Operational amplifier as a comparator at high frequencyReasons not to use a 741 op-amp?Can I use LM324 as a Schmitt trigger?Simple op-amp differential amplifierOp amp has a biased outputReduced output of op amp peak detection and hold circuitHow to select the right Operational Amplifier as an impedance converter?Bias voltage of non-inverting op amplifier drops to 0 when input signal connectedHigh negative voltages with op-ampopamp output unstableComparator circuit undesirable fluctuations20kHz sine wave signal amplificationIf there exists a cascade of op amps, does the previous op amp's slew rate affect the later op amp's slew rates?

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Operational amplifier as a comparator at high frequency


Reasons not to use a 741 op-amp?Can I use LM324 as a Schmitt trigger?Simple op-amp differential amplifierOp amp has a biased outputReduced output of op amp peak detection and hold circuitHow to select the right Operational Amplifier as an impedance converter?Bias voltage of non-inverting op amplifier drops to 0 when input signal connectedHigh negative voltages with op-ampopamp output unstableComparator circuit undesirable fluctuations20kHz sine wave signal amplificationIf there exists a cascade of op amps, does the previous op amp's slew rate affect the later op amp's slew rates?






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








5












$begingroup$


I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

 = 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?






operational-amplifier comparator







share|improve this question











$endgroup$











  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    12 hours ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    12 hours ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    12 hours ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    11 hours ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    3 hours ago

















5












$begingroup$


I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

 = 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?






operational-amplifier comparator







share|improve this question











$endgroup$











  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    12 hours ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    12 hours ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    12 hours ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    11 hours ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    3 hours ago













5












5








5





$begingroup$


I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

 = 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?






operational-amplifier comparator







share|improve this question











$endgroup$




I am trying to generate a sinusoidal PWM signal using analog circuits.
I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs and slew rate 0.5 V/µs, which will good at 5 kHz theoretically. But I am not getting a good PWM output.



So I first tried to compare the sine wave with a reference voltage (2.2 volt). Sine wave amplitude = 2.5 volt (5 V peak to peak) and frequency 100 Hz and 5 kHz.



Enter image description here



  • At low frequency (say 100 Hz), the output is good

  • At high frequency (say 5 kHz), the output is too bad.

Enter image description here



Enter image description here



What will be the problem...



If the response is the problem of the comparator, but the slew rate is 0.5 V/µs.



Calculation of slew rate for a sinusoidal signal...



Slew rate= Vm * 2pi * Frequency



 = 5 V * 2pi* 5000 Hz

 = 1570796 volt per second or 0.15 V/µs


Theoretically the slew rate of 0.5 V/µs will be OK for a sinusoidal signal of 5 kHz and 5 volt peak to peak. But in my case the signal is distorted.



Where am I wrong?






operational-amplifier comparator




operational-amplifier comparator






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 4 hours ago









Peter Mortensen

1,60031422




1,60031422










asked 13 hours ago









NihalNihal

517




517











  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    12 hours ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    12 hours ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    12 hours ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    11 hours ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    3 hours ago
















  • $begingroup$
    It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
    $endgroup$
    – JimmyB
    12 hours ago






  • 5




    $begingroup$
    Why you shouldn't use the 741.
    $endgroup$
    – JRE
    12 hours ago










  • $begingroup$
    For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
    $endgroup$
    – Nihal
    12 hours ago







  • 1




    $begingroup$
    You're latching up.
    $endgroup$
    – Scott Seidman
    11 hours ago






  • 1




    $begingroup$
    Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
    $endgroup$
    – pipe
    3 hours ago















$begingroup$
It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
$endgroup$
– JimmyB
12 hours ago




$begingroup$
It looks like there's a significant lag/delay in the output's response w.r.t. the input signal (~30µs?). What may be causing this? What's connected to the output? 'Scope probe only?
$endgroup$
– JimmyB
12 hours ago




5




5




$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
12 hours ago




$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
12 hours ago












$begingroup$
For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
$endgroup$
– Nihal
12 hours ago





$begingroup$
For 5Khz i thought 741 will be ok, for what i calculated .Orelse sure i will change the opp amp which having high slew rate and i will update it.......@JRE
$endgroup$
– Nihal
12 hours ago





1




1




$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
11 hours ago




$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
11 hours ago




1




1




$begingroup$
Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
$endgroup$
– pipe
3 hours ago




$begingroup$
Note that this question is about the theory behind the calculations. Telling OP to change his OP-amp does nothing to answer the question. It just solves the problem without OP knowing why.
$endgroup$
– pipe
3 hours ago










5 Answers
5






active

oldest

votes


















8












$begingroup$

The recommendations for you are very simple.



