Input voltage protection

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injb
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Input voltage protection

Post by injb » Thu Nov 08, 2018 1:40 am

Hi, I just bought a 2405A and I have a question about the voltage limits. It says +/- 20v - is this independent of the voltage range I select in the picoscope software?

I ask because when I tried selecting the various ranges, I can hear it click for 200mv, 2v and 20v, so I presume there's some switching going on to scale my input to make the best use of the ADC's range. Supposing I'm looking at something that has a 20v spike, and then 2v section, and I want to zoom into the 2v part to get the best resolution. Can I safely set it to 2v, and just let the 20v part get clipped?

Thanks!

Martyn
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Re: Input voltage protection

Post by Martyn » Mon Nov 12, 2018 2:51 pm

Yes that is fine, the device overvoltage protection is ±100 V (DC + AC peak)
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injb
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Re: Input voltage protection

Post by injb » Mon Nov 12, 2018 3:56 pm

Martyn wrote:
Mon Nov 12, 2018 2:51 pm
Yes that is fine, the device overvoltage protection is ±100 V (DC + AC peak)
Thanks for the reply. I'm a bit confused though. Maybe I didn't phrase my question very well.

I read in another thread on this forum that you shouldn't rely on the overvoltage protection (see topic38081.html):
Although the overvoltage protection is ±50 V continued exposure to voltages over ±20V will cause damage, so you will need to use a voltage divider.
So what I'm trying to understand is, if I probe a signal of 20v while I have scale of lower than 20v selected in the software, does that count as 'overvoltage'?

Martyn
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Re: Input voltage protection

Post by Martyn » Tue Nov 13, 2018 6:19 am

The other thread was talking about looking at 24V signals so a significant amount of time the signal will be above the 20V range. You said 20V spikes, which are within the measurable range of the scope and so not overvoltage, and by nature would be short duration.
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