tag:blogger.com,1999:blog-6100511197805579796.post1990431478394020657..comments2017-07-25T20:59:11.859+02:00Comments on Davide Gironi: MQ gas sensor correlation function estimation by datasheetDavide Gironihttps://plus.google.com/101298883242997956136noreply@blogger.comBlogger42125tag:blogger.com,1999:blog-6100511197805579796.post-28874595371269500372017-07-25T20:59:11.859+02:002017-07-25T20:59:11.859+02:00Hello, at first connect you sensor and measure the...Hello, at first connect you sensor and measure the resistance of the sensor using a multimeter. Then check that your resistance value measured on your micro is almost the same. You should get a resistance value on range, if not it could be your sensor. A valid resistance should be something around 30K.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-69894803281722836512017-07-24T19:33:19.516+02:002017-07-24T19:33:19.516+02:00Dear David,
I was trying to reproduce your projec...Dear David,<br /><br />I was trying to reproduce your project for measuring CO2. I followed the same process you explain on the video, i've got the following values:<br />rO = 42842; a = 111.336; b = -2.716215;<br />which are sufficiently close to those you're reporting.<br />The problem is that i am obtaining Rs/Ro values around 7 and they continue incresing (now they are around 20) thus going further from the maxRsRo = 2.428. Of course the result is an "out of range" message.<br /><br />However, i also performed the same process using the values of r0, a and b that you are using.<br /><br />What are the chances that I am doing wrong?<br /><br />Thank you in advance for your help.Jonathan Luna Arcoshttps://www.blogger.com/profile/17319621640552840063noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-66242399547534889062017-07-19T20:48:46.019+02:002017-07-19T20:48:46.019+02:00Hello, that is the ADC raw value to resistance val...Hello, that is the ADC raw value to resistance value conversion formula for a 10bit adc. Take a look here: https://learn.adafruit.com/thermistor/using-a-thermistor it may help.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-40435783962613129132017-07-18T22:18:46.253+02:002017-07-18T22:18:46.253+02:00Hi Davide, I am working with ozone sensor and i co...Hi Davide, I am working with ozone sensor and i could not understand how "long rS = ((1024.0 * mqR) / adcRaw) - mqR;" came in the formula. I am using the same formula as in your blog, just changing the values and I am not sure if it is correct because it does not match with the photometric ozone analyser that we have in our university. I was wondering if you can explain "long rS = ((1024.0 * mqR) / adcRaw) - mqR;" line in the formula.Nature Bajhttps://www.blogger.com/profile/08033204296211321476noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-34822218683199171522017-07-13T23:56:52.365+02:002017-07-13T23:56:52.365+02:00Hello, power up the sensor header (one Hpin to GND...Hello, power up the sensor header (one Hpin to GND, the other to VCC), then read with a multimeter the value between A and B pin. Start with a multimeter and a spreadsheet, then you can go through a microcontroller.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-80675186484714166092017-07-13T23:54:04.416+02:002017-07-13T23:54:04.416+02:00Hello, it depends on what you mean with sufficient...Hello, it depends on what you mean with sufficient. Also it depends on the gas you are trying to measure. Let's say you get a relistic idea of what it could be the gas amount in ppm :)Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-16889524618161131092017-07-13T21:37:01.635+02:002017-07-13T21:37:01.635+02:00Hi Davide,