  1. Use a comparator for this application instead of an opamp.


  2. Select a newer part that operates with orders of magnitude faster response time.


It would be the very best thing if the 741 could be eradicated from face of the earth.



Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



enter image description here



enter image description here






share|improve this answer











$endgroup$












  • $begingroup$
    Sure friend i will change the opp amp or by using comparator, i will update the data soon.
    $endgroup$
    – Nihal
    12 hours ago






  • 1




    $begingroup$
    @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
    $endgroup$
    – Michael Karas
    12 hours ago






  • 1




    $begingroup$
    "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
    $endgroup$
    – UKMonkey
    8 hours ago






  • 2




    $begingroup$
    @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
    $endgroup$
    – CurtisHx
    7 hours ago










  • $begingroup$
    LM741 might still be in the textbooks...
    $endgroup$
    – Peter Mortensen
    7 hours ago


















3












$begingroup$

Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






share|improve this answer









$endgroup$












  • $begingroup$
    Thank you for your response friend, i will update it after changing the opp amp.
    $endgroup$
    – Nihal
    12 hours ago






  • 2




    $begingroup$
    @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
    $endgroup$
    – user287001
    12 hours ago










  • $begingroup$
    Ok friend I will even buy a comparator and I will check with it.
    $endgroup$
    – Nihal
    5 hours ago


















1












$begingroup$

Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






share|improve this answer









$endgroup$








  • 1




    $begingroup$
    Yes, and/or phase inversion, depending on the op-amp type.
    $endgroup$
    – Peter Mortensen
    6 hours ago



















0












$begingroup$

Most garden variety op-amps have internal compensation in the form of a chip capacitor.



This makes them very slow, but more stable in analog circuits.



Why not use a cheap comparator like LM393?






share|improve this answer











$endgroup$




















    0












    $begingroup$

    You may try this, if you want a discrete solution





    schematic





    simulate this circuit – Schematic created using CircuitLab






    share|improve this answer









    $endgroup$












    • $begingroup$
      What is it? A Schmitt trigger?
      $endgroup$
      – Peter Mortensen
      7 hours ago











    Your Answer





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    5 Answers
    5






    active

    oldest

    votes








    5 Answers
    5






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    8












    $begingroup$

    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here






    share|improve this answer











    $endgroup$












    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      12 hours ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      12 hours ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      8 hours ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      7 hours ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      7 hours ago















    8












    $begingroup$

    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here






    share|improve this answer











    $endgroup$












    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      12 hours ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      12 hours ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      8 hours ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      7 hours ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      7 hours ago













    8












    8








    8





    $begingroup$

    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here






    share|improve this answer











    $endgroup$



    The recommendations for you are very simple.



    1. Use a comparator for this application instead of an opamp.


    2. Select a newer part that operates with orders of magnitude faster response time.


    It would be the very best thing if the 741 could be eradicated from face of the earth.



    Here is what can be achieved with the venerable LM393 at 5kHz. The shown circuit will work even up to about 50kHz before the delay of the LM393 starts to distort the PWM duty cycle.



    enter image description here



    enter image description here







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 12 hours ago

























    answered 12 hours ago









    Michael KarasMichael Karas

    45.2k348105




    45.2k348105











    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      12 hours ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      12 hours ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      8 hours ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      7 hours ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      7 hours ago
















    • $begingroup$
      Sure friend i will change the opp amp or by using comparator, i will update the data soon.
      $endgroup$
      – Nihal
      12 hours ago






    • 1




      $begingroup$
      @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
      $endgroup$
      – Michael Karas
      12 hours ago






