Before revision: Non-linear characteristics Input breakdown voltage The transistors Q3, Q4 help to increase the reverse VBE rating : the base-emitter junctions of the NPN transistors Q1 and Q2 break down at around 7V, but the PNP transistors Q3 and Q4 have VBE breakdown voltages around 50V.The μA741 Operational Amplifier Output-stage voltage swing and current limiting Variations in the quiescent current with temperature, or between parts with the same type number , are common, so crossover distortion and quiescent current may be subject to significant variation.
After revision: Non-linear characteristics Input breakdown voltage The transistors Q3, Q4 help to increase the reverse VBE rating ; The base-emitter junctions of the NPN transistors Q1 and Q2 break down at around 7V, but the PNP transistors Q3 and Q4 have VBE breakdown voltages around 50V.The μA741 Operational Amplifier Output-stage voltage swing and current limiting Variations in the quiescent current with temperature, or due to manufacturing variations , are common, so crossover distortion may be subject to significant variation.