The Shinyei++ analog experiment
Using direct analog readings instead of the LPO

Share: aqicn.org/sensor/shinyei-plusplus/
For a complete list of all the Air Quality Sensors test on the World Air Quality Index project, check our sensor overview page.

Introduction

This experiment is based on a modified Shinyei sensor, where the analog readings is taken before the schmidt trigger which converts the analog signal into the 0/1 LPO.

From the schematics below[1], the idea is to take the raw ouput of the diode directly after the first filter (TP6). However, since the frequency is still very high at TP6, which would require an high CPU DAC running at several hundreds of Mzh, we we getting the analog data from TP4.

Note that TP7 is just used for refence and hardware debugging, and not used in this experiment.

Raw analog readings

Regular LPO readings


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[1] Taken from Tracy Allen's reverse engineering work: http://takingspace.org/wp-content/uploads/ShinyeiPPD42NS_Deconstruction_TracyAllen.pdf

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About the Air Quality Levels

AQI Air Pollution Level Health Implications Cautionary Statement (for PM2.5)
0 - 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk None
51 -100 Moderate Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution. Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
101-150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected. Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
151-200 Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion
201-300 Very Unhealthy Health warnings of emergency conditions. The entire population is more likely to be affected. Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.
300+ Hazardous Health alert: everyone may experience more serious health effects Everyone should avoid all outdoor exertion

To know more about Air Quality and Pollution, check the wikipedia Air Quality topic or the airnow guide to Air Quality and Your Health.

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