Do we measure the resistance between &q...Hi Davide,<br />Do we measure the resistance between "ground pin" and "analog pin" in the sensor to get "mres" if we know the value of ozone ppm?Nature Bajhttps://www.blogger.com/profile/08033204296211321476noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-82568645367629656962017-07-13T15:46:19.840+02:002017-07-13T15:46:19.840+02:00If We use the values obtained from graph provided ...If We use the values obtained from graph provided with datasheet with the help of WebPlotDigitilizer, Will it not be sufficient to get ppm value with marginal accuracy?Waqashttps://www.blogger.com/profile/17407987820926188086noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-51790445621771618802017-07-12T20:20:56.575+02:002017-07-12T20:20:56.575+02:00Hello, you have to measure the resistance of the s...Hello, you have to measure the resistance of the sensor between A and B pin when it's in a know amount of gas. In my example it was in 392ppm of CO2, and i measure 26954ohm. You have to put your sensor in a know amount of methane and measure the resistance of it, please be carefull with CH4.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-5794208320716735332017-07-12T11:05:05.671+02:002017-07-12T11:05:05.671+02:00Hi Davide,
I am working with MQ-4 sensor. In your...Hi Davide,<br /><br />I am working with MQ-4 sensor. In your video at 3:08, you mentioned a value of 26954 ohm at 392 ppm. Where did you get that value?<br /><br />How can I get this value for MQ-4 sensor to calculate methane in ppm. You help would be highly appreciated.Waqashttps://www.blogger.com/profile/17407987820926188086noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-50659245000888975012017-07-07T09:16:16.789+02:002017-07-07T09:16:16.789+02:00Hello, yes you can apply all the proposed steps, b...Hello, yes you can apply all the proposed steps, but for calibration you have to know the O3 ppm and of course the resistance of the sensor.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-73118628613469951162017-07-06T20:44:41.101+02:002017-07-06T20:44:41.101+02:00Hi,
I am having hard time for converting analog da...Hi,<br />I am having hard time for converting analog data from Aurdino sensor to ppm. I am using MQ131 ozone sensor. Can I apply same steps shown in this blog for MQ 131 sensor?Nature Bajhttps://www.blogger.com/profile/08033204296211321476noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-91021987564670493872017-07-06T20:44:19.989+02:002017-07-06T20:44:19.989+02:00This comment has been removed by the author.Nature Bajhttps://www.blogger.com/profile/08033204296211321476noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-51624627203823232722017-06-21T10:00:21.876+02:002017-06-21T10:00:21.876+02:00Hi pedro, thanks for your response Have you ever d...Hi pedro, thanks for your response Have you ever designed a tool using the MQ-7 sensor? Can you help me to complete my task? and Can you give me your email? Or you can chat with me at sinagabonor2320@gmail.com. Sorry if my language is still wrong<br />Sinaga Bonorhttps://www.blogger.com/profile/16391120842133121150noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-82227820195740412302017-06-20T20:42:55.164+02:002017-06-20T20:42:55.164+02:00Hello Pedro. Thank you for your feedback and thank...Hello Pedro. Thank you for your feedback and thank you for sharing your results here. Congratulations for your thesis.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-43463865395894799812017-06-20T10:57:23.960+02:002017-06-20T10:57:23.960+02:00and complementary from the post on the arduino for...and complementary from the post on the arduino forum I mentioned above:<br /><br />Rs = RL * (VCC / VRL - 1)<br /><br />ppmCO = 100 * (RL/Ro * (VCC/VRL - 1))^-1.53Pedro Scaffhttps://www.blogger.com/profile/02300821204114258785noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-83222530656934789912017-06-20T10:45:43.685+02:002017-06-20T10:45:43.685+02:00This comment has been removed by the author.Pedro Scaffhttps://www.blogger.com/profile/02300821204114258785noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-6881009049220665162017-06-20T10:43:11.044+02:002017-06-20T10:43:11.044+02:00Hi Sinaga, hi Davide,
