Digital Oscilloscope Maximum Input Voltage

[mike_mike]

Dear Forum,

I recently bought a new GDS-1052-U oscilloscope. I read a few pages from the oscilloscope manual and I found that the maximum input voltage is 300Vpeak.
I have a question regarding the maximum input voltage: 300V peak is the maximum voltage input for 10V/div or for 2mV/div using a 1x probe and AC coupling ?
The oscilloscope will be damaged if I set the vertical voltage to 2mV/div and connect the 1x probe to 200V peak ? I know that the 200V peak voltage cannot be displayed on the screen if the vertical voltage is 2mV/div, but I want to know what can happen ?
The last questions: what is the maximum DC input voltage, using a 1x probe and DC coupling ?
Thanks in advance,
Mike

[zvonex66x]

Maximum input voltage is 300V no metter if you set scale for 10V/div or 10mV/div...
At the input of your oscilloscope you can see maximun input voltage, but you need to see what is maximum voltage for your probe

[mike_mike]

Thanks for the reply.
What means "offset range bandwidth limit" ?
I found it in the manual and I took a screenshot:

The offset range bandwidth limit is the maximum voltage that can be applied at the input throught the 1x probe ?

[tggzzz]

Maximum input voltage is 300V no metter if you set scale for 10V/div or 10mV/div...
At the input of your oscilloscope you can see maximun input voltage, but you need to see what is maximum voltage for your probe

Not forgetting the max probe voltage as a function of signal frequency!

[tautech]

Thanks for the reply.
What means "offset range bandwidth limit" ?

They are two entirely different specs.

Offset Range. The amount the 0V of a channel can be offset (moved off screen) in order to display a waveform with a voltage offset.
Bandwidth Limit. Typically 20 MHz. Used to exclude the HF components of a signal and/or to clean up the waveform.

[mike_mike]

Thanks for the reply.
So the "offset range bandwidth limit" doesn't mean the maximum input voltage ? The maximum input voltage is 300V peak as it is mentioned in the manual ?

[tautech]

Thanks for the reply.
So the "offset range bandwidth limit" doesn't mean the maximum input voltage ?

Nothing to do with it at all.

The maximum input voltage is 300V peak as it is mentioned in the manual ?

Yes, it applies to a 1:1 probe or direct cable connection.

Study your probe pamphlet, don't push the limits of stated voltages and understand the frequency derating graph as tggzzz alluded to in his reply.

If you wish to extend the input voltage get a 100:1 or higher probe or for those with limited scope experience, a differential probe.

[Zero999]

Thanks for the reply.
What means "offset range bandwidth limit" ?
I found it in the manual and I took a screenshot:

The offset range bandwidth limit is the maximum voltage that can be applied at the input throught the 1x probe ?

I've not seen that before and I'm not certain. It looks like a maximum of +/-0.4V on settings equal or below 50mV/div, max +/-4V on settings between 100mV(10mV is probably an error) and 500mV/div, max of +/-40V, on settings from 1V/div to 5V/div and +/-300V on 10V/div.

[mike_mike]

Thanks for the reply.
I asked the question from the first post on another forum (before asking the question here) and some of the people from that forum said that if I will set de probe to 1x and the oscilloscope to 2mV/div (AC or DC coupling) and connect the probe to 200V peak, the oscilloscope will be damaged. Is that true ?
I am a beginner and this is my first digital scope so I am worried not to damage the scope when I work with it.

[Zero999]

Thanks for the reply.
I asked the question from the first post on another forum (before asking the question here) and the people from that forum said that if I will set de probe to 1x and the oscilloscope to 2mV/div and connect the probe to 200V peak, the oscilloscope will be damaged. Is that true ?
I am a beginner and this is my first digital scope so I am worried not to damage the scope when I work with it.

Yes, the specification indicates that, although hopefully, the input protection circuity should prevent any damage, although it's not a certainty.

[tautech]

Thanks for the reply.
I asked the question from the first post on another forum (before asking the question here) and the people from that forum said that if I will set de probe to 1x and the oscilloscope to 2mV/div and connect the probe to 200V peak, the oscilloscope will be damaged. Is that true ?

