Interesting gas sensor -business-

In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
About 30 USD back then, runs on 12V a wallwart that came with it, and has a VERY LOAD beep if it detects even a slight bit of gas.

So yesterday. while working upstairs with the soldering iron on some audio stuff, I heard a load beeeeeeep
continuous beep.
Thought first it was one of the fire detectors (several in the house),
went downstairs and found that gas detector.
Did not smell any gas though..
Unplugged it, took it outside in the fresh air, powered it, and it beeped again
So looks defective...

Today I was really curious what was wrong with it, checked the 12 V wallwart, was OK, used scope, no ripple.
Opened it up and looked inside at the sensor PCB..
5 or 6 chips, a bridge rectifier, some chips with no number or number removed...
Measured some things. 3.3 V regulator OK, seems all OK, must be the sensor.
Then I spotted the microscopic small text on the back:
it says : Buy a new one after 5 years
then in even smaller text
production date 15 5 2018
replacement date 15 5 2023
I looked for a battery backup or if they used a timer.... No.
I think this is crooked, a new one now is about 29 Euro / dollar:
https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p168047.html
So when I bought it it was already 1 year old!

So I won't play and will use one of these:
https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
3 Euro 50 cents
10 times cheaper, will hang it on an ADC channel of some other ethernet connected sensor I build...
https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
still space for a second sensor.
Or maybe I will just integrate that into the existing housing of the old one...
But what a business model?
Sell a new car every few years if your headlights fail?

On 9/26/2023 12:00 PM, Jan Panteltje wrote:
> Interesting gas sensor -business-
>
> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
> About 30 USD back then, runs on 12V a wallwart that came with it, and has a VERY LOAD beep if it detects even a slight bit of gas.
>
> So yesterday. while working upstairs with the soldering iron on some audio stuff, I heard a load beeeeeeep
> continuous beep.
> Thought first it was one of the fire detectors (several in the house),
> went downstairs and found that gas detector.
> Did not smell any gas though..
> Unplugged it, took it outside in the fresh air, powered it, and it beeped again
> So looks defective...
>
> Today I was really curious what was wrong with it, checked the 12 V wallwart, was OK, used scope, no ripple.
> Opened it up and looked inside at the sensor PCB..
> 5 or 6 chips, a bridge rectifier, some chips with no number or number removed...
> Measured some things. 3.3 V regulator OK, seems all OK, must be the sensor.
> Then I spotted the microscopic small text on the back:
> it says : Buy a new one after 5 years
> then in even smaller text
> production date 15 5 2018
> replacement date 15 5 2023
> I looked for a battery backup or if they used a timer.... No.
> I think this is crooked, a new one now is about 29 Euro / dollar:
> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p168047.html
> So when I bought it it was already 1 year old!
>
> So I won't play and will use one of these:
> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
> 3 Euro 50 cents
> 10 times cheaper, will hang it on an ADC channel of some other ethernet connected sensor I build...
> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
> still space for a second sensor.
> Or maybe I will just integrate that into the existing housing of the old one...
> But what a business model?
> Sell a new car every few years if your headlights fail?

Jan,

Gas Testers or Sniffers have an approximate life span of about 7 years
depending on manufacture. In the circuitry there is a counter that
when the programmed max is reached the unit QUITS!! DONE!! EXPIRES!!

YUP time to buy another one!!

Have a better day!!

Les

On 2023-09-26, ABLE1 wrote:
> On 9/26/2023 12:00 PM, Jan Panteltje wrote:
>> it says : Buy a new one after 5 years
>> then in even smaller text
>> production date 15 5 2018
>> replacement date 15 5 2023
>> [...]
> Jan,
>
> Gas Testers or Sniffers have an approximate life span of about 7 years
> depending on manufacture. In the circuitry there is a counter that
> when the programmed max is reached the unit QUITS!! DONE!! EXPIRES!!

Yep, same with (modern) smoke detectors. The older ones were also
useless after 7-10 years, but didn't make a big fuss about it.

