Ideal Voltage Source?

The concept of an ideal voltage source is pretty simple,

* An ideal voltage source is a voltage source that maintains the same voltage across the source's terminals no matter what current is drawn from the terminals of the source or what current flows into the terminals.

That's it in a nutshell. If the source is a DC Source, we can plot a voltage current plot for an ideal voltage source. The plot is shown below. However, we need to define terms. Here is a circuit symbol for an ideal voltage source. In this symbol, we assume the following.

* The voltage across the terminals is denoted as Vt.
* The load current flowing from the source to a load (presumably a load is attached when the source is in a circuit) is denoted as IL.
* With those definitions, here is the source symbol. It's just a circle with polarity indicated.

And, here is the plot of terminal voltage against load current.

Given the discussion above, we can say:

* Vt = constant, no matter what the load current is.

That's pretty much the description of the ideal voltage source. It's not too complex, but it is an important concept. In the next section we'll look at how you can put this concept to use. For the rest of this section we'll look at ideal current sources starting next.