1. MC34072DR2G Substitution Conclusion The MC34072DR2G is not recommended as a general-purpose direct substitute for the TL072CD. The core difference lies in its input stage architecture, which changes from J-FET to Bipolar. This results in critical electrical performance changes. The most significant distinction is the input bias current (100 nA vs. 65 pA), which is three orders of magnitude higher. In circuits such as those interfacing with high-impedance signal sources, integrators, or precision I-V converters, this will generate substantially larger input offset errors and DC drift. Furthermore, its input impedance is significantly lower than that of the J-FET type. While it offers advantages including a wider supply voltage range (3-44V), lower input offset voltage (1mV), and stronger output drive capability (30mA), these benefits are only meaningful in specific applications not requiring high input impedance. The feasibility of substitution is highly dependent on the specific circuit. Substitution may be considered if the original circuit does not rely on high-input-impedance characteristics and can tolerate the larger input bias current. Otherwise, it is not viable.