The input resistance $${R_{IN}}\left( { = {V_x}/{I_x}} \right)$$ of the circuit in the figure is

In the Schmitt trigger circuit shown in figure, if $${V_{CE}}\left( {sat} \right) = 0.1V,$$ the output logic low level $$\left( {{V_{OL}}} \right)$$ is

Assuming the operational amplifier to be ideal, the gain $${V_{out}}/{V_{in}}$$ for the circuit shown in figure

The output voltage$$\left( {{V_0}} \right)$$ of the Schmitt trigger shown in figure swings between $$+15V$$ and $$–15V.$$ Assume that the operational amplifier is ideal. The output will change from $$+15V$$ to $$–15V$$ when the instantaneous value of the input sine wave is