Sometimes it is necessary to choose the electric motor of several fastest or the slowest, or just find out the rpm. I offer the easiest and sufficiently accurate way.
Recently I found in the Internet at a very cheap solution for etching circuit boards. To make it you need components which total cost not more than $0.5.
I'm going to present you an interesting led flashlight that works on Faraday's law of electromagnetic induction. Just shake it - and it will recharge.
What can I say, I made a tiny radio transmitter to spy on somebody, I want to share the experience. It works perfectly
Many of us are still have the old cassette tape record players that already has become useless. You do not even know that such a cassette recorder could be connected to a common mp3 player!
