How “Hall effect” sensors work

Burglar alarm has them. Car fuel level detectors have them. Even DC current transformers have them. What are we talking about? Hall effect sensors! Whats that, you’ve never heard of them? Well they are a part of your life and all over the place. If you need the electronics in your project to know the position of some mechanical part, odds are that you need to use the Hall effect! But how does it work? Thanx to our favorite science journalist Brady Haran and one of his many channels, Sixty Symbols, we get our answer! In this video, Professor Roger Bowley from The University of Nottingham walk us through the inner working of a hall effect sensor. Named after its discoverer, Edwin Hall, the hall effect has become a very useful phenomenon in modern society, and anyone that build electronics should definitely watch this video!

Start a fire with….a hammer?

Even though we definitively don’t want to encourage smoking, we found this short video from nyblacksmith to have such a high educational value that we couldn’t resist adding it to our collection. By hammering a cold piece of steel over and over in rapid succession, the friction energy from the hammer heats up the piece so much, it can lit a cigarette. This is an excellent demonstration of how hot things can get from friction, and therefore how important it is to avoid friction in mechanical devices. But again, we do not want anyone to smoke! This video may be very clever, but smoking is really stupid.

Welding with friction

Most of us have a general idea of what it takes to weld two pieces of metals together. This general idea usually incorporates an electric current or flame to heat up and melt the metal. But there is another method that is especially suited for welding round parts together, called “Inertia welding” or “Friction welding”. The basic idea is to rub the parts together so fast that friction heat it up to its melting point. In this video from Doug W a specialized machine for inertia welding is used, but any metal lathe with enough torque should do as well. Just make sure you punch the break when the melted metal is squeezed out, in order to get the strongest weld.