The Wheatstone bridge is a ubiquitous circuit configuration that is useful in detecting small changes in resistance.

In his video [Afroman] describes how the LM317 can be used to regulate current rather than voltage to provide a constant current source under ... While this circuit may not be as efficient as ...

Luckily, there’s a fully featured free and open source circuit simulation software called Qucs (Quite Universal Circuit Simulator), released under the GPL, that offers a decent alternative to ...