Though the ones i recently installed have something that keeps the
detector "fresh" (for lack of a better word) until you first turn it on.
Then it's self-contained for 10y (no user-replaceable parts, etc) with a
one-way permanent off switch.

--
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860

On Tuesday, September 26, 2023 at 12:00:35 PM UTC-4, Jan Panteltje wrote:
> Interesting gas sensor -business-
>
> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
> About 30 USD back then, runs on 12V a wallwart that came with it, and has a VERY LOAD beep if it detects even a slight bit of gas.
>
> So yesterday. while working upstairs with the soldering iron on some audio stuff, I heard a load beeeeeeep
> continuous beep.
> Thought first it was one of the fire detectors (several in the house),
> went downstairs and found that gas detector.
> Did not smell any gas though..
> Unplugged it, took it outside in the fresh air, powered it, and it beeped again
> So looks defective...
>
> Today I was really curious what was wrong with it, checked the 12 V wallwart, was OK, used scope, no ripple.
> Opened it up and looked inside at the sensor PCB..
> 5 or 6 chips, a bridge rectifier, some chips with no number or number removed...
> Measured some things. 3.3 V regulator OK, seems all OK, must be the sensor.
> Then I spotted the microscopic small text on the back:
> it says : Buy a new one after 5 years
> then in even smaller text
> production date 15 5 2018
> replacement date 15 5 2023
> I looked for a battery backup or if they used a timer.... No.
> I think this is crooked, a new one now is about 29 Euro / dollar:
> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p168047.html
> So when I bought it it was already 1 year old!
>
> So I won't play and will use one of these:
> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
> 3 Euro 50 cents
> 10 times cheaper, will hang it on an ADC channel of some other ethernet connected sensor I build...
> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
> still space for a second sensor.
> Or maybe I will just integrate that into the existing housing of the old one...
> But what a business model?
> Sell a new car every few years if your headlights fail?

What technology do they use? IIRC a lot of gas sensors use some kind hybrid JFET with the gate exposed to the gas.

On a sunny day (Tue, 26 Sep 2023 17:12:28 -0400) it happened ABLE1
<somebody@nowhere.com> wrote in <%OHQM.170527$_Lv6.47565@fx12.iad>:

>On 9/26/2023 12:00 PM, Jan Panteltje wrote:
>> Interesting gas sensor -business-
>>
>> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
>> About 30 USD back then, runs on 12V a wallwart that came with it, and has a VERY LOAD beep if it detects even a slight bit of
>> gas.
>>
>> So yesterday. while working upstairs with the soldering iron on some audio stuff, I heard a load beeeeeeep
>> continuous beep.
>> Thought first it was one of the fire detectors (several in the house),
>> went downstairs and found that gas detector.
>> Did not smell any gas though..
>> Unplugged it, took it outside in the fresh air, powered it, and it beeped again
>> So looks defective...
>>
>> Today I was really curious what was wrong with it, checked the 12 V wallwart, was OK, used scope, no ripple.
>> Opened it up and looked inside at the sensor PCB..
>> 5 or 6 chips, a bridge rectifier, some chips with no number or number removed...
>> Measured some things. 3.3 V regulator OK, seems all OK, must be the sensor.
>> Then I spotted the microscopic small text on the back:
>> it says : Buy a new one after 5 years
>> then in even smaller text
>> production date 15 5 2018
>> replacement date 15 5 2023
>> I looked for a battery backup or if they used a timer.... No.
>> I think this is crooked, a new one now is about 29 Euro / dollar:
>> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p168047.html
>> So when I bought it it was already 1 year old!
>>
>> So I won't play and will use one of these:
>> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
>> 3 Euro 50 cents
>> 10 times cheaper, will hang it on an ADC channel of some other ethernet connected sensor I build...
>> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
>> still space for a second sensor.
>> Or maybe I will just integrate that into the existing housing of the old one...
>> But what a business model?
>> Sell a new car every few years if your headlights fail?
>
>Jan,
>
>Gas Testers or Sniffers have an approximate life span of about 7 years
>depending on manufacture. In the circuitry there is a counter that
>when the programmed max is reached the unit QUITS!! DONE!! EXPIRES!!
>
>YUP time to buy another one!!
>
>Have a better day!!
>
>Les

