1. MC34074VDR2G Substitution Conclusion The MC34074VDR2G can serve as a partially compatible substitute in general-purpose applications where input bias current is non-critical, and where a wider supply voltage range or stronger output drive capability is required. However, it cannot directly replace the TL084ID in critical applications involving high-impedance signal sources, precision integration, or micro-current sensing. The key distinctions are: 1) Its input bias current (100nA vs. 30pA) is three orders of magnitude higher, which will introduce significant DC error in high-source-impedance circuits—this reflects the fundamental difference between bipolar and JFET input stages; 2) Its supply voltage range (3-44V vs. 10-30V) is wider, offering greater flexibility for both low-voltage single-supply systems and higher-voltage rails; 3) Its output current (30mA vs. 10mA) is higher, providing better drive capability for capacitive or low-impedance loads; 4) Its input offset voltage (1mV vs. 3mV) is superior, which aids DC accuracy, but this benefit is overshadowed by its significantly larger input bias current effect. The viability of substitution is highly dependent on the specific circuit's sensitivity to input current precision.