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### Topic: Finding the approximation equation for MAX30105 (Read 365 times)previous topic - next topic

#### chandantaluja

##### Nov 12, 2018, 05:37 am
I am working on MAX30105 sensor, and i have got the curve of sensor voltage v/s smoke ppm as output of this sensor.

Kindly help me to plot appropriate equation for this curve.

I have attached the curve.

#### el_supremo

#1
##### Nov 12, 2018, 04:52 pm
That doesn't look like it's a valid curve. A smoke density of 3ppm can be indicated by six different voltages.
Where did you get that curve from?

Pete
Don't send me technical questions via Private Message.

#### jremington

#2
##### Nov 12, 2018, 05:03 pmLast Edit: Nov 12, 2018, 05:04 pm by jremington
Those data are so noisy that it will be impossible to fit any useful curve.

How did you determine the "smoke value in PPM" for each data point?

For a tutorial on device calibration, see https://learn.adafruit.com/calibrating-sensors/why-calibrate

#### chandantaluja

#3
##### Nov 13, 2018, 12:07 pm
That doesn't look like it's a valid curve. A smoke density of 3ppm can be indicated by six different voltages.
Where did you get that curve from?

Pete
I ran max30105 and MQ-2 simultaneously. the three outputs of max30105 and the smoke output of MQ-2 was observed. After this I averaged the values I received appropiately to derive this.

Each output from the LED of the MAX30105 was converted into a voltage and the values were plotted then.

#### jremington

#4
##### Nov 13, 2018, 02:30 pm
Why do you think the MQ-2 data mean anything?

#### chandantaluja

#5
##### Nov 15, 2018, 07:47 am
because i needed something for reference and i couldn't find any other smoke sensor

#### jremington

#6
##### Nov 15, 2018, 03:23 pmLast Edit: Nov 15, 2018, 03:27 pm by jremington
It is not that simple.

First, the MQ-2 is not a smoke sensor, it is a gas sensor that works mainly for detecting H2, LPG, CH4, CO and alcohol. It needs to be "burned in" and calibrated properly to measure anything.

The MAX30105 is also not a smoke sensor. It measures backscattering of light from particles in the air, and the quantity measured does not have a simple relationship to whatever you think the "PPM of smoke" might be.

#### chandantaluja

#7
##### Nov 16, 2018, 08:20 am
It is not that simple.

First, the MQ-2 is not a smoke sensor, it is a gas sensor that works mainly for detecting H2, LPG, CH4, CO and alcohol. It needs to be "burned in" and calibrated properly to measure anything.

The MAX30105 is also not a smoke sensor. It measures backscattering of light from particles in the air, and the quantity measured does not have a simple relationship to whatever you think the "PPM of smoke" might be.