I have been frustrated for months working through an introductory circuits book, as I want to build many of the circuits, but many of them include constant current sources. Why is it so easy to find voltage sources at your local store (i.e., batteries!), but searching for current sources on the web leads to a complicated bunch of circuit diagrams?
Here is my naive question: using thevenin-norton equivalent circuits, couldn't I transform a battery (i.e., voltage source) into the desired equivalent current source using Vth=InorReq. That is, can I put a voltage source in series with a resistor (as opposed to its equivalent, a current source in parallel with the same resistor)? What is the problem with doing that?
Does anyone know where I could buy a cheap but reliable current source? Why is this so hard?