on a 2.4GHz device, and we noticed that occasionally, the microwave in the office kitchen would disrupt things. A quick check with a 2.4GHz band spectrum analyser showed what was going on:


The company being as cheap as it was, I simply began using the microwave as a deliberate noise source for testing the device's operation under adverse conditions, placing a few mugs of water in the microwave for a few minutes, and deliberately setting my channel to collide with the microwave.

Why would someone microwave blueberries?

They were frozen... Out of season it is the only way to buy blueberries.

Making sauce or heating up a muffin, I guess?

Or frozen blueberries, but why would anyone buy frozen blueberries.

> Or frozen blueberries, but why would anyone buy frozen blueberries.

Because they are available and inexpensive year-round, and they defrost well and are good in many applications. Outside of the peak of local season, its the best way to buy blueberries.

Maybe they had the kind that grows in the wood and not in the shop? ;) When you pick berries it is normal to store them frozen to have through the winter

why would anyone buy frozen blueberries

Because 'fresh' blueberries out of seasons cost 3 times as much and taste like nothing much.

> but why would anyone buy frozen blueberries.


Assuming they mean the frozen, bagged ones.

To make them explode.

When I lived with my brother and played a lot of WoW I would get disconnected almost every night at around the same time, and usually in a Raid which was quite annoying.

Eventually I tracked it down to microwave usage. Whenever the microwave was in use, I lost WiFi.

Did your brother ever use the microwave offensively against you? https://xkcd.com/654/

Reminds me of "story of a car that wouldn’t start every time its owner bought vanilla ice cream". http://www.kepner-tregoe.com/blog/help-my-car-is-allergic-to...

That story is so incredibly far-fetched, and further comprised by the not-so-subtle product plugs liberally sprinkled at every turn.

It sounds like it was written or told by an engineering person and then mangled into this BusinessExecutive™-speak by some marketing person.

And the story doesn't have that big a payoff to justify that either.

All the plugging did was make me slightly annoyed and averse towards the brand and that bloody catchphrase.

The story has apparently been recounted and rewritten many times since at least the "June 1978 issue of Traffic Safety magazine".


That makes the biz-speak story posted on the KT website all the more distasteful.

Please, somebody, create a website that centralizes all these weird bugs! Could be a very good resource to "debug things", try and approach problems with different approaches.

It's a bit more serious, but good old RISKS DIGEST is worth a read for this kind of thing. https://catless.ncl.ac.uk/Risks/

When I worked at an NOC for a fairly large ISP they told me a story of an intermittent outage that occurred randomly on weekends. Something was injecting insane amounts of RF interference on the lines. They tracked it down to the node, then the neighborhood. And then finally they found the culprit. What was knocking the network out of whack? It was some guys edge trimmer. The motor in it was injecting crazy signals somehow. The ISP bought him a new trimmer and promptly took pictures of this one and destroyed it. Never had an issue with RF again.

> The motor in it was injecting crazy signals somehow.

It was too cheaply made to have an interference suppression capacitor across the supply leads, is how. Bet he got it from Harbor Freight...

On a related note it’s interesting how electric shavers (which could easily suffer from the same issue) are allowed on aircraft, but mobile devices need to be in flight mode. Are the frequencies of RF noise from an electric motor in a different range, so they don’t cause issues with aircraft?

The problem with electric motors is back EMF, not so much RF - motors don't spin that fast. (Switch-mode power supplies do switch that fast - into the hundreds of kilohertz - which is why cheaply made and thus poorly suppressed ones do tend to produce radio noise that you can hear, in harmonics at least, in the lower AM band. It'd be rare to find a tool motor that spins much over 30K RPM, and even that's on the high end.) So the noise is too low frequency to qualify as RF, but you're still dumping inductive voltage spikes into the supply, which can destabilize other equipment on the same circuit or one nearby - in this case, while the neighborhood concentrator might not have been (probably wasn't) on the very same circuit as the trimmer, it probably was on the same transformer, or else the circuits ran parallel in a conduit somewhere and the noise was getting capacitively coupled into the concentrator's supply.

