1. Home
  2. Embedded Programming
  3. Stupid design decisions

Stupid design decisions

The following is more a vent than anything really constructive, but...

So for the last four days (yes, I got called in New Years day afternoon), something has been beeping in the computer room.

Let me rephrase that. A proper beep would have likely been little more than an annoyance. No, this was a single, fraction of a second, fairly high frequency, not very loud, chirp, repeated at odd intervals, typically in the 5-20 minute range, although with excursions to the 30s and 2-hour-plus ranges. And did I mention, the volume was not particularly consistent? And it was high enough pitched that half the people trying to help couldn't hear it at all.

IOW, a signal with very poor directionality, in a room with a couple of dozen computers, other electronics, A/C, and whatnot contributing tons of background noise.

I have rarely in my life been so frustrated, as I have been trying to locate that dang* chirp.

As it turns out, there was a device that had an embedded fan (1.5 inch muffin), and a temperature sensor. The fan bearing was going bad (in a quiet area, removed from the outer enclosure, the bad bearing was audible, but not at all in the computer room) and cooling was impacted. The only sign of the overheat was that dang chirp from a little magnetic buzzer (an AX-1212-LF, if anyone cares). Somewhat amusingly, this is a device rated for 8-12V, and there's nothing more than 5V headed into the portion of the device where the buzzer was (and there are mechanically identical 5V and 3V devices in the product line - AX-1205, AX-1203, for example). That probably explains part of both the volume and frequency (the device is supposed to be producing ~2300Hz, but it was at least in the 5kHz range) issues. The apparently minimal length of pulse used to trigger it likely explains the rest. And did I mention that this buzzer is inside a mostly enclosed component inside the case of the device?

And no, the overheat does not appear to be reported anywhere (despite considerable chat between the device and the host system).

I understand the need to not make alarms excessively obnoxious (and there is a handy little "BUZZER DISABLE" jumper next to the buzzer), but making them so hard to hear is just absurd. Clearly no one ever tried listening to this in any real environment. There are so many ways this could have been better. A simple series of chirps at each alarm would have made this infinitely easier to trace. Perhaps having it repeat at a reasonable interval. Or a reasonable frequency and duration. They went to all this trouble to monitor temperatures, and then have an alarm, and then made it almost unusable.

Took about 15 minutes to swap in a spare (less than half of which was screwdriver time). Now to find a replacement fan to refurb the old unit.

Ah well. My apologies for the rant. Back to the regularly scheduled program...

*much stronger word removed
Reply to
Robert Wessel
Loading thread data ...

I feel your pain. I've always thought the high pitched beep is a load of crap to begin with. Surely there are other ways to make a less annoying and more easily detected/noticed sound. When I have a piece of gear in a bag making noise, good luck figuring out which bag and which piece of gear it is. When it is such an intermittent thing like a low battery warning, well, you only get so long to locate it before it just quits. Or worse, figuring out which of the two smoke detectors are emitting a once an hour, single chirp! One is just above the other, two floors with an open balcony. That drove me nuts for several nights.

Yeah, they really should give a bit more thought to the use cases for such alerts.

--

Rick C
Reply to
rickman

Ah, you wanted to know _where_ the problem was. That's what the smoke and flames are for...

--
Grant Edwards               grant.b.edwards        Yow! FOOLED you!  Absorb 
                                  at               EGO SHATTERING impulse 
                              gmail.com            rays, polyester poltroon!!
Reply to
Grant Edwards

The incorrect voltage spec may have been the brainchild of someone in procurement, or of an incompetent component engineer.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com 

I'm looking for work -- see my website!
Reply to
Tim Wescott

If you have a good infrared camera around (not /that/ unlikely, in this newsgroup) then it can be useful to spot problems when they are beeping, but not yet smoking.

Reply to
David Brown

If you are just trying to find a hot spot, a camera is a bit of overkill. A handheld remote temp sensor is great. I tried it last

have used a few more letters so they could say "F****** Cold".

--

Rick C
Reply to
rickman

I use the same technique. And it is "f****** cold" here, too; -11 C last night and was - and is expected to - be worse over the next few days. Those IR thermometers are cheap nowadays, mine cost me about $300 back in the day (nearly 20 years ago....), I got it to control the PCB baking temp when I started using BGA-s. Still in use for that, and for finding cold spots on windows, doors and walls (to detect warmth leaks), to measure tea temp (55 C is the highest tolerable to start drinking, how many people knew that one :), beer temp during the summer (target being around 5C is probably known by most people...) etc etc.

Dimiter

Reply to
Dimiter_Popoff

I don't know where you are, but I thought most of Europe drank warm beer. I know they do in England. A friend was working here and couldn't stand drinking cold beer. He'd ask the bartender to find a case in the hallway that wasn't refrigerated.

--

Rick C
Reply to
rickman

Oh no, this is not the case in Europe; I am surprised about England, never been there. But where I have lived, in Bulgaria and Germany, and I think all the countries between, beer is supposed to be around 5C. In fact in Germany I have been told at the bar (must have been in the morning) "we don't have beer yet, it is still warm".

Dimiter

Reply to
Dimiter_Popoff

Not 'warm', but at cellar temperature, around 13C, and only for ales and sometimes ciders. That's in the UK. By and large, the rest of Europe drinks cold lager.

SWMBO isn't a Brit, and one of her visiting US cousin was put off by her telling him that our beer was 'warm'. It isn't, he missed out.

