Q: Modding piezo in smoke detector - changing FREQ, AMP, or

[Mr. INTJ]

Hi,

I have a problem - our dog has developed a phobia of smoke alarm
beeps. She's always been afraid during thunderstorms, but this smoke
detector thing is a whole new level of abject terror for her. It's
gotten to the point where if one of them even pips briefly (due to low
battery), she trembles all over, and tries to burrow under furniture
(usually at some ungodly hour of the morning).

OK, so I did what any responsible adult would do... I disconnected
every single smoke detector in the house. It was only supposed to be
short-term, but behavior mod. on our dog was $$$ and ineffective, and
after several months, I still don't have a solution.

MORE INFO:

Not all beeps are created equal - only certain combinations of
frequency, amplitude (and possibly waveform) strike terror in her. I'm
a software guy by trade, but I play an EE in my spare time, so when
this first started happening, I opened one of the smoke detectors and
examined it - hoping there'd be a simple R-C circuit that I could
modify in some way to alter things enough that it wouldn't freak out
the dog.

Of course there's a big piezo disc in there that's responsible for the
piercing beeps, and it was put together in such a way that I concluded
at the time that the pitch was tied to the physical dimensions of the
disc itself (a kind of mechanical buzzer), vs. the signal being
applied... does this sound possible, or was I sleep-deprived that day?

Can anyone shed more light on this?

Thanks.

Mr. INTJ
San Diego, CA

 

[Jasen Betts]

On 2008-08-18, christofire <christofire@btinternet.com> wrote:

Such piezo sounders usually have the disc (metal disc with a layer of piezo
material covered with a layer of metallisation) mounted in a small closed
plastic cylinder with a hole which acts as a Helmholtz resonator.

so he could cut and lengthen the tube (maybe use PVC pipe) and get a lower frequency ?

Bye.
Jasen

 

[Rich Webb]

On Mon, 18 Aug 2008 09:04:37 -0400, "Tom Biasi"
<tombiasi***@optonline.net> wrote:

My suggestion is to try different brands of smoke detectors. As soon as you
modify a life safety device your insurance company will not pay any damage
due to smoke of fire.
And you may die.

Modern detectors use a single chip. Everything is designed already. The
piezo is a resonant device that needs the proper pulse to meet the specs on
audible output for home detectors.
Don't mess with it.

There are options like
http://www.amazon.com/Kid-Smart-10012VSD-KidSmart-Detector/dp/B000E6JPJC
which is one of several smoke detectors that use a voice (one's own, in
this case) as the alarm.

--
Rich Webb Norfolk, VA

 

[Mr. INTJ]

On Aug 18, 6:04 am, "Tom Biasi" <tombiasi...@optonline.net> wrote:

"Mr. INTJ" <mr.i...@gmail.com> wrote in message

news:f4d5ac03-925b-4065-ab62-bd12d1bcac27@j1g2000prb.googlegroups.com...



Hi,

I have a problem - our dog has developed a phobia of smoke alarm
beeps. She's always been afraid during thunderstorms, but this smoke
detector thing is a whole new level of abject terror for her. It's
gotten to the point where if one of them even pips briefly (due to low
battery), she trembles all over, and tries to burrow under furniture
(usually at some ungodly hour of the morning).

OK, so I did what any responsible adult would do... I disconnected
every single smoke detector in the house. It was only supposed to be
short-term, but behavior mod. on our dog was $$$ and ineffective, and
after several months, I still don't have a solution.

MORE INFO:

Not all beeps are created equal - only certain combinations of
frequency, amplitude (and possibly waveform) strike terror in her. I'm
a software guy by trade, but I play an EE in my spare time, so when
this first started happening, I opened one of the smoke detectors and
examined it - hoping there'd be a simple R-C circuit that I could
modify in some way to alter things enough that it wouldn't freak out
the dog.

Of course there's a big piezo disc in there that's responsible for the
piercing beeps, and it was put together in such a way that I concluded
at the time that the pitch was tied to the physical dimensions of the
disc itself (a kind of mechanical buzzer), vs. the signal being
applied... does this sound possible, or was I sleep-deprived that day?

Can anyone shed more light on this?

Thanks.