This wouldn't be a problem with a battery-powered trimmer because it isn't connected to the aircraft's hotel supply - or if it is, it's through a wall wart, which will contain a transformer and at least some suppression circuitry, which will dissipate any EMF that makes it out of the tool. And in general, the way you suppress this kind of inductive noise is with capacitors and chokes, which any reputable manufacturer of a line-powered motorized tool will include in the design. But there are a lot of disreputable manufacturers out there, too.

It's not the aircraft they're worried about, it's the cellular network. The phones-in-airplane-mode rule is an FCC thing, not FAA.

Another thing they don't want on take off or landing is a bunch of dense wedge-like objects flying around in case of a fuck up.

Reminds me of someone having trouble getting their Tesla to charge after the power company installed "smartmeters". The reason was that the model they had picked was one that used the power lines to transmit the readings, and the added noise tripped the Tesla's sensitive charging circuit.

I guess this could be fun depending on how much you liked your neighbors.

I had something like this happen once that was interesting. We had recently got a Simple Human automatic soap dispenser and had it sitting in the kitchen by the sink. I was bored and started playing with a small RC helicopter and kept hearing a weird noise but didn't know where it was coming from.

For whatever reason, every time I would throttle up on the controller it would trigger the the dispenser to dispense soap as if someone had stuck their hand under the sensor. I ended up finding a large puddle of soap in the sink and then it clicked as to what the noise was.

Was it one of those cheap RC helicopters that uses IR for control and the IR blaster on the remote was triggering some kind of IR sensor on the soap dispenser that is normally trigger by a nearby hand?

Yep, just a cheap RC helicopter from Amazon with IR controller.

The comment from im_from_detroit [1] seems on-point, possibly ultrasonic sound from a backup sensor on the car being received by an ultrasonic detector in the house.

[1] https://www.reddit.com/r/cars/comments/7k12fs/neighbors_hous...

Op mentions later there are no sensors. So either a light/shadow thing or a sound/vibration thing.

There are no explicit "parking" sensors (it's not going to beep if you're about to back into something) but all but the base model have blind spot and reverse cross-traffic sensors. I can't find any explicit mention of the trim from OP. It's quite possible he's incorrect in saying he has no sensors.

I have a 2016 WRX with what should be the same exhaust. When you start the car, it starts with a high 2000-2200RPM idle and drops from there. If it needs to warm up, it will sit around ~1800rpm which is exactly where the stock exhaust makes the loudest drone.

So simply starting the car and letting it idle should result in it hitting all the revs that trying to reverse would (unless OP is awful at driving stick and way overrevving it here).

I find it way more likely there's a sensor interference issue than it's an exhaust issue based on the other information. My second guess would be some IR from the halogen running lights / fog lights / other lights in the car interfering with a motion sensor.

Engines sound deeper when you put them in gear, if he’s driving a muscle car or something, though I’d expect coming home in the evening would do it too in that case.

It's a WRX.

Is there a way to vote this as the funniest HN submission of the year? I started laughing and when I thought "what will happen when the vague concept of the Internet-of-Things becomes a reality" I can't stop. I always loved Subarus, but now I want one.

I don't think there's a funniest submission competition, but I marked it as a favorite.

Along the same lines, I had a hell of a time tracking down the reason my washroom GFI (ground fault interrupter) tripped on random occasions; i.e., the electric outlet would lose power and need to be reset.

It turned out that an iPhone receiving a phone call tripped it -- even before it starts to ring! Making a phone call didn't do anything. Here's a 13-second video:


I'd love to hear comments about the possible cause.

I can often tell that I'm about to receive a text message because my poorly shielded computer speakers will start buzzing. I assume it's caused by a transmission from my phone's radio inducing a current in the amplification circuit.

I would guess this is what's happening with your GFI. Even though you're receiving the call, your phone is probably transmitting too (sending back the equivalent of an ACK or something). The current induced causes a difference between hot and neutral and the GFI trips. It's surprising that it can induce a strong enough current! I'm not sure what wattage cell phone radios operate at.

