Author Topic: Can a high voltage signal harm a scope because of a wrong setting?  (Read 1557 times)

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Offline mrjazz

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Imagine an oscilloscope can display for instance 40V peak to peak with the highest vertical Volts/div setting. Can I harm the oscilloscope when it is set to the lowest Volts/div setting (for instance 500uV/div) while having this 40Vpp signal fed into it? In other words, do I have to care about the vertical setting before connecting a high voltage source?
 

Pippy

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Re: Can a high voltage signal harm a scope because of a wrong setting?
« Reply #1 on: June 28, 2013, 08:24:24 pm »
Depends on the scopes input circuitry really. Without knowing the exact input circuit no one can really say for sure. The chances are it'll be fine though, but don't quote me on that!

Does the scope specs not mention anything about maximum input voltage range etc?

If in doubt, set your scope probe to x10 to start with, and if your likely to get high spike values leave it at x10.
« Last Edit: June 28, 2013, 08:41:35 pm by Pippy »
 

Offline G7PSK

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Re: Can a high voltage signal harm a scope because of a wrong setting?
« Reply #2 on: June 28, 2013, 08:52:54 pm »
All the scopes that I have seen state the maximum input voltage around the BNC socket. On mine it says 300 Volts PP+DC, This seems to be the voltage level on most scopes or at least all the ones I have looked at, the only time I have seen different was on a USB scope and that was 5 volts only, which is one reason such scopes are useless. I presume that as the maximum Volts/Division on my scope is 5 volts that the 300 volts PP must be the protection level, after all you can use a 10 or a 100 times probe and go to kilovolt probes as well.
 

Offline mrjazz

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Re: Can a high voltage signal harm a scope because of a wrong setting?
« Reply #3 on: June 29, 2013, 01:21:21 am »
Depends on the scopes input circuitry really. Without knowing the exact input circuit no one can really say for sure.
It is a Rigol DS2202.
All the scopes that I have seen state the maximum input voltage around the BNC socket.
So you say I only have care about this protection level stated on the front of the scope, but not the current vertical V/div setting?
 

Offline IanB

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Re: Can a high voltage signal harm a scope because of a wrong setting?
« Reply #4 on: June 29, 2013, 01:29:51 am »
So you say I only have care about this protection level stated on the front of the scope, but not the current vertical V/div setting?

Items of test equipment like scopes ought to be designed with a degree of robustness and tolerance to out of range inputs and operating mishaps. So as long as you don't exceed the specified maximum input voltage you should be OK. You might overload the input amplifiers, but they will just saturate and recover after you remove the overload (but there is no guarantee of signal fidelity under these circumstances).
I'm not an EE--what am I doing here?
 


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