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How to Measure ROOM CO2 concentration with 20$ sensor "MH-Z19" and Raspberry Pi, 2nd edition.

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MH-Z19 CO2 concentration SensorMH-Z19 is a small, low-cost, weigh 15g CO2 sensor module product by 郑州炜盛电子科技.
You can buy it at an online shop like eBay or aliexpress about 20$.



The electrical interface of this sensor is compatible with Raspberry Pi. So you can make your D.I.Y. CO2 Monitor with MH-Z19, Raspberry Pi.



The normal CO2 concentration is about 400ppm. On a global scale, this value is sensitive to the effect of the activities of the plants, seasonally it gets lower in summer due to vigorous plants photosynthesis and getting higher in winter, and the long-range trend is continuing to rise linearly. The Japanese Meteorological Agency reports CO2 concentration chart continuously as hire. It indicates a clear trend of rising.

On your room-scale, in a closed room with 2 people, CO2 concentration rise up to 1,200ppm soon and keep falling slowly after 1 person go out.


In a high CO2 concentration room as 1200ppm, somebody can get a headache or sleepiness.

But no need to concern about…

Monitoring all over the world with 3G Network for not more than 10$ monthly payment

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The MONITOR™ is a free web service that shows the latest posted picture and sensor data. With 2$ USB Camera and Raspberry Pi, you can get your D.I.Y. Monitoring for an inexpensive cost.

You can get started MONITOR™ for Free here!


Even at the place where no available network access all over the world, your Monitoring system still works well with 3G dongle & International Data SIM card.

I write from now on how to set up an inexpensive 3G network environment on your RaspberryPi easily. USB 3G dongle and Data SIM card utilities "gc_modem" In General, a setting of USB 3G dongle and SIM Card is troublesome works with bizarre technical terms, like udev rule, apn, and so on.
The "gc_modem" is useful utilities to change there troublesome works mentioned above to just select the name of dongle and SIM card which you'll use. 
gc_modem is consist of the following parts: udev_rules : Definitions of each USB 3G dongles which will be mentioned.wvdial : Definitions of each…

How to get Time Series Chart of the room Temperature, Relative Humidity and Humidity Deficit with 3$ sensor "DHT22" and Raspberry Pi without any electronic works nor any programming.

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DHT22 (AM2302) temperature & humidity Sensor Though DHT22 (another name AM2302) sensor is small and low-cost, but have a decent quality of precision of measuring temp/humidity.
You can buy the ready to use breakout of DHT22 for 3 - 4$ from eBay.


Why measure the room humidity as well as temperature Not only to get comfortable air but also to measure and control humidity has a lot of purposes, for example:
- In high humidity rooms like summer or monsoon season in Japan, where I live in, It often grows the mold everywhere on the wall, clothes, food and so on. The mod can't be active under low relative humidity. I'm controlling my room to keep relative humidity under 60% to block to grows the mold. The filamentous fungi, which is many of the causes of plant disease, is in the same family of mold, so a lot of plant disease also can avoid by humidity control. 
- Some plant is known that they close there pore under hight Humidity Deficit (I'll explain this later) to block loo…

How to make Human Detection Security camera with under 1$ Human Detection Senser, 2$ USB Webam & Raspberry Pi

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With under 1$ Human Detection Sensor,HC-SR501




With 2$ USB Webcam,



and Raspberry Pi connected to the Internet,



You can make Web Base Security Camera System as follows:


PIR Sensor There are many types of Human Detection Sensor, some of these watching infrared light rays and cache shutting out of this, or some these using Millimeter-wave radar. PIR(Passive Infrared Ray) Sensor is one of these Human Detection Sensor which watches the change of thermal infrared emitted from hot objects like Humans, Birds, and Mammals.
The sensor consists of a lens for thermal infrared (white plastic tip in the picture below) and a detector device.
Both parts are inexpensive parts and a detector is low current consumption parts. So, the advantage to use the PIR sensor for Human Detection is:
- Inexpensive - Low current consumption How to setup Step 1. Get account of MONITOR™ and your view_id
On your Web browser, Sign up to MONITOR™, then you can see the following display.


Keep the "view_id" shown …

How to make Security camera with 2$ USB Webam & Beagle Bone Green

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With 2$ USB Webcam,


and Beagle Bone Green connected to the Internet,




You can make Web Base Security Camera System as follows:


According to the BeagleBone Green System Reference Manual section 5.7 USB1 Host Port, the BBG's USB port can provide up to 500mA of current at 5V. It's enough power of the current to share USB WebCam and USB WiFi dongle by USB Hub
For your reference, the following are parts list which I'm using. High-Speed 4-Port USB 3.0 Multi HUB Splitter
price about 4$ from eBay HOT 150Mbps 150M Mini USB WiFi Wireless Adapter
price about 2$ from eBay Mini Stylish USB 2.0 5M Meter Retractable Clip WebCam Web Camera
price about 3$ from eBay The following steps are completely the same as How to make a Security camera with 2$ USB Webcam & Beagle Bone Green. Step 1. Get account of MONITOR™ and your view_id
On your Web browser, Sign up to MONITOR™, then you can see the following display.


Keep the "view_id" shown in the display, you are setting your Raspberry …