Edit: Ah missed the detail about outgoing calls not causing it. That is very strange! Perhaps a cell phone engineer can shed some light on that!

I’m guessing car manufacturers have caught onto this. I drove a year 2000 car whose speakers would know I was about to receive a text/call several seconds before receiving it. I don’t think I’ve been in a model later than 2008 that’s had this problem. The noise, like the AOL dialup modem beeps, are one of those things that become cemented in your brain and immediately recall themselves as soon as you think about them. I heard the short succession of beep patterns in my head as I read your comment.

Makes a guy nostalgic for beach summers when the boombox would overlay that because someone left their phone to close to it.

Yep that’s it. So it wasn’t the cars then, it was the networks being updated.

That, and possibly that newer networks work on different frequencies.

It's not that they use different frequencies (in a lot of places, they've actually recycled GSM frequencies for increased LTE bandwidth) but that they use a different form of modulation (than TDMA) that doesn't cause the same interference

I remember old feature phones which had a fancy light on the back, which started blinking whenever a call was about to come through. Was a pretty nifty feature when you were expecting calls ['twas a time when I used to give "missed calls" for a callback].

My friend's chinese motorcycle had this light built in on the gas tank. It's really helpful because you can't hear your phone ringing/vibrating while riding. AFAIK, this stopped working after transition to 3G.

Before UMTS came online and brought higher frequencies etc, i seem to recall novelty shops had a rack of objects one could attach to a phone. These would all light up when a call came in. There was apparently enough juice in the signal that the antenna in the object could drive a LED.

Yup. It doesn't take much to make an SMT LED shine - just a milliamp or two, and an interesting property of that kind of inductive coupling is that, up to a limit, you can couple a higher voltage out of a given signal by increasing the number of turns in your winding. And if you couple out more than the forward voltage of your LED junctions, you can convert the surplus into enough current to visibly light the LEDs as they conduct. So with the right kind of boost circuit - in this application probably just an inductor, although I could be wrong here, analog isn't my forte - driving the LEDs, and a bare-die CMOS shift register that sips a few microamperes for the animation, you can pretty easily produce the kinds of effects I remember seeing back in the before time too - and still miss to this day!

RFID works by the same principle, incidentally - in this case, the energizing signal comes from a primary winding in the reader housing, and the secondary in the card powers a little CMOS chip that in cheaper models just modulates the voltage drop over the winding to return a constant code, and in more expensive models receives a challenge nonce signaled by the card reader and modulates the winding to return an encrypted response. It's a really interesting application, and an impressive but often overlooked early example of "IoT" style smarts done well.

I would guess it's probably your phone's speaker. As the call coming in, the phone fires up the speaker for ringing. The speaker induces a current.

GFCI works by detecting the difference in the current flowing between the hot wire and the neutral wire. It needs to work very fast (to avoid the human touching the wire getting electrocuted) so any slight difference in current would trip it off. The current induce by your phone's speaker probably causes enough difference in the current to trip it off.

You can run an experiment by turning off your phone's speaker for incoming call. See if the speaker is the culprit.

The timing sounds like RF interference. I worked in TV a while back, and we were not allowed to have any cell phones (even silenced) on set - they would introduce this crackling sound into lightly-shielded cables near them. The interference would kick in about a second or two before the ringing started, because there's probably some handshake/setup before the receiving phone decides it's actually an incoming call.

In that case too, sending calls didn't trigger the interference, and neither did picking up the received call.

My layman understanding of the old GSM network is that cells have a control channel that is used to set up calls (and initially also transfer SMS, before it became popular enough to DOS the cells) and then a bunch of channels for handling the actual calls.

It may well be that the control channel's initial "wakeup" transmission is done at a very high power to ensure the phone receives it clearly, and then after some back and forth the two adjust their power levels and move to a different channel for the actual call.

Interesting! Would explain why sending a call doesn't push out as much power.

