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# Tag Info

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A couple options. I'd recommend that you do a math channel and divide your output by your input. You can then turn on a measurement to measure the average of the math channel waveform. You could also do measurements on the waveforms themselves and do the division by hand/in your head.

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Using these reading from Agilent MSO-X2012a oscilloscope: and How do you calculate the close loop gain using these measurements. You can look in detail at the picture: - And see that channel 1 is about 11 times bigger than channel 2 i.e. gain is 1 + 10k/1k.

-2

The fine print in the manual says... Do not use the Average acquisition mode if the source signal contains frequencies of interest that are not synchronized with the trigger rate. p94 https://download.tek.com/manual/TDS3000C-Oscilloscope-User-Manual_071230807.pdf

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The problem is the scope has 10kpts which means every time it is triggered, it must take 10kpts and then the software must transfer those points out of the scope. The max trigger time is related to how many points your acquiring, my suggestion would be to use a fast acquisition mode if you have one on your scope (1000 pts). Another problem is if I'm not ...

2

You're basically correct. This is known as the scope's "resolution." For 99.9% digital oscilloscopes, the ADC only looks at the height of the screen and does not go off screen. For this reason, they also don't make measurements on signal data above or below the screen. So, you can take the "full scale" of the screen - the volts-per-division times the number ...

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When you measure by ordinary 10:1 probe method you get Vdm and Vcm and stray noise pickup on coax and ground clip from LC resonance from inputs < 20ns rise time. Thus resulting in poor signal capture test method. 1st try to measure the Vdm (Diff mode) noise accurately, then when you capture Vdm +Vcm with a single 10:1 to your reference earth ground you ...

1

In an SMPS on the DC power supply side, Common Mode (CM) noise occurs when current exits the circuit and returns through the ground. Typically a DC supply is not grounded in two places (although it could be) as shown in the circuit above, this creates a ground loop and causes problems. Typically noise exits a device through capacitance and then returns ...

-2

Based on your schematic, if you want to measure $V_{cm}$, there is no reason to connect anything except for a load to terminal B of the supply at all, just measure terminal A relative to the ground terminal of the supply. Even single-ended passive probes usually have both a signal and a ground connection. You would connect the probe ground with as short a ...

3

It means that (for instance) if you set both A and B input channels to 1V/div, and apply 1V at the specified frequency to channel A, you should not see more than 1% (i.e. 10mV) of that voltage on the other channel (which you probably wouldn't be able to see). It doesn't say whether the other input should be open or short circuit which might affect things - ...

3

I don't understand what meant by channel to channel isolation here "Isolation" means that a signal on channel 1 won't appear on the trace for channel 2 or vice versa. It doesn't mean that the signal input connections for channel 1 and channel 2 are isolated (although on some equipment this may be so). An isolation of 100:1 likely means that a 1 volt signal ...

2

sin(x)/x or sinc is the function of the ideal low pass filter. Your scope has a sharp cutoff at f/2 (at least you are prentending that), and using the ideal low pass filter for interpolation then gives you a result better matching the characteristics of that ideal scope than linear interpolation. Or in short: with sinc, you at least don't see such ...

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If I'm interpreting your first scope plot correctly it's showing switching noise from a SMPS running just under 100KHz. The apparent jitter is due to the fact that noise occurs on both edges of the switching waveform, so analysis of this waveform will show a fundamental at just under 200KHz, spread somewhat by the jitter on the switching edge. You can see ...

1

Looks like your oscilloscope input is saturating. The input will have a certain range and beyond that you need to add attenuation (as in a x10, x100 etc. probe) or you will get that effect (and can possibly damage the oscilloscope at some point, though most should be protected to a couple hundred volts peak or so). Try a x10 probe (and change the software ...

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Ensure that your "dottings" are correct. If your primary one are wrong you'd probably get magic smoke. If the secondaries are wrong it may be "interesting". You should get nothing but may get some low output, such as you are seeing. When the secondaries are operated individually do they produce the expected voltage. Join any two matching ends of the ...

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