How it is possible to make a constant current source?

ANSWER: one way tie a zener x volts from B+ to ground with a resistor. that gives you a reference voltage using an PNP tie the base to the reference voltage collector goes to the load and the emitter is tied to +B trough a resistor Since the emitter follows the base then the current should be +B volts -zener voltage - Vbe or .6 v. that is it.