I do the same thing in recording studios. You have to turn off your phone completely. Nothing worse than ruining a good take when you receive a call.

Does it happen with any other kinds of phones? Like can a landline or Android phone also trip your GFI when it receives a call?

The same thing happens with a Motorola RAZR V3 GSM quad-band cell phone (a flip phone). I have that on video as well though I didn't upload it. I haven't tested any other phones.

Probably GSM. They do that, make interference before the phone rings. Put it by some computer speakers turned on full blast with no sound playing. You'll here the GSM morse code.

I don’t know why, but my thought was the same as the third most voted comment in the thread too. The collision avoidance system, which I would have guessed was ultrasound, but the guy on reddit says it’s microwave. Either way, that could be picked up by some kind of sensors in a house alarm system.

We live in a crazy world.

I don't know, I would tend to side with the theory that the car engine sound at the specific RPM and power output matches the resonance frequency of one of the house windows. Resonance can creep up in many phenomena.

But the engine speed doesn't change until you lift the clutch. So if this were due to the RPM, putting it in reverse while stationary surely wouldn't do anything in particular.

If it’s an automatic, putting into reverse will change the engine RPM.

Fuel mixture changes as the engine heats up, changing the sound

Not in my opinion because this would have been a problem before with other cars and alarms. Or motorbikes.

Without knowing the details of the alarm system it is hard to have an educated guess.

I've owned a number of Subarus and let me tell you, even the non-performance models have a way of shaking things inside the house that you wouldn't believe until you experience it. My STI was capable of being loud, but oddly enough it was my wife's Outback (nearly silent if you stood next to it) that would shake pictures on the walls and make them start tapping.

Very true. My '13 WRX shakes pictures when I start it up in the garage, I have to immediately pull into the street so I don't piss anyone off while getting Google Maps and Spotify set up before I drive.

Motion detectors with microwave, especially residential sensors, don't use it as the sole detection method. It's always paired with passive infrared. Microwave interference doesn't really make any sense because he'd have to be tripping the infrared and microwave source at the same time.

Source: I wrote firmware for microwave/PIR motion detectors for a few years.

His WRX doesn't have backup sensors.

It could have backup sensors.

Rear cross detection and blind-spot detection is an option package.

This allows my car (2016 WRX Limited) to warn me about cars flying by when I am backing up out of a parking spot for example.

I have that on my Mazda 3 and it's absolutely brilliant. The range and sensitivity of that system is rather amazing.

FYI car makers are starting to collect data from connected cars using their ultrasonic sensors for collision avoidance, among other sensors. You can indeed use them to map surroundings fairly accurately.

Mine isn't connected but, yep, could certainly see how that'd work. Whilst no fancy auto pilot yet, the AEB and radar cruise are very nice things to have in a car.

I have 2014 3. This system has spoiled me. If my next car doesn't have something similar, I'll probably crash it pulling out of dealership.

Yep, same model / year as mine. 2.5l MT Astina. Great car!

The reverse lights triggering motion detection and engine/transmission vibration both seem plausible too.

Reminds me of this story where a car was 'allergic' to vanilla ice cream: https://news.ycombinator.com/item?id=13347852

There's also the case where an email seemingly had a physical distance limit : https://www.ibiblio.org/harris/500milemail.html

The curse of the 500 mile email and the car that won't start because it's allergic to vanilla icecream. ;)

- https://www.ibiblio.org/harris/500milemail.html

- http://www.cgl.uwaterloo.ca/smann/IceCream/humor.html

Used to set off car alarms all the time when I had ‘quite hotted up’ Type R Integra years ago, never house alarms though I think.

I’m willing to be the guy/gal next door has those broken window alarm strips installed, one part of the strip is loose and when the cars RPM drops as the clutch is let out while in reverse it slightly vibrates the window causing the contact to short (or break) and thus the house alarm goes off.

Good fun :)

Very likely. My neighbors son has a loud as hell car and it definitely rattles my windows even when in idle.

