voltagesource

A voltage source, sometimes called a voltagesource, is a circuit element that establishes a potential difference between its two terminals and provides power to a circuit. In theory, it maintains a specified voltage regardless of current; in practice, real sources have finite internal resistance and current limits. Voltage sources are classified as independent, which fix their output, and dependent (controlled), whose voltage depends on another circuit variable.

Independent sources include DC supplies and batteries (constant voltages) and AC sources (time-varying voltages such as mains or function generators). An ideal voltage source has zero internal resistance, but real sources exhibit regulation errors, droop under load, and temperature effects.

In analysis, any voltage source with internal resistance is modeled as a Thevenin equivalent: an ideal voltage source in series with a resistance, or as a Norton equivalent, a current source in parallel with a resistance. Dependent voltage sources, such as voltage-controlled voltage sources, implement feedback and gain within circuits like op-amps.

Applications include biasing, signal generation, and powering electronic devices. Key specifications include nominal (open-circuit) voltage, output impedance, regulation, and maximum current. Knowledge of internal resistance is essential for predicting voltage under load and for safe operation.

Symbols and variants: an independent voltage source is drawn as a circle with plus and minus signs; a dependent source uses a diamond shape. Variants include DC, AC, and pulsating sources, and special forms such as isolated versus non-isolated supplies.