Constant Current Source with BJT Transistor

These BJT transistor constant current source circuits can provide a reasonably constant current if precision isn't critical, such as driving LEDs. The advantage of a constant current source over a single resistor to drive LEDs is that the circuit can supply the same current while the supply voltage fluctuates, or as different LEDS (or a different number of LEDS) are swapped in the circuit. With just a resistor, the current would fluctuate as these other parameters change, which may not be desirable. BJT Transistor Biasing: https://en.wikipedia.org/wiki/Bipolar_transistor_biasing#Fixed_bias_(base_bias) Patreon: https://www.patreon.com/gadgetreboot