Last year a co-worker frantically came over to tell me that text was disappearing from her computer screen. I walked over to her desk and watched as she began to type an email. Sure enough, the characters she entered went away one at a time. I glanced down at the desk and gently lifted a headset that was resting on the "delete" key of the keyboard.

What I would pay to hear this on Car Talk. Sigh.

sigh. I know...

Skip to 18:50 and listen on for couple minutes.

Love the caller complaining about his brother in law.


That's great, and thanks, I had no idea about the implications of the oil light.

I really miss his infectious laugh. He saw humor in everything.

Click'n'Clack4eva. You're absolutely right, they'd have had an absolute field day with this.

This sounds like the kind of thing they should mention on ATP (http://atp.fm/ - nice podcast if you're into tech, especially Apple)

This comment made me laugh:

> Maybe you neighbor is setting off his alarm on purpose just to mess with you haha!

That would be some next level mindfuckery

Reminds me of when my dad had strewn ham radio antennae between trees in our backyard when I was a kid. For a few days, any time he started doing his Morse code, the neighbor's garage door would start going up and down.

Makes me think of early days of wireless keyboard, where the same model would always broadcast on the same frequency.

Made for some fun times at LAN parties etc.

Even read about a pair of keyboard that managed to reach several kilometers, even though the locations had line of sight blocked by a hillside.

Added to my "Stories from the Internet" collection :) https://dbrgn.ch/stories-from-the-internet.html

Nice, I love reading about these things.

Two related things-that-should-not-be-related bugs that I have encountered:

The WiFi on my girlfriend's laptop would fail when an HDMI cable was plugged into the laptop. Changing the channel on the router "fixed" it but we never could figure out the ultimate cause.

I can pause my Roku box using the Kodi remote app on my phone. This occurred when I inadvertently used the wrong remote to pause the Roku. It appears only to work if the Raspberry Pi running Kodi has gone into some sort of standby mode, possibly making the Kodi remote app send a wake signal which is interpreted by Roku as the pause signal.

No engineer, but i suspect the WIFI and hdmi stuff is RF related. Someone did a poor job on the laptop wiring and the HDMI is leaking noise into the WIFI antenna or something.

Seem to recall reading about similar issues related to WIFI and USB3.

As for the remote app stuff, i guess it's time to break out the packet sniffer.

My first thought was parking assistance which might trigger a sensor in the other house.

I drive a modified car, this is obviously the glass break sensors in the house. My car sets the sensors of other aftermarket car alarms off as I drive around because of the exhaust frequency. I imagine the same thing is happening here.

I didn't realize anyone would actually admit to driving such a public nuisance.

Not only are you being rude, you're providing no value to the conversation.

To me (an electronics engineer) it sounds like your neighbor's alarm did not pass EMC immunity tests quite ok... and at the same time the car's tests were passed with way too thin margin.

Or it could be that one of the alarm inputs is in high impedance, but then it should trigger to way more than just putting a car in reverse. Little bit of site surveying with portable spectrum analyzer may reveal something. Or playing around with wide-band emitters -- which may be illegal.

Then again -- it may be something else. Good hint would be to know what sensor is triggered exactly. Usually alarm control panels tell that.

Yeah, no I don't think we're ready for the internet of things.

I have this weird "turn on your laptop and your phone cannot see the wi-fi anymore" bug, or whatever this is. I've tested this with different phones, same issue. So, I'm turning on my phone wi-fi and it all works well. As soon as I start my laptop, the wi-fi goes off, it is not seen by my phone. The laptop is cable-connected. Sometimes all is fine so this is kinda random. Maybe on cloudy days it works (as remyp says of his ipads), haven't checked.

Sounds like your laptop's wifi module is introducing unwanted interference.

My brother had a 1991 Ford Mustang 5.0 with a flowmaster 3 inch exhaust system (no cats). It would set off alarms at a specific RPM in 2nd gear (under slight load). He enjoyed annoying people with it (my brother was a hardcore car guy).

