In electronics, a constant current system is a system that can vary the voltage across an electronic circuit to maintain a constant electric current. When a component is indicated to be driven by a constant current, the driver circuit is, in essence, a current regulator and must appear to the component as a current source of suitable reliability.
An important usage of constant current power supplies is with LEDs. While a high series resistance is sufficient to light an LED, sometimes the design needs to guard against high current (or risk burning out the LEDs). Another use is in fluorescent lamps which have very dynamic electrical resistance and are optimally operated within a short range of currents. Other uses include shielded metal arc welding and gas tungsten arc welding.
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Famous quotes containing the words constant and/or current:
“The tears of the world are a constant quality. For each one who begins to weep, somewhere else another stops. The same is true of the laugh.”
—Samuel Beckett (1906–1989)
“The current flows fast and furious. It issues in a spate of words from the loudspeakers and the politicians. Every day they tell us that we are a free people fighting to defend freedom. That is the current that has whirled the young airman up into the sky and keeps him circulating there among the clouds. Down here, with a roof to cover us and a gasmask handy, it is our business to puncture gasbags and discover the seeds of truth.”
—Virginia Woolf (1882–1941)