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Author Topic: Gas sensors to 1-wire  (Read 12504 times)

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Offline periklast

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Gas sensors to 1-wire
« on: June 08, 2011, 10:58:48 AM »
I have a 1-wire interface and created a snow-depth sensor.
Now, I want to start a new project: measure ozon and air quality (http://www.thaieasyelec.net/index.php/Sensors/GAS/Ozone-O3-Gas-Sensor-MQ-131/p_154.html & http://www.thaieasyelec.net/index.php/Sensors/GAS/Air-Quality-Control-Gas-Sensor-MQ-135/p_155.html ).

Is there or can someone draw a simple scheme for connecting the sensor to 1-wire (probably with the smart-battery-monitor
DS2438 )?

Offline G.O.B.B

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Re: Gas sensors to 1-wire
« Reply #1 on: June 09, 2011, 09:43:58 PM »
You got my attention, cannot help you with the schema, but would like to see the end result :-).

H.

Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #2 on: September 12, 2011, 02:46:05 PM »
I have a 1-wire interface and created a snow-depth sensor.
Now, I want to start a new project: measure ozon and air quality (http://www.thaieasyelec.net/index.php/Sensors/GAS/Ozone-O3-Gas-Sensor-MQ-131/p_154.html & http://www.thaieasyelec.net/index.php/Sensors/GAS/Air-Quality-Control-Gas-Sensor-MQ-135/p_155.html ).

Is there or can someone draw a simple scheme for connecting the sensor to 1-wire (probably with the smart-battery-monitor
DS2438 )?

This is good idea.
You can use this board: http://www.hobby-boards.com/catalog/product_info.php?cPath=22&products_id=91
There is also schema for ds2438 from this device: http://www.hobby-boards.com/catalog/links/ts3-r1/Humidity-Temp-Solar%20v3.2%20Schematic.pdf

Radek
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Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #3 on: September 13, 2011, 08:00:06 PM »
I did a little research.
MQ-135 Sensor detect air particles from 10ppm to 300ppm (1000ppm benzene). 10ppm is high value - I think it is more applicable to alarms.
So we need more sensitive sensor.
TSG 2602 works from 1 to 10ppm - it is much better.
It seems that these sensors are more suitable for measuring indoor air quality. In datasheets don't see information about sensitivity to S0x, NOx, C0x ...etc, despite I think that because of their general sensitivity, will work in outdoor environment.  
I created wiring diagram (see attachment, but circuit is untested) and formula for temperature compensation - these gas sensors is sensitive to temperature and slightly to humidity.

Schema is taken from hobby-boards Temperature/Sun sensor. I do not know whether I chose the optimal resistor values, but trimmer solves everything.  :D

Compensation formula (only for TSG2602):
Code: [Select]
Vcomp = Vin*(-0,028*T+1,6)Where:
"Vin" is meausred voltage
"T" is Temperature in Celsius deg

Then for implemenation to SW is also needed know voltage for clear air (0,9~xV - depends on trimmer position) and voltage for contamined air (0.11V~xV depends on trimmer) - it will be simply readed from OneWireViewer.

Probably in the near future I'll try to order parts and test it. :)

EDIT: Added URLs, fixed bad ppm values (oh my memory... :))

EDIT2: Schema is moved to: http://www.weather-watch.com/smf/index.php/topic,51432.msg425114.html#msg425114
« Last Edit: September 18, 2011, 10:54:48 AM by RAD-X »
Radek
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Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #4 on: September 14, 2011, 04:15:39 AM »
found a     
MQ131 ozone gas detection sensor output analog/TTL
I don't think that the amount of Ozone refers to the overall air quality. Respectively for high value of ground ozone must be present hydrocarbons and/or nitrogen oxides (both present eq. in exhausts) and must be high solar radiation/activity. I think that Carbon Dioxide sensor will be closer to overall air quality.
Nevertheless, these sensors have low sensitivity - at least I think - It starts from 10ppm. See datasheet for MQ 131 or MQ 135 and others similar.

I found great gas sensor test at http://www.staceyk.org/airSensors/sensoroutput.php

BTW: MQ-135 is also on e-bay http://www.ebay.co.uk/itm/MQ135-sensor-Air-quality-sensor-Hazardous-gas-detection-/180713997925?pt=LH_DefaultDomain_0&hash=item2a1364c665
« Last Edit: September 14, 2011, 04:25:03 AM by RAD-X »
Radek
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Offline G.O.B.B

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Re: Gas sensors to 1-wire
« Reply #5 on: September 14, 2011, 08:57:08 PM »
Wow, nice guys,

I am very interested in this, would it be possible to get a "turn key"  solution and use WD to log the data?




