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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DC-DC converter from low voltage at high current, to high voltage at low current
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;
$begingroup$
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.
- At low frequency (say 100 Hz), the output is good
- At high frequency (say 5 kHz), the output is too bad.
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
edited 29 mins ago
Peter Mortensen
1,60031422
asked 8 hours ago
NihalNihal
467
$endgroup$
add a comment |
$begingroup$
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.
- At low frequency (say 100 Hz), the output is good
- At high frequency (say 5 kHz), the output is too bad.
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
edited 29 mins ago
Peter Mortensen
1,60031422
asked 8 hours ago
NihalNihal
467
$endgroup$
$begingroup$
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
8 hours ago
4
$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
8 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
8 hours ago
$begingroup$
Yes i used the scope probe only at the output. I don't know which causing this error.......@Jimmy
$endgroup$
– Nihal
8 hours ago
$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
7 hours ago
add a comment |
$begingroup$
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.
- At low frequency (say 100 Hz), the output is good
- At high frequency (say 5 kHz), the output is too bad.
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
edited 29 mins ago
Peter Mortensen
1,60031422
asked 8 hours ago
NihalNihal
467
$endgroup$
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.
- At low frequency (say 100 Hz), the output is good
- At high frequency (say 5 kHz), the output is too bad.
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
edited 29 mins ago
Peter Mortensen
1,60031422
asked 8 hours ago
NihalNihal
467
edited 29 mins ago
Peter Mortensen
1,60031422
asked 8 hours ago
NihalNihal
467
edited 29 mins ago
Peter Mortensen
1,60031422
edited 29 mins ago
Peter Mortensen
1,60031422
edited 29 mins ago
Peter Mortensen
1,60031422
1,60031422
asked 8 hours ago
NihalNihal
467
asked 8 hours ago
NihalNihal
467
asked 8 hours ago
NihalNihal
467
467
$begingroup$
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
8 hours ago
4
$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
8 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
8 hours ago
$begingroup$
Yes i used the scope probe only at the output. I don't know which causing this error.......@Jimmy
$endgroup$
– Nihal
8 hours ago
$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
7 hours ago
add a comment |
$begingroup$
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
8 hours ago
4
$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
8 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
8 hours ago
$begingroup$
Yes i used the scope probe only at the output. I don't know which causing this error.......@Jimmy
$endgroup$
– Nihal
8 hours ago
$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
7 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
8 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
8 hours ago
4
4
$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
8 hours ago
$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
8 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
8 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
8 hours ago
$begingroup$
Yes i used the scope probe only at the output. I don't know which causing this error.......@Jimmy
$endgroup$
– Nihal
8 hours ago
$begingroup$
Yes i used the scope probe only at the output. I don't know which causing this error.......@Jimmy
$endgroup$
– Nihal
8 hours ago
$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
7 hours ago
$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
7 hours ago
add a comment |
5 Answers
5
active
oldest
votes
$begingroup$
The recommendations for you are very simple.
Use a comparator for this application instead of an opamp.
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.
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
$endgroup$
$begingroup$
Sure friend i will change the opp amp or by using comparator, i will update the data soon.
$endgroup$
– Nihal
8 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
7 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
4 hours ago
1
$begingroup$
@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
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
|
show 5 more comments
$begingroup$
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.
answered 8 hours ago
user287001user287001
9,6441517
$endgroup$
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
1
$begingroup$
@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
8 hours ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
add a comment |
$begingroup$
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.
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
$endgroup$
1
$begingroup$
Yes, and/or phase inversion, depending on the op-amp type.
$endgroup$
– Peter Mortensen
2 hours ago
add a comment |
$begingroup$
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?
edited 5 hours ago
Renan
4,32222244
answered 8 hours ago
AutisticAutistic
7,49921633
$endgroup$
add a comment |
$begingroup$
You may try this, if you want a discrete solution
simulate this circuit – Schematic created using CircuitLab
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
add a comment |
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5 Answers
5
active
oldest
votes
5 Answers
5
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
The recommendations for you are very simple.
Use a comparator for this application instead of an opamp.
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.
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
$endgroup$
$begingroup$
Sure friend i will change the opp amp or by using comparator, i will update the data soon.
$endgroup$
– Nihal
8 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
7 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
4 hours ago
1
$begingroup$
@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
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
|
show 5 more comments
$begingroup$
The recommendations for you are very simple.
Use a comparator for this application instead of an opamp.
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.
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
$endgroup$
$begingroup$
Sure friend i will change the opp amp or by using comparator, i will update the data soon.
$endgroup$
– Nihal
8 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
7 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
4 hours ago
1
$begingroup$
@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
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
|
show 5 more comments
$begingroup$
The recommendations for you are very simple.
Use a comparator for this application instead of an opamp.
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.
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
$endgroup$
The recommendations for you are very simple.
Use a comparator for this application instead of an opamp.
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.
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
edited 7 hours ago
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
answered 8 hours ago
Michael KarasMichael Karas
45.2k348105
answered 8 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
8 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
7 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
4 hours ago
1
$begingroup$
@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
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
|
show 5 more comments
$begingroup$
Sure friend i will change the opp amp or by using comparator, i will update the data soon.
