# Schematic Circuit Diagram Op-Amp as Zero-Crossing detector proteus simulation

When the input signal is connected to V+ and V- is grounded, as the input voltage rises above the ground voltage i.e, when the input is positive, the output of the Op-Amp is +V*sat* and the output is –V*sat* while the input is negative.

**Op-Amp as a Non-Inverting Zero-Crossing detector**

Alternatively, when the input signal is connected to V- and V+ is grounded, as the input voltage rises above the ground voltage i.e., when the input is positive, the output of the Op-Amp is -V*sat* and the output is +V*sat* while the input is negative. This difference is used when the input signal is obtained from the secondary of a transformer, and square wave output is to be used for some other applications.

**Op-Amp as Inverting Zero-Crossing detector**

However, suitable filter circuits must be inserted between the input signal and the Op-Amp circuit in order to eliminate harmonics.

**v = V sin ωt**, where v is the voltage at time t and V is the maximum voltage.

**y=Y sin ωt**, i.e. amplitude Y and angular frequency ω, as being produced by a radial line of length Y rotating with a constant angular velocity ω (Figure 11.2), taking the vertical projection y of the line at any instant of time to represent the value of the sinusoidal signal.