OK, I figured how they did it I think,
the unmarked chip looks like a PIC micro
Use internal oscillator, drive internal counter, make an x second pulse,
write to 32 bit or more value in EEPROM in the chip,
when 5 years counted switch to self-destruct mode.
Nice piece of electronics made with care (it looks like).
But I do not like the business model,
but advertising with;
'This thing will self-destruct in 5 years'
(to make you buy a new one)
would keep buyers away
I may scope it to see if it really is a PIC maybe later,
long ago I could list those PICs (used to be in TV smart cards)
The self-destruct feature could be used for all sort of things
How about in your cellphone or TV even?
I disagree with that practice, sure for safety in gas detection? Maybe.
User may simply decide not to buy a new detector!!!
So we need some law-enforcement here!!!!

On a sunny day (Tue, 26 Sep 2023 15:05:39 -0700 (PDT)) it happened Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote in
<b8526826-1f25-44c4-84bf-c8c5e14f9239n@googlegroups.com>:

>On Tuesday, September 26, 2023 at 12:00:35 PM UTC-4, Jan Panteltje =
>wrote:
>> Interesting gas sensor -business-
>>
>> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
>> About 30 USD back then, runs on 12V a wallwart that came with it, and has=
> a VERY LOAD beep if it detects even a slight bit of gas.
>>
>> So yesterday. while working upstairs with the soldering iron on some audi=
>o stuff, I heard a load beeeeeeep
>> continuous beep.
>> Thought first it was one of the fire detectors (several in the house),
>> went downstairs and found that gas detector.
>> Did not smell any gas though..
>> Unplugged it, took it outside in the fresh air, powered it, and it beeped=
> again
>> So looks defective...
>>
>> Today I was really curious what was wrong with it, checked the 12 V wallw=
>art, was OK, used scope, no ripple.
>> Opened it up and looked inside at the sensor PCB..
>> 5 or 6 chips, a bridge rectifier, some chips with no number or number rem=
>oved...
>> Measured some things. 3.3 V regulator OK, seems all OK, must be the senso=
>r.
>> Then I spotted the microscopic small text on the back:
>> it says : Buy a new one after 5 years
>> then in even smaller text
>> production date 15 5 2018
>> replacement date 15 5 2023
>> I looked for a battery backup or if they used a timer.... No.
>> I think this is crooked, a new one now is about 29 Euro / dollar:
>> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p16=
>8047.html
>> So when I bought it it was already 1 year old!
>>
>> So I won't play and will use one of these:
>> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module=
>
>> 3 Euro 50 cents
>> 10 times cheaper, will hang it on an ADC channel of some other ethernet c=
>onnected sensor I build...
>> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
>> still space for a second sensor.
>> Or maybe I will just integrate that into the existing housing of the old =
>one...
>> But what a business model?
>> Sell a new car every few years if your headlights fail?
>
>What technology do they use? IIRC a lot of gas sensors use some kind hybrid=
> JFET with the gate exposed to the gas.

See:
https://components101.com/articles/introduction-to-gas-sensors-types-working-and-applications

On a sunny day (Wed, 27 Sep 2023 05:06:01 GMT) it happened Jan Panteltje
<alien@comet.invalid> wrote in <uf0d7q$leql$1@solani.org>:

>>What technology do they use? IIRC a lot of gas sensors use some kind hybrid=
>> JFET with the gate exposed to the gas.
>
>See:
> https://components101.com/articles/introduction-to-gas-sensors-types-working-and-applications

I unsoldered the sensor and got the type model for this thing: NAP-55A
It turned out to have a broken (infinite ohms) heater element.
Supply voltage of 2.5V was OK and rest of the electronics seemed OK.
https://www.nemoto.eu/nap-55-flammable-gas-sensor

Well at lasat the wallwart that came with it can be re-used for something.