    • 1




      $begingroup$
      "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
      $endgroup$
      – UKMonkey
      8 hours ago






    • 2




      $begingroup$
      @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
      $endgroup$
      – CurtisHx
      7 hours ago










    • $begingroup$
      LM741 might still be in the textbooks...
      $endgroup$
      – Peter Mortensen
      7 hours ago















    $begingroup$
    Sure friend i will change the opp amp or by using comparator, i will update the data soon.
    $endgroup$
    – Nihal
    12 hours ago




    $begingroup$
    Sure friend i will change the opp amp or by using comparator, i will update the data soon.
    $endgroup$
    – Nihal
    12 hours ago




    1




    1




    $begingroup$
    @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
    $endgroup$
    – Michael Karas
    12 hours ago




    $begingroup$
    @Nihal - If you show some new results in the question do not delete your original material, Instead add it as an update at the end. The reason for this is that hopefully this question can be a reference to future readers that are looking for information as being discussed here. If you delete the original material the answers here would no longer make much sense to a future reader.
    $endgroup$
    – Michael Karas
    12 hours ago




    1




    1




    $begingroup$
    "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
    $endgroup$
    – UKMonkey
    8 hours ago




    $begingroup$
    "It would be the very best thing if the 741 could be eradicated from face of the earth." ok - I'll bite. what's your reasons?
    $endgroup$
    – UKMonkey
    8 hours ago




    2




    2




    $begingroup$
    @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
    $endgroup$
    – CurtisHx
    7 hours ago




    $begingroup$
    @UKMonkey the 741 was first released in 1968. And while it was a fantastic IC at the time, there are vastly superior op-amps available with lower input offset voltage, higher bandwidth, higher input impedance, etc. Most people lean the "ideal op-amp" first, and then immediately jump to one of the most non-ideal op-amps in practice, and wonder why their design doesn't work.
    $endgroup$
    – CurtisHx
    7 hours ago












    $begingroup$
    LM741 might still be in the textbooks...
    $endgroup$
    – Peter Mortensen
    7 hours ago




    $begingroup$
    LM741 might still be in the textbooks...
    $endgroup$
    – Peter Mortensen
    7 hours ago













    3












    $begingroup$

    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






    share|improve this answer









    $endgroup$












    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      12 hours ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      12 hours ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      5 hours ago















    3












    $begingroup$

    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






    share|improve this answer









    $endgroup$












    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      12 hours ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      12 hours ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      5 hours ago













    3












    3








    3





    $begingroup$

    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.






    share|improve this answer









    $endgroup$



    Opamps work slowly with low power supply voltages. In addition they are designed to work in linear region. As saturated, like in your application, the response has an unpredictable dead time. before the internal saturation is vanished.



    I can only repeat what's already said: Get a comparator. 741 was a remarkable step forward half a century ago, but things have developed better since those days.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 12 hours ago









    user287001user287001

    9,6541517




    9,6541517











    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      12 hours ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      12 hours ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      5 hours ago
















    • $begingroup$
      Thank you for your response friend, i will update it after changing the opp amp.
      $endgroup$
      – Nihal
      12 hours ago






    • 2




      $begingroup$
      @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
      $endgroup$
      – user287001
      12 hours ago










    • $begingroup$
      Ok friend I will even buy a comparator and I will check with it.
      $endgroup$
      – Nihal
      5 hours ago















    $begingroup$
    Thank you for your response friend, i will update it after changing the opp amp.
    $endgroup$
    – Nihal
    12 hours ago




    $begingroup$
    Thank you for your response friend, i will update it after changing the opp amp.
    $endgroup$
    – Nihal
    12 hours ago




    2




    2




    $begingroup$
    @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
    $endgroup$
    – user287001
    12 hours ago




    $begingroup$
    @Nihal Comparators have other precautions. They are high speed circuits like logic parts. You must have acceptably short wires and coupling capacitors between supply voltage inputs. Making the circuit with 0,5 meter long wires onto a breadboard without coupling caps (I have seen those attempts) will be useless.
    $endgroup$
    – user287001
    12 hours ago












