M1 is a MOSFET. R2 is a low value resistor in series with M1 and the Load (here 1Ω) and develops a voltage proportional to the load current (which is common to all three). This voltage is compared, by opamp U1, to an adjustable reference voltage which is tapped off by potentiometer U3 across a 2.5V fixed reference voltage generator U2. The opamp output drives the gate of M1 and so adjusts the load current such that the two voltage inputs to the opamp are equal. Since the reference voltage is constant that means the load-current-derived voltage is also constant. M1 is your gizmo which allows more or less current flow as required to keep the load current constant.

Thanks Alec, that's a very helpful description (although humbly, still a tad over my head). I will certainly keep it for reference! Much appreciated!

Oh yes it will. Unless you **deliberately** limit the current then the load **will** dictate what the current is.

I understand where you're coming from. A voltage source can in theory pass "infinite" current with an infinitely low-R load (right?). I am definitely having some confusion for my application in particular, though.

To elaborate, the I-V relationship for my load is S-shaped. It passes negligible current at low applied voltages, then follows ohm's law in its "operating" zone, before leveling off at a max current irrespective of voltage. I want to operate at the top of the ohm's law region, and therefore must apply the corresponding voltage at this current. Therefore, I design my source ("V2") to do this. Picture V2 as a battery, where the voltage slowly decays as it is discharged. This must be compensated with a supplemental power source.

Perhaps I just answered my own question, and it is actually the voltage I need to maintain? So if that's the case, is there such a circuit element (device) that can maintain constant voltage? And in this case, perhaps I should be connecting these sources in series?

I am sorry that if I am not explaining or interpreting things correctly. I am learning.