H.

Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #6 on: September 16, 2011, 05:32:49 PM »
TSG 2602 arrived yesterday (bought at rs-online.com).
Works very well. Detects cigarette smoke, some fumes, VOCs etc..  :hello1:
I modified the scheme for maximal sensitivity. See attachment.
The output voltage depends on the quality of air and is between approx 0,4 - 4,7V.

Now we need support for Air Quality sensor in WD.
If possible:
- field for AQ ROM at 1-Wire reader in "Main setup" tab
- Checkbox for AQ sensor temperature compensation - on these measured values will be applied temperature compensation for TSG2602: Vout = Vin*(-0,028*T+1,6) where: "Vin" is meausred voltage and "T" is Temperature in Celsius deg. Or this checkbox may be replaced with field where will be added equation for specific sensor.
- Output can be Air Quality index (check box in 1-wire reader):
    - configuration at 1-Wire reader in "Other settings" tab where will be fields for minimal and maximal voltage.
    - Air Quality Index = (Vmax-Vmin)/500*(Vmax-Vact) where "Vact" is actual measured value.
- New column "1_wire_Air_Quality" for WDMySQL  
- WD Graphs for AQ
- WD Main window may include AQI number and status word.

And then we have another weather value that can be measured and used in WD.  8)

What do you think?
« Last Edit: September 18, 2011, 10:54:23 AM by RAD-X »
Radek
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Offline G.O.B.B

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Re: Gas sensors to 1-wire
« Reply #7 on: September 16, 2011, 05:34:13 PM »
Turn Key, is the same as plug and play.

Whole kid assembled, you simply plug it in and configure WD to use it.

H.

Offline G.O.B.B

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Re: Gas sensors to 1-wire
« Reply #8 on: September 16, 2011, 05:37:08 PM »

What do you think?

I think it is brilliant :-).

H.

Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #9 on: September 16, 2011, 06:34:04 PM »
I already got a GP2Y 1010AU0F  dust sensor

With this sensor can be measured a Particulate Matter (PM10 or even smaller particles). But reading data from this sensor isn't easy (10ms pulses). How did you solved it? Do you have a schematic?
« Last Edit: September 16, 2011, 09:35:27 PM by RAD-X »
Radek
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Offline eongibier

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Re: Gas sensors to 1-wire
« Reply #10 on: September 17, 2011, 09:37:34 AM »
Hello,

(Sorry for English, it is about a translator)

I am interested by this project, WD is you it compatible?
Thank you.
Serge

Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #11 on: September 17, 2011, 09:57:25 AM »
Hello,

(Sorry for English, it is about a translator)

I am interested by this project, WD is you it compatible?
Thank you.
Serge

Currently WD not able to reasonably use the data from this sensor.
But I can to try ask Brian if he would do something with it.
Radek
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Offline eongibier

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Re: Gas sensors to 1-wire
« Reply #12 on: September 17, 2011, 10:11:41 AM »
Ok Merci Rad-X

Offline RAD-X

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Re: Gas sensors to 1-wire
« Reply #13 on: September 17, 2011, 07:59:14 PM »
I have done some deeper research. It seems that TSG2600 is for air quality measuring slightly better than TSG2602 - higher sensitivity for standard city outdoor air contaminants.
See basic classification at http://www.directindustry.com/prod/figaro-engineering/semiconductor-air-quality-sensors-29357-147448.html
info and links at http://lekernel.net/blog/2009/07/toxic-gas-sensors-at-tmplab/
Especially measuring results at http://lekernel.net/blog/2009/09/sanobot-data-for-the-first-half-of-september/
But TSG2602 detect VOCs - eg. leaks of dangerous gases from factory...

I ordered TSG2600 and MQ-135.
Once the parts arrive, I'll try to compare them.

However, some donation for development would be nice. These sensors are not the cheapest.
« Last Edit: September 17, 2011, 08:05:09 PM by RAD-X »
Radek
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Offline eongibier

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Re: Gas sensors to 1-wire
« Reply #14 on: September 18, 2011, 09:51:37 AM »
Hello,
Simply it would be interesting initially if Brian will integrate the probe in WD. Do you have answers?

Thank you
Serge