When inputting 18A, the waveform changes. Why is this?

嘻哈嘻哈

When inputting 18A, the waveform changes. Why is this? [Copy link]

 

maychang

[When inputting 18A, the waveform changes. Why is this?]

What is your op amp supply voltage?

maychang

[When inputting 18A, the waveform changes. Why is this?]

The input peak is 254V, and R1 is 10 kilo-ohms. Can you calculate the current flowing through R1? This current is equal to the output current of the op amp. Can your op amp output such a large current?

吾妻思萌

If the op amp has overcurrent, you can change the resistor and try the control variable method. Once you try it, you will know which component is wrong.

呜呼哀哉

The output of this op amp is saturated, which causes it to fail to clamp and produce phase inversion. You can just increase VCC and VCC- amplification.

嘻哈嘻哈

VCC seems to be unable to be amplified. I want to enter the 51 microcontroller, so I set 5v

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Azuma Simeng posted on 2024-11-5 08:33 If the op amp is overcurrent, you can change the resistor and try the control variable method. Once you try it, you will know which original part is wrong

Good, good.

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maychang posted on 2024-11-5 07:21 [When inputting 18A, the waveform changes. Why is this?] What is the power supply voltage of your op amp?

VCC is 5V, because it needs to be put into the 51 microcontroller

lkh747566933

Input 18W? It doesn't look like 18A in your properties panel.

maychang

Hi Ho Hi Ho posted on 2024-11-5 10:39 VCC is 5V, because it needs to be put into the 51 microcontroller

OP07 is not a rail-to-rail op amp. When the load resistance is 10 kilo-ohms, the output voltage is 2.5V lower than the positive voltage of the power supply at most and 2.5V higher than the negative voltage of the power supply at most, so the output swing is only plus or minus 2.5V. When the load resistance is 1 kilo-ohm, the output swing is only plus or minus 2V or even less.

maychang

Hi Ho Hi Ho posted on 2024-11-5 10:39 VCC is 5V, because it needs to be put into the 51 microcontroller

You want to put the op amp output into the 51 microcontroller? The 51 microcontroller does not have analog input (AD input). If the OP07 outputs positive 2V, it cannot drive the 51 microcontroller I/O port.

It is recommended to switch to a rail-to-rail op amp.

In addition, the R1 value in the first post should be increased to 10 times.

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maychang posted on 2024-11-5 10:57 You want to put the op amp output "into the 51 microcontroller"? The 51 microcontroller does not have analog input (AD input). If the OP07 outputs positive 2V, it will not...

OK, then I'll try the rail-to-rail op amp. I added a digital-to-analog converter and collected a few hundred millivolts. The simulation is OK and I can measure the value, but I don't know if there will be any problems with the actual product.

嘻哈嘻哈

lkh747566933 posted on 2024-11-5 10:53 Input 18W? It looks like your property panel is not 18A.

This is the effective value of current. The English version is RMS, and then I translated it into power.

lkh747566933

Hi Ho Hi Ho posted on 2024-11-6 21:36 This is the effective value of current. The English version is RMS, and then I translated it into power after Chinese translation

You don't even check it, it's hard to see