Many people interested in electronics wonder where to start, but it's likely they mean not so much the theoretical, but rather what to adopt as an initial project. It doesn't have to be anything complex or extravagant. In fact, those early projects also have the potential to attract the little ones at home, and that's how we discover this water mill built from disposable plates and water bottles, which provides enough energy to restore a smartphone's battery, or light up a group of LED lights.
I've received multiple electric shocks and burns from the soldering iron, screamed in frustration when a circuit didn't work, and watched several power supplies end up in orbit, but I'm not trying to fool anyone here: that's my clumsiness in action, part of my (extraordinarily long) learning process. The amount of information available on the Web is gigantic, and the basic concepts needed to start experimenting aren't that complex, yet it's in practice where we find burnt fingers and smoking components. Small steps, simple projects, several versions of the same experiment... all of that adds to our general knowledge. Looking for some inspiration? If the answer is yes, how about a water mill?
Yes, a water mill. One of the oldest and most effective methods to obtain energy, but what this experiment lets us do is not cut wood or process grain, but recharge a smartphone. In one of the latest videos posted by Thomas Kim, who has 60 million views, we see a water mill made from plastic bottles and disposable plates, connected to a small three-phase motor. A simple rectifier circuit, a capacitor, and what appears to be a voltage regulator (I'll assume a 7805) provide the five volts with the necessary amperage for his iPhone to charge. In the second half of the experiment he manages to light up a group of LED lights, and the voltage is about ten volts.
Unfortunately, the video doesn't have deeper instructions, but it's worth noting that it's not obligatory to follow it to the letter. The motor doesn't have to be three-phase, and honestly, the water mill can be replaced with anything else. In the same channel we find another smartphone charger (the second video) where he uses a bicycle (there you can see more closely the circuit design to make it compatible with the iPhone). The best part is that most of the components are recycled or extracted from other devices, like printers and scanners. The weekend is coming, don't forget to try it!