About 10 USD on ebay:
https://www.ebay.com/itm/381841452931

But I am going to try the cheaper ones with my own circuit, faster delivery too (local shop).
https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module

On Wed, 27 Sep 2023 04:59:44 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

>On a sunny day (Tue, 26 Sep 2023 17:12:28 -0400) it happened ABLE1
><somebody@nowhere.com> wrote in <%OHQM.170527$_Lv6.47565@fx12.iad>:
>
>>On 9/26/2023 12:00 PM, Jan Panteltje wrote:
>>> Interesting gas sensor -business-
>>>
>>> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
>>> About 30 USD back then, runs on 12V a wallwart that came with it, and has a VERY LOAD beep if it detects even a slight bit of
>>> gas.
>>>
>>> So yesterday. while working upstairs with the soldering iron on some audio stuff, I heard a load beeeeeeep
>>> continuous beep.
>>> Thought first it was one of the fire detectors (several in the house),
>>> went downstairs and found that gas detector.
>>> Did not smell any gas though..
>>> Unplugged it, took it outside in the fresh air, powered it, and it beeped again
>>> So looks defective...
>>>
>>> Today I was really curious what was wrong with it, checked the 12 V wallwart, was OK, used scope, no ripple.
>>> Opened it up and looked inside at the sensor PCB..
>>> 5 or 6 chips, a bridge rectifier, some chips with no number or number removed...
>>> Measured some things. 3.3 V regulator OK, seems all OK, must be the sensor.
>>> Then I spotted the microscopic small text on the back:
>>> it says : Buy a new one after 5 years
>>> then in even smaller text
>>> production date 15 5 2018
>>> replacement date 15 5 2023
>>> I looked for a battery backup or if they used a timer.... No.
>>> I think this is crooked, a new one now is about 29 Euro / dollar:
>>> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p168047.html
>>> So when I bought it it was already 1 year old!
>>>
>>> So I won't play and will use one of these:
>>> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
>>> 3 Euro 50 cents
>>> 10 times cheaper, will hang it on an ADC channel of some other ethernet connected sensor I build...
>>> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
>>> still space for a second sensor.
>>> Or maybe I will just integrate that into the existing housing of the old one...
>>> But what a business model?
>>> Sell a new car every few years if your headlights fail?
>>
>>Jan,
>>
>>Gas Testers or Sniffers have an approximate life span of about 7 years
>>depending on manufacture. In the circuitry there is a counter that
>>when the programmed max is reached the unit QUITS!! DONE!! EXPIRES!!
>>
>>YUP time to buy another one!!
>>
>>Have a better day!!
>>
>>Les
>
>OK, I figured how they did it I think,
>the unmarked chip looks like a PIC micro
>Use internal oscillator, drive internal counter, make an x second pulse,
>write to 32 bit or more value in EEPROM in the chip,
>when 5 years counted switch to self-destruct mode.
>Nice piece of electronics made with care (it looks like).
>But I do not like the business model,
>but advertising with;
> 'This thing will self-destruct in 5 years'
> (to make you buy a new one)
> would keep buyers away
>I may scope it to see if it really is a PIC maybe later,
>long ago I could list those PICs (used to be in TV smart cards)
>The self-destruct feature could be used for all sort of things
>How about in your cellphone or TV even?
>I disagree with that practice, sure for safety in gas detection? Maybe.
>User may simply decide not to buy a new detector!!!
>So we need some law-enforcement here!!!!

No, the sensor itself physically wears out. There is no indication of
wear out, but the sensor element becomes less and less sensitive.

And lithium batteries are good for ten years or so.

So it makes perfect sense to make mass-market safety-related gas
sensors commit suicide after seven years.

Otherwise, they will never be replaced even when totally useless.

