Electronics > Beginners
Digital Oscilloscope Maximum Input Voltage
David Hess:
--- Quote from: mike_mike on January 28, 2018, 04:45:55 pm ---I noticed that there is a delay from the moment I connect the probe to the calibration signal and the moment when the signal appears on the screen. Also there is a delay from the moment I disconnect the probe and the moment when the signal disappears from the screen. Is that normal ?
--- End quote ---
That is the same delay I discussed. The display is only updated after the record is filled.
mike_mike:
Thanks for the reply.
I saw another thing on my oscilloscope: while I am measuring the output of an LM317 + pnp transistor power supply I see on the screen a signal with the peak to peak voltage about 70mVpp measured by the scope, but when I am measuring the signal on the screen using the grid, the waveform has an peak to peak amplitude of about 55-60mVpp. While I am measuring this the time base is set on 2.5nS, and the voltage/div is set on 20mV. Is that normal or my scope does not measure correctly ?
Later Edit: I think I found the problem. I tried to measure again and it seems that the scope measures voltage correct.
mike_mike:
What acquisition mode should be used on the oscilloscope ? I can choose between Normal, Average and Peak Detect. Which is the best ?
Also, when I am using Average I can select a number from 2 to 256. If I select 256, the trace is at first very noisy and it getting less noisy in a few seconds:
Average 256, when I connect the probe to the LM317 power supply:
https://imgur.com/a/LE8ZF
Average 256, after about 10 seconds:
https://imgur.com/a/MWcZr
Average 256, after about another 10 seconds:
https://imgur.com/a/QfPwn
It is normal for the trace to be more noisy at the moment when I connect it to the signal source ? And after a few seconds to get less noisy ?
tggzzz:
--- Quote from: mike_mike on February 03, 2018, 03:37:11 pm ---What acquisition mode should be used on the oscilloscope ? I can choose between Normal, Average and Peak Detect. Which is the best ?
--- End quote ---
Each is best in different circumstances. That is all explained in many places on the web; I suggest starting with Tektronix and Agilent application notes.
There's no point in us spending our precious time giving a (poor) explanation to you, if you can't be bothered to spend some time finding high quality answers. Google is your friend.
mike_mike:
Thanks for the reply.
When measuring the noise from an LM317 or LM723 power supply, I saw that in one day, the noise was about 24mVpp for the LM723 power supply and about 50mVpp for the LM317 power supply. A few days later, I measured again the noise from the same power supplies, and I found that the LM723 had noise about 40mVpp and the LM723 had noise about 55mVpp. Is that normal ? Why the noise whas lower in one day and higher in another day ?
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