Current source circuit is an electronic circuit which deals with electric current. In this circuit current can be absorbed or delivered that is it acts as both source and sink. Current source may be dependent current source as well as independent current source. Independent current source circuit acts as current sink. Electric current is delivered at constant rate. Here the current is independent of the voltage across it.
Constant current source circuits are many. WE can form constant current source circuits in different ways. One of such circuit is formed from JFET that is junction field effect transistor. In this circuit gate is connected to its source. When JFET reaches saturation with constant current value then constant current diode is formed. This happens when drain to source voltage reaches a threshold value. Zener Diode current source is also available.
There are typical constant current source which uses LED instead of zener diode. In this type of circuit there is one limitation, it has imperfect thermal compensation. Constant current source circuit can be made with many analog blocks which include LEDs, op-amps, battery chargers. Also the circuit consists of voltage source, load, resistors and transistors. LED works well when constant current flows through it.
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