Joe Gwinn

On a sunny day (Wed, 27 Sep 2023 17:33:33 -0400) it happened Joe Gwinn
<joegwinn@comcast.net> wrote in <7k79hi13fcmjokjd9vnbh8b76v7nkqrfiq@4ax.com>:

>On Wed, 27 Sep 2023 04:59:44 GMT, Jan Panteltje <alien@comet.invalid>
>wrote:
>
>>On a sunny day (Tue, 26 Sep 2023 17:12:28 -0400) it happened ABLE1
>><somebody@nowhere.com> wrote in <%OHQM.170527$_Lv6.47565@fx12.iad>:
>>
>>>On 9/26/2023 12:00 PM, Jan Panteltje wrote:
>>>> Interesting gas sensor -business-
>>>>
>>>> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
>>>> About 30 USD back then, runs on 12V a wallwart that came with it, and has a VERY LOAD beep if it detects even a slight bit
>>>> of
>>>> gas.
>>>>
>>>> So yesterday. while working upstairs with the soldering iron on some audio stuff, I heard a load beeeeeeep
>>>> continuous beep.
>>>> Thought first it was one of the fire detectors (several in the house),
>>>> went downstairs and found that gas detector.
>>>> Did not smell any gas though..
>>>> Unplugged it, took it outside in the fresh air, powered it, and it beeped again
>>>> So looks defective...
>>>>
>>>> Today I was really curious what was wrong with it, checked the 12 V wallwart, was OK, used scope, no ripple.
>>>> Opened it up and looked inside at the sensor PCB..
>>>> 5 or 6 chips, a bridge rectifier, some chips with no number or number removed...
>>>> Measured some things. 3.3 V regulator OK, seems all OK, must be the sensor.
>>>> Then I spotted the microscopic small text on the back:
>>>> it says : Buy a new one after 5 years
>>>> then in even smaller text
>>>> production date 15 5 2018
>>>> replacement date 15 5 2023
>>>> I looked for a battery backup or if they used a timer.... No.
>>>> I think this is crooked, a new one now is about 29 Euro / dollar:
>>>> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p168047.html
>>>> So when I bought it it was already 1 year old!
>>>>
>>>> So I won't play and will use one of these:
>>>> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
>>>> 3 Euro 50 cents
>>>> 10 times cheaper, will hang it on an ADC channel of some other ethernet connected sensor I build...
>>>> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
>>>> still space for a second sensor.
>>>> Or maybe I will just integrate that into the existing housing of the old one...
>>>> But what a business model?
>>>> Sell a new car every few years if your headlights fail?
>>>
>>>Jan,
>>>
>>>Gas Testers or Sniffers have an approximate life span of about 7 years
>>>depending on manufacture. In the circuitry there is a counter that
>>>when the programmed max is reached the unit QUITS!! DONE!! EXPIRES!!
>>>
>>>YUP time to buy another one!!
>>>
>>>Have a better day!!
>>>
>>>Les
>>
>>OK, I figured how they did it I think,
>>the unmarked chip looks like a PIC micro
>>Use internal oscillator, drive internal counter, make an x second pulse,
>>write to 32 bit or more value in EEPROM in the chip,
>>when 5 years counted switch to self-destruct mode.
>>Nice piece of electronics made with care (it looks like).
>>But I do not like the business model,
>>but advertising with;
>> 'This thing will self-destruct in 5 years'
>> (to make you buy a new one)
>> would keep buyers away
>>I may scope it to see if it really is a PIC maybe later,
>>long ago I could list those PICs (used to be in TV smart cards)
>>The self-destruct feature could be used for all sort of things
>>How about in your cellphone or TV even?
>>I disagree with that practice, sure for safety in gas detection? Maybe.
>>User may simply decide not to buy a new detector!!!
>>So we need some law-enforcement here!!!!
>
>No, the sensor itself physically wears out. There is no indication of
>wear out, but the sensor element becomes less and less sensitive.
>
>And lithium batteries are good for ten years or so.

Sure, but this model is mains powered (via a wallwart), it has a bridge rectifier at the power input
and can that way be used in for example a boat or caravan from a 12V battery,
even if you swap + and - ...

I am still not sure if just the sensor is defective,
have made a circuit diagram from part of the circuit,
lots of electronics in there!
several voltage regulators, opamp, what looks like a PIC? micro
will have an other look later...

