A Constant-Current Source is an electronic circuit which, ideally, delivers a constant current to any load, irrespective of its resistance. In other words, it is a current regulator. However, in practice, a constant current source cannot deliver an infinite current to a load. It is limited in its capabilities by the voltage supplied to it and the power dissipation capabilities of the circuit components; therefore, it cannot supply any amount of current to any load. Moreover, it cannot maintain the exact, same amount of current through the load. Small variations in the delivered current is inevitable, but the variations are low and can be further minimised. In this project, the circuit is realised using transistors and resistors. Two LEDs, with a Normally Open (NO) switch in parallel to one of them, is used to simulate a variable load. On closing or opening the switch (Push Button), an LED is bypassed or reconnected to the output of the circuit, simulating a variable load. Irrespective of this, the circuit pumps the same amount of current through the load, with a very small and acceptable error in regulation. **Please read the attached doccument for full details.** Everycircuit simulation: https://everycircuit.com/circuit/5204466287247360 (desktop) http://everycircuit.com/circuit/5204466287247360 (android app)