Timeline for Why is there no resistor at the input in below op amp circuit which converts sine wave into square?
Current License: CC BY-SA 4.0
4 events
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| Jun 7, 2018 at 13:44 | comment | added | Bimpelrekkie | indeed and a feedback loop relies on the output being able to influence the input in some way. If that's not possible then it is not feedback. That forgotten resistor makes the influence possible. Without the resistor there can be no "proper" feedback. It is a shame it was not included because it is essential. | |
| Jun 7, 2018 at 13:41 | comment | added | Dave Tweed | Putting the Zener diodes in the feedback loop has the huge advantage of preventing the opamp itself from saturating, which preserves its performance. Many opamps take a long time to come out of saturation, which can lead to very poor performance in the overall circuit. | |
| Jun 7, 2018 at 13:35 | comment | added | AgentS | Ahh so the input resistor is a must to limit the current. Such a relief! Thank you. I wish they had put that zenar diode structure parallel to the output. (I can't help feeling that the author wants to show off how clever he is by using the virtual ground at the - input. ) Thanks again :) | |
| Jun 7, 2018 at 13:24 | history | answered | Bimpelrekkie | CC BY-SA 4.0 |