As the title, what is the role of R3? Why can't the coupling capacitor at the input end be added after removing it, otherwise the oscilloscope waveform will run away.
Nathan ポストする August 7, 2020
The non-inverting input terminal of the op amp has an offset current. If R3 is not added, the non-inverting input terminal is equivalent to an open circuit, and its resistance is very large, which will damage the op amp.
Mia ポストする August 7, 2020
Pull down the potential of the same direction terminal to stabilize the input terminal.
Jordan ポストする August 7, 2020
The capacitor is open circuit for DC signals. If R3 is not added, for DC signals, the input terminal of the op amp is floating, and the op amp will not have a stable working state.
