one 1 k, two 10 k, and one 100 k 1/4 W resistor, 0.0047 F and 0.033 F capacitors, two 1N914 (or similar) silicon signal diodes, 2N3904 and 2N3906 transistors. Fig. 8.1: Generalized op amp ...

After a brief review of the history of the K2-W vacuum-tube op amp, an LTspice model is used to create its schematic in ...