Cheers

--
Clive
Reply to
Clive Arthur

That will depend on the type of beer, as well who is drinking it. For more "solid" beers, it is common to have them a little warmer than fridge temperature (ideally right from the barrel - cooler than room temperature, but not cold). Basically, your sense of taste does not work well on things that are fridge temperature. So when you are drinking lager for refreshment, cold is good - but when you are drinking good stuff for the taste, it needs to be warmer to appreciate it.

See section 10 in the letter here:

Reply to
David Brown

In this case it would not have helped. The failed fan bearing and overheat (and the darn buzzer) was in a unit installed inside the chassis of a larger device. The outer device had no cooling issues, and so would have shown no external hotspots. The inner device would not have been producing any more heat than normal, so the thermal load it passed to the outer device would have been unchanged (the route the heat took out of the inner device would have changed).

Reply to
Robert Wessel

You all read his story. Mine is on the consumer side. It's short, but a little expensive (cost me about $100 bucks). So this is my story regarding locating a beeping source. 8^)

So a few years ago I replaced all the smoke detectors in the house. they were WELL past their useful life (which the manufacturer says is ten years). Then at Halloween, I did my annual battery replacement. I also replaced the battery in a separate CO detector in the basement.

All is fine and dandy, that is until a few weeks ago.

We started hearing an intermittent chirp. Clearly the battery low signal. But I just replaced those with fresh ones! Oh well, can't always be sure even a new battery is fully charged.

Get a new battery and replace it in the smoke detector.

Seems okay, but not long after... chirp!

Even standing right under the detector I cannot tell the direction. But maybe it was the CO detector. Replace its battery again.

Seems okay, but not long after... chirp!

Okay, I test by removing the CO detector (it is a plugin unit) to the upstairs, but still here the chirp downstairs.

Off to the hardware store. I am a little pissed because the Smoke detector should last 10 years and this was 3 years old. But they are cheap (

Reply to
Ed Prochak

Yeah, I spent some time the other day chasing down what was obviously an "alarm clock". Apparently, only rings for a minute or two, then self-resets. So, if you're not in the garage (which is where it was, sitting in a pile of items to be recycled) when it goes off, you'd never know!

I figure I've just saved the folks at the recycling plant a hassle or two!

People KNOW where their smoke detectors are located. The goal of the alarm in the detector is to be as loud and annoying as possible.

Of course! You can buy detectors with non-replaceable batteries (the entire detector is discarded after 10 years)

Yup. It also gives you a reminder to test the thing and remind yourself what it sounds like when it sounds off (ours are combination units so the alarms for smoke and Co are different). As well as testing the interconnect -- to make sure ALL sound when *any* sounds!

A $60 leson you will undoubtedly not need to repeat! :>

Reply to
Don Y

The problem isn't that I don't know where the smoke detectors are. The problem is I don't know which of the half-dozen of them is upset.

This could be solved easily with an LED...

--
Grant Edwards               grant.b.edwards        Yow! I think my career 
                                  at               is ruined! 
                              gmail.com
Reply to
Grant Edwards

One of the LEDs on each of our detectors "chirps" coincident with the battery test. I think the actual circuitry "hibernates" most of the time and only powers up, runs the test (for smoke/CO/battery) then powers down, again.

So, stand under the detector and listen for chirp -- verify it coincides with LED flash... or, move on to next detector!

[I think there is also a way to determine which detector is signalling the alarm (when one is detected) so you don't have to unplug each of them to locate the offender]
Reply to
Don Y

If they only chirp once every 15-20 minutes, that can be frustrating.

And they always _start_ the chirping in the middle of the night....

--
Grant Edwards               grant.b.edwards        Yow! But they went to MARS 
                                  at               around 1953!! 
                              gmail.com
Reply to
Grant Edwards

Am 30.01.2017 um 21:55 schrieb Grant Edwards:

That stops being a problem once you realize that it doesn't really matter which of them is the first to go. As soon as the first of them complains, you replace _all_ their batteries, preferably with a batch of same-model batteries, from the same shop, with equal date stamps.

After the first round of this, all the batteries are the same type and age, so when the first one goes, all the others will likely go soon enough after that they best be replaced right away, too.

Or to put it into terms more applicable to c.a.e.: globally forced synchronization avoids the problems of asynchronous, spatially distributed event sources.

Reply to
Hans-Bernhard Bröker

The last couple I installed have added voice to all the signals (so "BEEP! BEEP! BEEP! FIRE! FIRE! FIRE!" or "BEEP! BEEP! BEEP! CARBON MONOXIDE!") That extends to the warnings as well ("chirp! low battery!"). Which is a significant improvement.

Most modern detectors also take themselves out of service after their rated lifespan (most seem to be rated for 7-10 years these days). In the prior generation this resulted in more chirps, but the new ones are supposed to announce that as well.

Reply to
Robert Wessel

I had TWO detectors: one smoke, one CO, located about 12 feet apart with the furnace in between and a shelf in between. And I could not tell which was chhirping!

I said NOTHING about the alarm. Comon Don you are better than that.

You couldn't do that twenty years ago when that old detctor was installed.

yes our smoke detectors are interconnected, which is another reason I kept the combo smoke/CO detector. And knowing the old CO detector was likely still okay, I put it in the garage. (I don't use my fireplace much any more.)

I hope so, but my brain gets so overloaded from work wsometimes that I cannot guarantee it. 8^)

Enjoy, ed

Reply to
Ed Prochak

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.