Arduino is a very interesting device through which we can build a lot of unusual electronic designs. The cost of original device such as Arduino Uno is about 25$ and even if we decide to buy Chinese substitute rarely wewi;; be able to find anything with price lower than 5$. For many projects this may be already suitable price, but with all the options offered by Arduino Uno we usually only need what gives us a main component which is microcontroller and it’s price and size is not large.
