Op-Amp - NPN BJT Current Source

Op-Amp - NPN BJT Current Source. Problem/s is/are expected to arise in this circuit. The feedback is from the collector of the BJT to the noninverting input of the op-amp. If the reference voltage is adjusted lower than about 1.8V, the output transistor enters saturation. The op-amp cannot maintain the negative feedback and the circuit will latch. It can resume to proper operation when the reference voltage is adjusted higher than the latched state voltage (about 4.2 V) at the noninverting input.