of either variety exist (all real-world examples have finite and non-zero source impedance), any current source can be considered as a voltage source with the same source impedance and vice versa. These concepts are dealt with by Norton's and Thévenin's theorems. Charging of capacitor by constant current source and by voltage source is different. Linearity is maintained for constant current source charging of capacitor with time, whereas voltage source charging of capacitor is exponential with time. This particular property of constant current source helps for proper signal conditioning with nearly zero reflection from load. See also Constant current Current limiting Current loop Current mirror Current sources and sinks Fontana bridge, a compensated current source Iron-hydrogen resistor Saturable reactor Voltage-to-current converter Welding power supply, a device used for arc welding, many of which are designed as constant current devices. Widlar current source References Further reading "Current Sources & Voltage References" Linden T. Harrison; Publ. Elsevier-Newnes 2005; 608-pages; External links Current Sources and Current Mirrors FET Constant-Current Source/Limiter - Vishay JFET Current Source and pSpice Simulation Using Current Sources / Sinks / Mirrors In Audio Differential Amplifiers and Current Sources Analog circuits Electric current Electrical power control