    $begingroup$
    Ok friend I will even buy a comparator and I will check with it.
    $endgroup$
    – Nihal
    5 hours ago




    $begingroup$
    Ok friend I will even buy a comparator and I will check with it.
    $endgroup$
    – Nihal
    5 hours ago











    1












    $begingroup$

    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






    share|improve this answer









    $endgroup$








    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      6 hours ago
















    1












    $begingroup$

    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






    share|improve this answer









    $endgroup$








    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      6 hours ago














    1












    1








    1





    $begingroup$

    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.






    share|improve this answer









    $endgroup$



    Op-amps are susceptible to latch-up. Recovering from saturation at the rails is not an automatic thing. The ratings you are reading a for the op amp working in a feedback mode, not an open loop mode. You would need to find an op amp designed to minimize latch-up, or better yet, when you need a comparator, buy a comparator.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 11 hours ago









    Scott SeidmanScott Seidman

    22.7k43286




    22.7k43286







    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      6 hours ago













    • 1




      $begingroup$
      Yes, and/or phase inversion, depending on the op-amp type.
      $endgroup$
      – Peter Mortensen
      6 hours ago








    1




    1




    $begingroup$
    Yes, and/or phase inversion, depending on the op-amp type.
    $endgroup$
    – Peter Mortensen
    6 hours ago





    $begingroup$
    Yes, and/or phase inversion, depending on the op-amp type.
    $endgroup$
    – Peter Mortensen
    6 hours ago












    0












    $begingroup$

    Most garden variety op-amps have internal compensation in the form of a chip capacitor.



    This makes them very slow, but more stable in analog circuits.



    Why not use a cheap comparator like LM393?






    share|improve this answer











    $endgroup$

















      0












      $begingroup$

      Most garden variety op-amps have internal compensation in the form of a chip capacitor.



      This makes them very slow, but more stable in analog circuits.



      Why not use a cheap comparator like LM393?






      share|improve this answer











      $endgroup$















        0












        0








        0





        $begingroup$

        Most garden variety op-amps have internal compensation in the form of a chip capacitor.



        This makes them very slow, but more stable in analog circuits.



        Why not use a cheap comparator like LM393?






        share|improve this answer











        $endgroup$



        Most garden variety op-amps have internal compensation in the form of a chip capacitor.



        This makes them very slow, but more stable in analog circuits.



        Why not use a cheap comparator like LM393?







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited 9 hours ago









        Renan

        4,32222244




        4,32222244










        answered 12 hours ago









        AutisticAutistic

        7,49921633




        7,49921633





















            0












            $begingroup$

            You may try this, if you want a discrete solution





            schematic





            simulate this circuit – Schematic created using CircuitLab






            share|improve this answer









            $endgroup$












            • $begingroup$
              What is it? A Schmitt trigger?
              $endgroup$
              – Peter Mortensen
              7 hours ago















            0












            $begingroup$

            You may try this, if you want a discrete solution





            schematic





            simulate this circuit – Schematic created using CircuitLab






            share|improve this answer









            $endgroup$












            • $begingroup$
              What is it? A Schmitt trigger?
              $endgroup$
              – Peter Mortensen
              7 hours ago













            0












            0








            0





            $begingroup$

            You may try this, if you want a discrete solution





            schematic





            simulate this circuit – Schematic created using CircuitLab






            share|improve this answer









            $endgroup$



            You may try this, if you want a discrete solution





            schematic





            simulate this circuit – Schematic created using CircuitLab







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 7 hours ago









            analogsystemsrfanalogsystemsrf

            16k2822




            16k2822











            • $begingroup$
              What is it? A Schmitt trigger?
              $endgroup$
              – Peter Mortensen
              7 hours ago
















            • $begingroup$
              What is it? A Schmitt trigger?
              $endgroup$
              – Peter Mortensen
              7 hours ago















            $begingroup$
            What is it? A Schmitt trigger?
            $endgroup$
            – Peter Mortensen
            7 hours ago




            $begingroup$
            What is it? A Schmitt trigger?
            $endgroup$
            – Peter Mortensen
            7 hours ago

















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