Non-Inverting Zero Crossing Detector
In non – inverting Zero Crossing Detector the input voltage Vin is applied at the positive node of the op-amp and the reference voltage that is zero is applied at the negative node of the op-amp. In the non inverting zero crossing detector output of the given circuit goes into positive saturation when the applied input voltage is positive and output goes to negative when input voltage is negative, the circuit diagram of non inverting zero crossing detector is given below.
Circuit Diagram of Non-Inverting Zero Crossing Detector
The figure given below represents the circuit diagram of Non-Inverting Zero Crossing Detector. In this circuit we have used inverting op-amp. Here , the input voltage Vin is given in the non- inverting terminal of the op-amp and inverting terminal of op-amp is grounded.
Working of Non-Inverting Zero Crossing Detector
As per definition it detects the point where the input signal is ZERO because it’s reference voltage is 0. Before start the working of Non-Inverting Zero Crossing Detector we have to let the output voltage is +V sat.
Now see the circuit to understand the working.
As per circuit reference voltage is 0 which is applied at the inverting terminal of op-amp which is compared with Vin which is applied at the non – Inverting terminal of op-amp.
Now when positive half of the sinusoidal wave appears at the input and op-amp comparator compares its peak level with the reference voltage.
Vo = Vin – V ref
because the reference voltage is 0, so
Vo = Vin – 0
as we have already mentioned that starting output voltage is (+V sat), so
Vo = (+V sat) – 0
Vo = (+V sat).
Now when the negative half of the sinusoidal wave appears at the input and op-amp compares its peak level with the reference voltage.
So,
Vo = V ref – Vi
Vo = 0 – (+ V sat )
We get
Vo = (-V sat )
Here we can clearly see that how a NON – INVERTING Zero Crossing Detector detects the changes in the level of applied input sinusoidal signal.
Input and Output Waveform
In the beginning we have already mentioned that Zero Crossing Detector is also known as a Square Wave generator. Same as the output of the Window Comparator is nothing but a Square Wave.
Now Let us see how a Non-Inverting Zero Crossing Detector generate the Square Wave or Output waveform.
in the working part we have derived that Vo for the positive half of the sinusoidal signal is (+V sat). because of this we get Positive output for the positive half of the applied signal. while Vo for the negative half of the applied input signal is (-V sat). because of this we get negative output for the negative half of the applied signal.
Zero Crossing Detector
A voltage comparator circuit whose output changes concerning the input signal which is crossing the zero of the reference voltage level that’s why it is called a Zero Crossing Detector. These circuits are commonly known as switching circuits the output of these circuits lies between positive and negative saturation voltage levels. The most commonly used circuits are the Schmitt trigger, Astable, and Monostable Multivibrators.
Table of Content
- What is a Zero Crossing Detector?
- Types
- Inverting Zero Crossing Detector
- Non-Inverting Zero Crossing Detector
- Applications
- Advantages and Disadvantages
- Comparsion Between Comparator and Schmitt Trigger