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Beginners issues

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Beginners issues

Postby skyflyer » Mon Jul 13, 2015 9:14 pm

So, I've been working with the Pico now, measuring stuff. I have a few questions:

1) The box says +- 20Vpk max - I assume this means I must not deliver more than + or - 20V to the input channel, unless I'm using n-X probe, which drops the voltage for me. I'm just wondering, what happens in practice, if some spike comes along (say 50V) and you're using 1x probe?

2) Sometimes, picoscope 6 (using the beta 6.11.4.929) does not take measurements. For instance, check out this screenshot:
Image
Data available here: http://drop.v-m-a.net/uploads/gnd-motor-2.psdata

On some buffers, I get measurement, on some, I don't. I have not figured out the discriminators yet...

3) When using single trigger - is there a way to fill up more buffers? I.e., to somehow specify that I'd like to "record" 10 buffers after the trigger happened? It records only one and then stops. I know I can define a different timebase and then zoom into it -- but is this really the same as filling up buffers?

Thanks!
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Re: Beginners issues

Postby Martyn » Tue Jul 14, 2015 1:53 pm

In answer to your questions
1. There is over voltage protection, ±100 V (DC + AC peak), which means you won't damage the scope, but you won't get a reading as it would be off scale. However it is not sensible to leave constant over voltages applied to the scope.

2. If you look carefully at the trace you will see it has gone above the 10V range, therefore the measurement for that buffer is not possible.

3. It would be better to chose a different timebase and zoom in as this would give a continuous data set. If you try to use multiple buffers you would either need a trigger for each buffer with the trigger set to Repeat, or you would have gaps of 1 second with it set to Auto.
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Re: Beginners issues

Postby skyflyer » Tue Jul 14, 2015 2:42 pm

Martyn wrote:2. If you look carefully at the trace you will see it has gone above the 10V range, therefore the measurement for that buffer is not possible.


That's a shame. Even though it goes off-scale, I would expect the measurment (maximum, in this case) to measure the maximum, which is 10V). Is there a specific reason why this is not implemented, or am I misunderstanding your answer? To paraphrase, if the voltage goes over the range, the (automatic) measurement is not calculated?

Martyn wrote:3. It would be better to chose a different timebase and zoom in as this would give a continuous data set. If you try to use multiple buffers you would either need a trigger for each buffer with the trigger set to Repeat, or you would have gaps of 1 second with it set to Auto.


OK, so time-base setting it is.
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Re: Beginners issues

Postby Martyn » Tue Jul 14, 2015 2:48 pm

If the voltage is off scale then it is impossible to say what the actual voltage is, so reporting a maximum reading of 10V would be inaccurate.
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