Mr. INTJ
San Diego, CA

My suggestion is to try different brands of smoke detectors. As soon as you
modify a life safety device your insurance company will not pay any damage
due to smoke of fire.
And you may die.

Modern detectors use a single chip. Everything is designed already. The
piezo is a resonant device that needs the proper pulse to meet the specs on
audible output for home detectors.
Don't mess with it.

Tom

Good point about the insurance aspect - hadn't considered that (i.e.
dying is OK, but not getting reimbursed simply won't do).

OK, so I'll focus my efforts on smoke alarms with a different sounding
alarm.

 

[Yukio YANO]

Mr. INTJ wrote:

Hi,

I have a problem - our dog has developed a phobia of smoke alarm
beeps. She's always been afraid during thunderstorms, but this smoke
detector thing is a whole new level of abject terror for her. It's
gotten to the point where if one of them even pips briefly (due to low
battery), she trembles all over, and tries to burrow under furniture
(usually at some ungodly hour of the morning).

OK, so I did what any responsible adult would do... I disconnected
every single smoke detector in the house. It was only supposed to be
short-term, but behavior mod. on our dog was $$$ and ineffective, and
after several months, I still don't have a solution.

MORE INFO:

Not all beeps are created equal - only certain combinations of
frequency, amplitude (and possibly waveform) strike terror in her. I'm
a software guy by trade, but I play an EE in my spare time, so when
this first started happening, I opened one of the smoke detectors and
examined it - hoping there'd be a simple R-C circuit that I could
modify in some way to alter things enough that it wouldn't freak out
the dog.

Of course there's a big piezo disc in there that's responsible for the
piercing beeps, and it was put together in such a way that I concluded
at the time that the pitch was tied to the physical dimensions of the
disc itself (a kind of mechanical buzzer), vs. the signal being
applied... does this sound possible, or was I sleep-deprived that day?

Can anyone shed more light on this?

Thanks.

Mr. INTJ
San Diego, CA
I have a different proposal. In my household the Smoke Alarm usually

fires up when Dinner is almost ready ! The poor Dog is just going to
have to learn that the smoke alarm is also FEEDING TIME ! The trick now
becomes, "How to reliably trigger the smoke alarm at feeding time, so
the dog listens for the Smoke Detector. My dog tells me!, when it is
5:00 pm and 11:00pm.

Yukio YANO

 

[Mr. INTJ]

On Aug 18, 10:33 pm, Yukio YANO <y...@shaw.ca> wrote:

Mr. INTJ wrote:
Hi,

I have a problem - our dog has developed a phobia of smoke alarm
beeps. She's always been afraid during thunderstorms, but this smoke
detector thing is a whole new level of abject terror for her. It's
gotten to the point where if one of them even pips briefly (due to low
battery), she trembles all over, and tries to burrow under furniture
(usually at some ungodly hour of the morning).

OK, so I did what any responsible adult would do... I disconnected
every single smoke detector in the house. It was only supposed to be
short-term, but behavior mod. on our dog was $$$ and ineffective, and
after several months, I still don't have a solution.

MORE INFO:

Not all beeps are created equal - only certain combinations of
frequency, amplitude (and possibly waveform) strike terror in her. I'm
a software guy by trade, but I play an EE in my spare time, so when
this first started happening, I opened one of the smoke detectors and
examined it - hoping there'd be a simple R-C circuit that I could
modify in some way to alter things enough that it wouldn't freak out
the dog.

Of course there's a big piezo disc in there that's responsible for the
piercing beeps, and it was put together in such a way that I concluded
at the time that the pitch was tied to the physical dimensions of the
disc itself (a kind of mechanical buzzer), vs. the signal being
applied... does this sound possible, or was I sleep-deprived that day?

Can anyone shed more light on this?

Thanks.

Mr. INTJ
San Diego, CA

  I have a different proposal. In my household the Smoke Alarm usually
fires up when Dinner is almost ready ! The poor Dog is just going to
have to learn that the smoke alarm is also FEEDING TIME ! The trick now
becomes, "How to reliably trigger the smoke alarm at feeding time, so
the dog listens for the Smoke Detector. My dog tells me!,  when it is
5:00 pm and 11:00pm.

Yukio YANO

Yeah, I tried the conditioning thing - but it's almost a physical fear
she goes through. After a few days, I had to quit - I just couldn't
keep doing it to her.