Electronics and Communication Engineering - Exam Questions Papers - Discussion

5. 

Consider the Schmitt trigger circuit shown below. A triangular wave which goes from - 12 V to 12 V is applied to the inverting input of the op-amp. Assume that the output of the op-amp moves from +15 V to -15 V. The voltage at the non-inverting switches between

[A]. -12 V and +12 V
[B]. -7.5 V and +7.5 V
[C]. -5 V and +5 V
[D]. 0 V and 5 V

Answer: Option B

Explanation:

V0 is switching between + 15 to - 150

Thus voltage at non-inverting input switches between

, 7.5 to - 7.5 .


Sree said: (Jun 23, 2016)  
If the answer is 7.5. Then what is the need for the top resistor (10k)?

Milan Sharma said: (Sep 15, 2017)  
It should be -5 to 5 because the top resistor also affects the beta and beta will be 10/(30) i.e 1/3.

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