ESP8266 Temperature and Humidity Web Service

Skraćena veza:

After I successfuly tested HTTP server using Arduino and Ethernet Shield, I decided to try to accomplish the same thing using wireless connectivity. I decided to use ESP8266 on NodeMCU board. That is microcontroler with wireless interface all in one package, and quite low priced which makes it interesting for various purposes. I used the same temperature and humidity sensor DHT-22.

ESP8266 is supported within Arduino IDE which is big plus, as one can use the same development environment.

Soon I realized that popularity of this platform is well earned. It was very easy to set it up. […]
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Arduino Temperature and Humidity Web Service

Skraćena veza:

I needed simple device that is able to measure temperature and make it available for collecting that info from remote places via Internet. Arduino platform was the first thought and it ended up as expected: nice and simple.

For hardware I used Arduino UNO, Ethernet Shield and DHT22 Temperature and Humidity sensor.

Ethernet Shield pinpoint matches Arduino UNO so it is simply attached on top of it. It provides RJ45 connector for ethernet connection and SD card socket which I did not need for this small project.

All pins on Ethernet Shield are pass-through which means all Arduino pins are available on the this shield too. […]
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Iron Powder Toroid Cores Color Codes

Skraćena veza:

Iron Powder Toroid Cores part numbers are presented using format Tddd-m where dd is core diameter in tenths of inch and m is material grade. Also, cores are color coded to represent material grade.

Material grade defines frequency range core may be used for. There is no strict standard for coding but for informal purpose this table can be used.

Color Frequency
0 Tan/Tan 50 MHz – 350 MHz
1 Blue/Clear 150 kHz – 3 MHz
2 Red/Clear 250 kHz – 10 Mhz
3 Gray/Clear 20 kHz – 1 MHz
4 Blue/White 3 MHz – 40 MHz
6 Yellow /Clear 3 MHz – 40 MHz
7 White/Clear 1 MHz – 25 MHz
8 Orange/Clear 20 kHz – 1 MHz
10 Black/Clear 15 MHz – 100 MHz
12 Green/White 30 MHz – 250 MHz
15 Red/White 150 kHz – 3 MHz
17 Blue/Yellow 20 MHz – 200 MHz
42 Blue/Red 30 kHz – 80 kHz


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