Current Source vs. Voltage Source: Key Differences Explained

This article breaks down the fundamental differences between current sources and voltage sources, both essential components in electronics.

Current Source

Figure 1 illustrates the concepts of ideal and practical current sources.

Ideal Current Source: An ideal current source maintains a constant current flow regardless of the voltage across it. Think of it as a perfect current regulator, always delivering the same amperage no matter what.

Practical Current Source: Real-world current sources aren’t perfect. They have a large internal resistance, which means the actual current output will vary slightly depending on the voltage across the component it’s powering. The current isn’t completely constant; it changes a bit with variations in voltage.

In essence, a practical current source’s current output is dependent on the voltage.

Voltage Source

Figure 2 shows ideal and practical voltage sources.

Ideal Voltage Source: An ideal voltage source provides a constant voltage, no matter how much current is drawn from it. It’s like having a battery that never weakens, always delivering the same voltage.

Practical Voltage Source: Like current sources, real-world voltage sources aren’t perfect. They have a small internal resistance. This means the voltage across the element powered by the source will vary slightly based on the current flowing through it. As more current is drawn, the voltage drops a little.

In simple terms, the voltage across the element will vary based on the current demand.

Key Differences Summarized