>So it makes perfect sense to make mass-market safety-related gas
>sensors commit suicide after seven years.
>
>Otherwise, they will never be replaced even when totally useless.

Well, tell you one thing
Once I installed an alarm system, then we went on holiday to 'merrica I think it was.
When we came back the neighbors told us the alarms had gone off,
and the police came, and somehow got entry to switch it off.
The reason for the alarm was that some installer who fixed the electrical doorbell
had moved the bell temporally next to the alarm box, the sparks of the bell triggered the electronics...
I am glad this thing started beeping when I was home and that it was in the middle of the day.
There must be better ways...
I have added voice messages to my alarm system here, so you do not have beeps but
it may say, 'intruder detected' or something.
All runs 24/7 on UPS with Raspberry Pis that record video too from several cameras, some IR.
So there is a gas sensor input project planned now.
And the alligator feed and trapdoor opening automatically.

This thing was so load you could hear it at the end of the street.

On Wednesday, September 27, 2023 at 1:06:10 AM UTC-4, Jan Panteltje wrote:
> On a sunny day (Tue, 26 Sep 2023 15:05:39 -0700 (PDT)) it happened Fred Bloggs
> <bloggs.fred...@gmail.com> wrote in
> <b8526826-1f25-44c4...@googlegroups.com>:
>
> >On Tuesday, September 26, 2023 at 12:00:35 PM UTC-4, Jan Panteltje > >wrote:
> >> Interesting gas sensor -business-
> >>
> >> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
> >> About 30 USD back then, runs on 12V a wallwart that came with it, and has> > a VERY LOAD beep if it detects even a slight bit of gas.
> >>
> >> So yesterday. while working upstairs with the soldering iron on some audi> >o stuff, I heard a load beeeeeeep
> >> continuous beep.
> >> Thought first it was one of the fire detectors (several in the house),
> >> went downstairs and found that gas detector.
> >> Did not smell any gas though..
> >> Unplugged it, took it outside in the fresh air, powered it, and it beeped=
> > again
> >> So looks defective...
> >>
> >> Today I was really curious what was wrong with it, checked the 12 V wallw> >art, was OK, used scope, no ripple.
> >> Opened it up and looked inside at the sensor PCB..
> >> 5 or 6 chips, a bridge rectifier, some chips with no number or number rem=
> >oved...
> >> Measured some things. 3.3 V regulator OK, seems all OK, must be the senso> >r.
> >> Then I spotted the microscopic small text on the back:
> >> it says : Buy a new one after 5 years
> >> then in even smaller text
> >> production date 15 5 2018
> >> replacement date 15 5 2023
> >> I looked for a battery backup or if they used a timer.... No.
> >> I think this is crooked, a new one now is about 29 Euro / dollar:
> >> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-p16> >8047.html
> >> So when I bought it it was already 1 year old!
> >>
> >> So I won't play and will use one of these:
> >> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module=
> >
> >> 3 Euro 50 cents
> >> 10 times cheaper, will hang it on an ADC channel of some other ethernet c> >onnected sensor I build...
> >> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
> >> still space for a second sensor.
> >> Or maybe I will just integrate that into the existing housing of the old > >one...
> >> But what a business model?
> >> Sell a new car every few years if your headlights fail?
> >
> >What technology do they use? IIRC a lot of gas sensors use some kind hybrid> > JFET with the gate exposed to the gas.
> See:
> https://components101.com/articles/introduction-to-gas-sensors-types-working-and-applications

The way the MOS sensor works is to simply change channel resistance over something like a 10:1 range. So it's part of simple relaxation oscillator interrupting the PIC, or the PIC is detecting a major resistance change some other simple and cheap way. The sensor lifetime is limited by gas exposure. Sometimes, exposure to a high density gas atmosphere will ruin it. In the long term the sensitivity degrades below spec. The detectors are supposed to be changed out every 5 years on average, but they don't mention any of that in their advertizing.