I just worked through the M...Hi Sinaga, hi Davide,<br /><br />I just worked through the MQ-7 and I got the values for MQ-7 CO (not the heater/RL values, I used a module that already does this part). I didn't do a power regression since there were two points that were exactly marked on the data sheet. Here is the octave/matlab code and the final equation:<br /><br />% Inverting x and y axis, points on data sheet: `p0 = (0.09, 4000)` `p1 = (1, 100)`<br />% the x axis represents the ratio Rs/R0<br />% the y axis represents the ppm CO concentration<br />% https://en.wikipedia.org/wiki/Log%E2%80%93log_plot<br />% a straight line on a log-log plot can be represented as a power function<br />% where the slope m = log(y1,y0)/log(x1/x0)<br />% and the equation for Y = a * (x^m)<br />% for the point (1,100) we have a = 100<br />% octave code for the slope m<br />x = [0.09, 4000]<br />y = [1, 100]<br />m = log(y(2),y(1))/log(x(2)/x(1))<br />% our final equation for CO ppm concentration is<br />% ppm = 100 * (Rs/R0)^-1.53<br />% from data sheet: Rs/Ro = (Vcc - VRL) / VRL <br /><br />Thanks for this post, Davide, it has been very helpful for my bachelor thesis :). I also used this post as a helper, and I guess I corrected the value he found there a little bit ;): http://forum.arduino.cc/index.php?topic=294085.0Pedro Scaffhttps://www.blogger.com/profile/02300821204114258785noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-20413771054557958372017-06-19T20:13:50.669+02:002017-06-19T20:13:50.669+02:00Hello, at first you have to check it out the facto...Hello, at first you have to check it out the factor you have found by simply reading the resistence of the sensor with a multimeter and applying the conversion formula with the factor values found. For CO and MQ-7 of course you can not use the a,b Ro value that I provide as sample, but you have to find your how using the method of this blog post.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-81855254900739261562017-06-19T13:52:45.937+02:002017-06-19T13:52:45.937+02:00Sir, why after I follow the above steps, but does ...Sir, why after I follow the above steps, but does not appear the ppm value in view?Sinaga Bonorhttps://www.blogger.com/profile/16391120842133121150noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-58972353789225811102017-06-19T05:37:48.178+02:002017-06-19T05:37:48.178+02:00Before I apologize if my language is still wrong, ...Before I apologize if my language is still wrong, I want to introduce myself first, I am chan heldo, I come from Indonesia. I have the final task to make a CO gas detector using MQ-7 sensor. But I am still confused in making arduino program code for the MQ-7 sensor. I hope you can help me in making the program code. thank youSinaga Bonorhttps://www.blogger.com/profile/16391120842133121150noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-756253131360104732017-06-18T15:55:33.268+02:002017-06-18T15:55:33.268+02:00Hello, yes. The MQ-7 follow the same principles of...Hello, yes. The MQ-7 follow the same principles of this sensor. You have just to built up the conversion points, and the compute factors for the sensor you are using and the gas you would like to trace.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-48136803015390570722017-06-18T15:13:17.405+02:002017-06-18T15:13:17.405+02:00Hello sir, I want to ask, is the program code can ...Hello sir, I want to ask, is the program code can be used for sensor MQ-7? <br />Sinaga Bonorhttps://www.blogger.com/profile/16391120842133121150noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-7465720408805255682017-06-16T15:58:46.913+02:002017-06-16T15:58:46.913+02:00Hello and thank you. You can use the sketch provid...Hello and thank you. You can use the sketch provided in this post as a starting point.Davide Gironihttps://www.blogger.com/profile/16366076989473118278noreply@blogger.comtag:blogger.com,1999:blog-6100511197805579796.post-31477704851797651422017-06-16T13:52:14.708+02:002017-06-16T13:52:14.708+02:00Hi, first of all thanks for this nice article!
I ...Hi, first of all thanks for this nice article!<br /><br />I bought the following mq135 module: http://www.ebay.de/itm/MQ-135-MQ135-Air-Quality-Sensor-Hazardous-Gas-Detection-Module-For-Arduino-AVR-/172115034015? <br /><br />I (kind of ;) ) understood all the calculations but I am not sure how to set up the values from the module.<br /><br />Can you give me any help?<br /><br />Thanks,<br />Pedro Scaff.Pedro Scaffhttps://www.blogger.com/profile/02300821204114258785noreply@blogger.com