6
\$\begingroup\$

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: Is 300V peak the maximum voltage input for 10V/div or for 2mV/div using a 1x probe and AC coupling?

Will the oscilloscope 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 question: What is the maximum DC input voltage, using a 1x probe and DC coupling?

\$\endgroup\$

3 Answers 3

13
\$\begingroup\$

The maximum voltage is ±300V, period.

It doesn't matter what the settings on the scope are, or whether the voltage is AC or DC.

Any voltage less than that will not damage the scope, but what you see on the display may or may not be useful, depending on the settings.

You can use a 10× probe to measure higher voltages — up to whatever the probe is rated for — but if you ever switch the probe to 1× while doing so, you'll be violating the scope specification.

\$\endgroup\$
5
  • \$\begingroup\$ Thanks for the reply. What means "offset range bandwidth limit" ? I saw this in the manual: imgur.com/LB1cvYr \$\endgroup\$
    – beard999
    Jan 21, 2018 at 18:02
  • \$\begingroup\$ So the "offset range bandwidth limit" doesn't mean the maximum input voltage ? \$\endgroup\$
    – beard999
    Jan 21, 2018 at 19:03
  • \$\begingroup\$ "Offset range bandwidth limit" is actually two separate specifications: "Offset Range" (the top line) tells you how far the trace can be offset from zero for the various vertical scale settings. "Bandwidth Limit" (the bottom line) simply tells you the -3dB bandwidth of the scope overall. \$\endgroup\$
    – Dave Tweed
    Jan 21, 2018 at 19:17
  • \$\begingroup\$ Can you be more explicit ? I don't really understand. The offset range bandwidth limit is the maximum voltage allowed at the input of the oscilloscope or the maximum input voltage is 300Vpeak ? \$\endgroup\$
    – beard999
    Jan 21, 2018 at 19:22
  • \$\begingroup\$ For example, on any of the ranges from 2mV/div through 50mV/div, you will be able to bring any voltage between +/-0.4V to the center of the screen using the vertical offset control. That's what "offset range" means. \$\endgroup\$
    – Dave Tweed
    Jan 21, 2018 at 21:31
9
\$\begingroup\$

Dont confuse multiple specs. Separate them. enter image description here

enter image description here

See below datasheet on p139 enter image description here

The DSO measurement capability spec is 300V AC+DC , THIS MEANS that you can measure 300V off the screen by using the vertical offset dial.

A different item is the human safety limit " 300V CAT II" but is capable of withstanding the standard 2.5kV impulse test

This assumes the x1 probe.

There are safety measurement zones called Category I,II,III,IV... **

This instrument is only rated for CAT II. Beyond this can be fatal to the user at the same voltage.

  • CAT I is safe low voltage & current.
  • CAT II is 300V max but limited to protected residential outlets. but IEC certification tests include exposure to 2.5kV impulse tests.
  • CAT III is inside the breaker panel ( ie. connected to grid with greater risks)
    • which is restricted for use with this instrument, even though it is the same voltage.

** This is due to ARC Flash prevention limits due to energy , current limit and protection categories to prevent fatal measurements in CAT III e.g. spontaneous human combustion. ( sorry to be so graphic )

\$\endgroup\$
3
  • \$\begingroup\$ Does even Category II guarantee that the instrument will not be damaged by the specified overload, or only that there is no danger of shock, fire, or false negative readings? \$\endgroup\$ Jan 21, 2018 at 21:04
  • \$\begingroup\$ 300V CAT II means no damage to instrument and can actually measure 300V and display with offset \$\endgroup\$ Jan 21, 2018 at 21:44
  • \$\begingroup\$ "The DSO measurement capability spec is 300V AC+DC , THIS MEANS that you can measure 300V off the screen by using the vertical offset dial." So this means that if I connect the input to 200V AC + DC using an 1x probe and the scope configured on 2mV/div then the scope will not be damaged ? \$\endgroup\$
    – beard999
    Jan 22, 2018 at 6:50
1
\$\begingroup\$

I once measured an 800V waveform with a standard 10 to one scope probe. I built an adapter to connect between the scope and the probe. The adapter was a resistor in parallel with the 1MΩ of the scope input and a parallel capacitor. This caused more voltage drop across the 9MΩ resistor at the tip of the probe. I had to work with the cap value to get a clean square wave using the scope calibrator. And I also had to place a brass shield around the adapter to make it operate properly. I may have been lucky with the shield as once I tried that, it worked perfectly as a 2 to 1 adapter. I suspect my resistor was a 1MΩ in parallel with the 1MΩ scope impedance. The cap, I don't know. HA!! I still have it after 25+ years. I'll post a picture. It is covered with heatshrink, so I measured the resistor at 952kΩ and the cap at 105pf. enter image description here

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.