On a sunny day (Thu, 28 Sep 2023 11:56:03 -0700 (PDT)) it happened Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote in
<c79bfa7e-2dfc-43de-bdd1-c50c3a33dc9an@googlegroups.com>:

>On Wednesday, September 27, 2023 at 1:06:10 AM UTC-4, Jan Panteltje=
> wrote:
>> On a sunny day (Tue, 26 Sep 2023 15:05:39 -0700 (PDT)) it happened Fred B=
>loggs
>> <bloggs.fred...@gmail.com> wrote in
>> <b8526826-1f25-44c4...@googlegroups.com>:
>>
>> >On Tuesday, September 26, 2023 at 12:00:35 PM UTC-4, Jan Pantelt=
>je =
>> >wrote:
>> >> Interesting gas sensor -business-
>> >>
>> >> In 2019 I bought a gas sensor, to warn me if cooking gas is leaking.
>> >> About 30 USD back then, runs on 12V a wallwart that came with it, and =
>has=
>> > a VERY LOAD beep if it detects even a slight bit of gas.
>> >>
>> >> So yesterday. while working upstairs with the soldering iron on some a=
>udi=
>> >o stuff, I heard a load beeeeeeep
>> >> continuous beep.
>> >> Thought first it was one of the fire detectors (several in the house),=
>
>> >> went downstairs and found that gas detector.
>> >> Did not smell any gas though..
>> >> Unplugged it, took it outside in the fresh air, powered it, and it bee=
>ped=
>> > again
>> >> So looks defective...
>> >>
>> >> Today I was really curious what was wrong with it, checked the 12 V wa=
>llw=
>> >art, was OK, used scope, no ripple.
>> >> Opened it up and looked inside at the sensor PCB..
>> >> 5 or 6 chips, a bridge rectifier, some chips with no number or number =
>rem=
>> >oved...
>> >> Measured some things. 3.3 V regulator OK, seems all OK, must be the se=
>nso=
>> >r.
>> >> Then I spotted the microscopic small text on the back:
>> >> it says : Buy a new one after 5 years
>> >> then in even smaller text
>> >> production date 15 5 2018
>> >> replacement date 15 5 2023
>> >> I looked for a battery backup or if they used a timer.... No.
>> >> I think this is crooked, a new one now is about 29 Euro / dollar:
>> >> https://www.reichelt.com/de/nl/gasmelder-en-50194-gasalarm-gm-cc-3000-=
>p16=
>> >8047.html
>> >> So when I bought it it was already 1 year old!
>> >>
>> >> So I won't play and will use one of these:
>> >> https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-mod=
>ule=
>> >
>> >> 3 Euro 50 cents
>> >> 10 times cheaper, will hang it on an ADC channel of some other etherne=
>t c=
>> >onnected sensor I build...
>> >> https://panteltje.nl/pub/CO_sensor_POE_UDP_PCB_IMG_6203.JPG
>> >> still space for a second sensor.
>> >> Or maybe I will just integrate that into the existing housing of the o=
>ld =
>> >one...
>> >> But what a business model?
>> >> Sell a new car every few years if your headlights fail?
>> >
>> >What technology do they use? IIRC a lot of gas sensors use some kind hyb=
>rid=
>> > JFET with the gate exposed to the gas.
>> See:
>> https://components101.com/articles/introduction-to-gas-sensors-types-work=
>ing-and-applications
>
>The way the MOS sensor works is to simply change channel resistance over so=
>mething like a 10:1 range. So it's part of simple relaxation oscillator int=
>errupting the PIC, or the PIC is detecting a major resistance change some o=
>ther simple and cheap way. The sensor lifetime is limited by gas exposure. =
>Sometimes, exposure to a high density gas atmosphere will ruin it. In the l=
>ong term the sensitivity degrades below spec. The detectors are supposed to=
> be changed out every 5 years on average, but they don't mention any of tha=
>t in their advertizing.

I have ordered a MQ4 sensor locally,
https://www.tinytronics.nl/shop/en/sensors/air/gas/mq-4-gas-sensor-module
just got email it has been shipped, normal mail, should be here in a few days.
We will see !!