Maybe.
It's not standard practice to use probes set to 1:1, instead 10:1 is most often used.
In the channel menu set the input to the attenuation to match the probe then the OSD values will be correct.

Like any measurement device you can bust it if it's not set correctly so don't go anywhere near HV until you know exactly what you are doing.
At ~50V you can't get into too much trouble but for starters even stay a little lower until you are confident in usage. RTFM from front to back, 2 or 3 times, do simple tests to understand usage and become familiar with the controls.

As much as I hate it, Auto set is useful for scope newbies like you.

[mike_mike]

I read a part of the manual and I searched in the manual for some key words, but there is not mentioned the maximum voltage for the 2mV/div input.
If I will use the scope at a maximum voltage of 100V peak with the 1x probe and 2mV/div should be ok ? For example I am thinking that I will make a mistake and put the probe to 200V peak, with the 1x probe and 2mV/div. The scope will be damaged ?

[tautech]

I read a part of the manual and I searched in the manual for some key words, but there is not mentioned the maximum voltage for the 2mV/div input.
If I will use the scope at a maximum voltage of 100V peak with the 1x probe should be ok ?

For what good reason ?
Why even think about stressing the inputs of a scope with HV and 1:1 probes ? 

[mike_mike]

I am thinking that I will make a mistake..
For example I have a linear power supply and I want to measure ripple on 2mV/div with 1x probe and AC coupling, and the output of the power supply is 30Vdc.

[tautech]

I am thinking that I will make a mistake..
For example I have a linear power supply and I want to measure ripple on 2mV/div with 1x probe and AC coupling, and the output of the power supply is 30Vdc.

Then how you approach the measurement technique will minimize the chance of a mistake.

Who said you must use 2mV/div ?
Who said you must use 1:1 probe ?

Engage some little thought. Check first at a higher V/div setting then increase the sensitivity searching for the ripple. Never jump into a measurement at high sensitivity settings, never !!

[tggzzz]

I am thinking that I will make a mistake..
For example I have a linear power supply and I want to measure ripple on 2mV/div with 1x probe and AC coupling, and the output of the power supply is 30Vdc.

One easy way to make a mistake is to have a *1/*10 switchable probe. Sooner or later the switch will be in the wrong position.

Fortunately that is easy to avoid.

[glarsson]

Fortunately that is easy to avoid.

How? My standard probes are *10 but sometimes *1 would be nice. Have not found any *1 probes for sale! Hot glue in the switch doesn't solve all problems as the switch can become flaky.

[Zero999]

Fortunately that is easy to avoid.

How? My standard probes are *10 but sometimes *1 would be nice. Have not found any *1 probes for sale! Hot glue in the switch doesn't solve all problems as the switch can become flaky.

Get a x10 probe without a switch.

I read a part of the manual and I searched in the manual for some key words, but there is not mentioned the maximum voltage for the 2mV/div input.

Yes there is. It's in the screen shot you previously linked to and I explained it above. I repeat the maximum voltage rating is +/-0.4V on settings equal or below 50mV/div. Use a x10 probe if you want to use it on your 30V supply.

[glarsson]

Get a x10 probe without a switch.

How does that help?
I already have plenty of nice and expensive x10 probes without switches. What I don't have is a x1 probe without a switch.

[oldway]

I am thinking that I will make a mistake..
For example I have a linear power supply and I want to measure ripple on 2mV/div with 1x probe and AC coupling, and the output of the power supply is 30Vdc.

Why use an oscilloscope to measure the ripple on a linear power supply?

The ripple of a linear power supply is either 50Hz (60Hz) or 100Hz (120Hz), this can easily be measured with a multimeter on the AC range.
Some multimeters can also measure the frequency of the ripple.

With switching power supplies, it is better to use an oscilloscope because the frequency of the ripple is often too high for the multimeter.

[tggzzz]

Fortunately that is easy to avoid.

Have not found any *1 probes for sale!

Oh Good Grief.

https://www.digikey.se/products/en/test-and-measurement/test-leads-oscilloscope-probes/629?k=oscilloscope+probe&k=&pkeyword=oscilloscope+probe&pv331=270&FV=ffe00275&mnonly=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

That wasn't too difficult.

