When we need some voltage that is different from (less than) the power supply, the humble voltage divider from Ohm's times is the simplest solution. Thus the combination of the supply voltage source and the voltage divider acts as a new artificial voltage source.

This simple solution will be perfect, if we provide perfect load conditions - infinite resistance, open circuit (an interesting phenomenon - imperfect devices become perfect, if only we provide perfect load conditions for them:) But if we connect any (low resistive) load to its output, it will affect the produced voltage and this voltage source becomes imperfect (another interesting phenomenon is that if we keep up the load constant, the imperfect voltage source will become perfect again).

So there is a problem only if the load varies... and it is interesting to see how this imperfect voltage divider source can be converted into a perfect voltage source. Here are my observations.

* First, we can make the lower resistor dynamic, i.e. to replace it with a constant-voltage non-linear resistor (Zener diode, varistor, etc.)

* Second, we can make one of (or both) the resistors variable and change its resistance so that to keep a constant voltage across it (i.e., to apply a negative feedback).

* Third, we can apply the classic buffering solution connecting a voltage follower between the imperfect voltage divider source and the load thus supplying the load by a "copy" of the input voltage.

* Finally, if we are ingenious enough and we prefer sophisticated and eccentric circuit solutions:), we can cancel the load resistance by equal negative resistance:

https://en.wikibooks.org/wiki/Circuit_Idea/Revealing_the_Mystery_of_Negative_Impedance#Compensating_resistive_losses_by_N-shaped_negative_resistors

What do you think about all these techniques? Are they reliable? What is the best? Are there any other possible solutions of the problem?

I was inspired to ask this question by the contribution of Marcin Rutkowski in another "naive question" about the voltage divider:

https://www.researchgate.net/post/Is_the_voltage_divider_a_voltage_source_and_a_resistor-a_current_source_What_is_the_difference_between_them_and_the_true_electrical_sources

There is also a dual question about the creation of a perfect current source:

https://www.researchgate.net/post/What_is_current_source_Are_there_true_current_sources_If_not_how_do_we_create_artificial_current_sources_How_do_we_make_them_perfect2