$endgroup$
– Nihal
8 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
7 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
4 hours ago
1
$begingroup$
@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
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
$begingroup$
Sure friend i will change the opp amp or by using comparator, i will update the data soon.
$endgroup$
– Nihal
8 hours ago
$begingroup$
Sure friend i will change the opp amp or by using comparator, i will update the data soon.
$endgroup$
– Nihal
8 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
7 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
7 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
4 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
4 hours ago
1
1
$begingroup$
@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
3 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
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
$begingroup$
LM741 might still be in the textbooks...
$endgroup$
– Peter Mortensen
3 hours ago
|
show 5 more comments
$begingroup$
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.
answered 8 hours ago
user287001user287001
9,6441517
$endgroup$
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
1
$begingroup$
@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
8 hours ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
add a comment |
$begingroup$
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.
answered 8 hours ago
user287001user287001
9,6441517
$endgroup$
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
1
$begingroup$
@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
8 hours ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
add a comment |
$begingroup$
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.
answered 8 hours ago
user287001user287001
9,6441517
$endgroup$
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.
answered 8 hours ago
user287001user287001
9,6441517
answered 8 hours ago
user287001user287001
9,6441517
answered 8 hours ago
user287001user287001
9,6441517
answered 8 hours ago
user287001user287001
9,6441517
9,6441517
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
1
$begingroup$
@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
8 hours ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
add a comment |
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
1
$begingroup$
@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
8 hours ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
$begingroup$
Thank you for your response friend, i will update it after changing the opp amp.
$endgroup$
– Nihal
8 hours ago
1
1
$begingroup$
@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
8 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
8 hours ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
$begingroup$
Ok friend I will even buy a comparator and I will check with it.
$endgroup$
– Nihal
1 hour ago
add a comment |
$begingroup$
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.
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
$endgroup$
1
$begingroup$
Yes, and/or phase inversion, depending on the op-amp type.
$endgroup$
– Peter Mortensen
2 hours ago
add a comment |
$begingroup$
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.
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
$endgroup$
1
$begingroup$
Yes, and/or phase inversion, depending on the op-amp type.
$endgroup$
– Peter Mortensen
2 hours ago
add a comment |
$begingroup$
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.
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
$endgroup$
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.
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
answered 7 hours ago
Scott SeidmanScott Seidman
22.7k43286
answered 7 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
2 hours ago
add a comment |
1
$begingroup$
Yes, and/or phase inversion, depending on the op-amp type.
$endgroup$
– Peter Mortensen
2 hours ago
1
1
$begingroup$
Yes, and/or phase inversion, depending on the op-amp type.
$endgroup$
– Peter Mortensen
2 hours ago
$begingroup$
Yes, and/or phase inversion, depending on the op-amp type.
$endgroup$
– Peter Mortensen
2 hours ago
add a comment |
$begingroup$
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?
edited 5 hours ago
Renan
4,32222244
answered 8 hours ago
AutisticAutistic
7,49921633
$endgroup$
add a comment |
$begingroup$
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?
edited 5 hours ago
Renan
4,32222244
answered 8 hours ago
AutisticAutistic
7,49921633
$endgroup$
add a comment |
$begingroup$
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?
edited 5 hours ago
Renan
4,32222244
answered 8 hours ago
AutisticAutistic
7,49921633
$endgroup$
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?
edited 5 hours ago
Renan
4,32222244
answered 8 hours ago
AutisticAutistic
7,49921633
edited 5 hours ago
Renan
4,32222244
edited 5 hours ago
Renan
4,32222244
edited 5 hours ago
Renan
4,32222244
4,32222244
answered 8 hours ago
AutisticAutistic
7,49921633
answered 8 hours ago
AutisticAutistic
7,49921633
answered 8 hours ago
AutisticAutistic
7,49921633
7,49921633
add a comment |
add a comment |
$begingroup$
You may try this, if you want a discrete solution
simulate this circuit – Schematic created using CircuitLab
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
add a comment |
$begingroup$
You may try this, if you want a discrete solution
simulate this circuit – Schematic created using CircuitLab
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
add a comment |
$begingroup$
You may try this, if you want a discrete solution
simulate this circuit – Schematic created using CircuitLab
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
You may try this, if you want a discrete solution
simulate this circuit – Schematic created using CircuitLab
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
answered 3 hours ago
analogsystemsrfanalogsystemsrf
16k2822
16k2822
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
add a comment |
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
$begingroup$
What is it? A Schmitt trigger?
$endgroup$
– Peter Mortensen
3 hours ago
add a comment |
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$begingroup$
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
8 hours ago
4
$begingroup$
Why you shouldn't use the 741.
$endgroup$
– JRE
8 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
8 hours ago
$begingroup$
Yes i used the scope probe only at the output. I don't know which causing this error.......@Jimmy
$endgroup$
– Nihal
8 hours ago
$begingroup$
You're latching up.
$endgroup$
– Scott Seidman
7 hours ago