[GBowes]

I read a part of the manual and I searched in the manual for some key words, but there is not mentioned the maximum voltage for the 2mV/div input.

Yes there is. It's in the screen shot you previously linked to and I explained it above. I repeat the maximum voltage rating is +/-0.4V on settings equal or below 50mV/div. Use a x10 probe if you want to use it on your 30V supply.

Sorry, but I must suggest that this is not correct.
The Maximum input voltage to the BNC connectors on this scope is the 300V referenced previously.

Tautech had it correct about Offset Range yesterday so I am not sure how the question came back up.

The "Offset Range" has nothing to do with safe Maximum Voltage Inputs. It simply specifies how far the zero voltage reference point may be moved to try to get the trace on the screen.
The "bandwidth limit" is just the next line in a long list of specifications and has no bearing on the input voltage. In this case it is saying that this scope has a 20MHz Bandwidth Limit switch. When enabled, this will attenuate higher frequencies in the input signal.

The fact remains that some of the voltages in question can be dangerous and should be avoided until one has a complete understanding and familiarity with the operation and application of any measurement instruments.

Graham

Thanks for the reply.
What means "offset range bandwidth limit" ?
I found it in the manual and I took a screenshot:

The offset range bandwidth limit is the maximum voltage that can be applied at the input throught the 1x probe ?

I've not seen that before and I'm not certain. It looks like a maximum of +/-0.4V on settings equal or below 50mV/div, max +/-4V on settings between 100mV(10mV is probably an error) and 500mV/div, max of +/-40V, on settings from 1V/div to 5V/div and +/-300V on 10V/div.

[Zero999]

I read a part of the manual and I searched in the manual for some key words, but there is not mentioned the maximum voltage for the 2mV/div input.

Yes there is. It's in the screen shot you previously linked to and I explained it above. I repeat the maximum voltage rating is +/-0.4V on settings equal or below 50mV/div. Use a x10 probe if you want to use it on your 30V supply.

Sorry, but I must suggest that this is not correct.
The Maximum input voltage to the BNC connectors on this scope is the 300V referenced previously.

Tautech had it correct about Offset Range yesterday so I am not sure how the question came back up.

The "Offset Range" has nothing to do with safe Maximum Voltage Inputs. It simply specifies how far the zero voltage reference point may be moved to try to get the trace on the screen.
The "bandwidth limit" is just the next line in a long list of specifications and has no bearing on the input voltage. In this case it is saying that this scope has a 20MHz Bandwidth Limit switch. When enabled, this will attenuate higher frequencies in the input signal.

The fact remains that some of the voltages in question can be dangerous and should be avoided until one has a complete understanding and familiarity with the operation and application of any measurement instruments.

Graham

Thanks for the reply.
What means "offset range bandwidth limit" ?
I found it in the manual and I took a screenshot:

The offset range bandwidth limit is the maximum voltage that can be applied at the input throught the 1x probe ?

I've not seen that before and I'm not certain. It looks like a maximum of +/-0.4V on settings equal or below 50mV/div, max +/-4V on settings between 100mV(10mV is probably an error) and 500mV/div, max of +/-40V, on settings from 1V/div to 5V/div and +/-300V on 10V/div.

Thank you for your answer. To be honest, I wasn't sure about it when I posted it. I made more of a big deal about it, because I wanted someone to either confirm or correct it.

Yes, that makes much more sense. An instrument rated to 300V peak, is rated to that voltage on all settings.

[mike_mike]

Thanks for the replies.
I noticed a thing that I cannot explain: while the probe and the oscilloscope is set on 1x the noise from one power supply is about 5-6mV pp, while the probe and the oscilloscope is set on 10x, the noise from the same power supply (a LM317 power supply with PNP pass transistor) is about 50-60mV (see the images below, the first image with 1x probe and scope and the second with 10x probe and scope). Is that normal ?

[zvonex66x]

Yes, it's normal but you have changr probe from 1x to 10x but you didn't change probe in your oscilloscope settings