View this YouTube video to get a good idea of how the car sounded (my brother's was a bit louder): https://youtu.be/cNWv5WpamPc

Interestingly, I used to have a 433MHz wireless doorbell (a "1byOne", specifically) that would spuriously chime every time a specific one of my neighbour's cars set off.

I assumed it was interference from some sort of PIR motion detector transmitting a signal to say it saw some motion, but I suppose it could conceivably have been caused by the car going into reverse.

I never debugged it, I just threw the doorbell away and bought another.

Garage door openers frequently operate at 433MHz, very likely your neighbor was hitting the button as they left?

Good thought, but they don't have a garage.

This reminds me of "emails won't send beyond 200 miles".

If his garage is angled, he could try neutralling out to the street before starting the car.

This makes me wonder if anyone has thought to add microphones yet to the array of sensors an autonomous car uses. Things like "my neighbors alarm keeps going off when I go into reverse" and "there is an ambulance somewhere I cannot see yet" sound mighty useful (well, at least the latter example), but very hard to incorporate.

I currently have an issue with my iMac (also happened with the MBP) and iphone 8 (also happened with the previous iPhone 5S) that if I have bluetooth enabled on my phone and unlock it... my bluetooth mouse stops responding on the iMac. Interestingly my phone and iMac are not paired and nor is the mouse and phone.

Very frustrating

I used to have a Mazda whose alarm went off every time I used particular 2.4ghz remote control within 10ft of it.

I've owned two WRXes (05 and 07) and stock, they do have quite a lot of bass. :-P I usually take the train to work every morning, so thankfully I haven't triggered a neighbors car alarm. Yet considering the sound that comes out of the stock muffler, I can see how this happens.

Some time ago I posted a weird issue I noticed with my neighbour. HN solved the mistery in minutes... =)


Yours remind me when I was also a radio aficionado many years ago, one night my upstairs neighbor called me because each time I pressed the button to talk, my voice would come out from her TV. I was basically ruining her favorite soap opera!

I'm having a waking dream of Click and Clack (RIP) discussing the phenomenon.

I half expected this to be another IoT thing. The car broadcasting some form of wireless signal when it switches gears for some app integration, and the alarm picking that up.

Not particularly mysterious, but I got quite a jump one day when I keyed up my 50w VHF mobile in the garage and instanly every single fire alarm in my house went off.

Maybe the car owner has some sort of parking sensor, uses radio and thus interferes with neighbor’s house alarm system?

Maybe the rear lights has something to do with it, could be a faulty light oscillator for led if you are using one

Sounds like a great question for Car Talk!

Reddit is literally leaking

Someone explained it properly in the reddit thread, it's the exhaust generating noise while driving in reverse (only happens in the morning when cold and at specific RPM, exhaust generates a specific frequency which vibrates the windows and triggers the alarm).

> Someone explained it properly

That's a hypothesis, a very good hypothesis, but the Reddit thread and Hacker News offer many other reasonable-sounding hypotheses. I can't tell you the number of times I've tracked down a bug or other type of malfunction where I was 100% sure of the cause since my hypothesis made so much sense, but it turned out to be wrong. It was something else.

Alternative hypothesis, for the sake of example -

Someone's just really be into practical jokes. Possibly the neighbor whose alarm keeps going off, or possibly a third-party who found an easy way to trigger the alarm.

But, my first thought on this thing triggering when he backs up is a rear-view sensor that uses a projection to get data. Apparently the 2018 version of his car has radar sensors that go off when backing up (https://www.subaru.com/engineering/safety.html):

> Rear Cross-Traffic Alert uses radar sensors to help warn you of traffic approaching from the side as you are backing up, utilizing an audible warning and flashing visual indicators in your side mirrors and Rear-Vision Camera display

I wonder if backing up would set off other people's radar detectors.

Reminds me of "Trolling for Taillights"!


Seems like the neighbors home security system should have a log of which sensor is tripped. Once you know that it should be pretty easy to figure out what is going on.

It's the future.

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