I am new to using oscilloscopes. When I was consistently getting zero voltage in an experiment I was doing, I decided to test whether my oscilloscope was working properly.

I set up a very simple circuit consisting of only a power supply at 3 volts and a resistor. However, the measurement on the oscilloscope of the voltage drop across the resistor remains jittering around zero.

enter image description here enter image description here Increasing the voltage causes a brief increase in the reading before it falls back down to zero. Is there something I am doing wrong or is the oscilloscope faulty?

  • 5
    \$\begingroup\$ Have you got the input set to AC coupling instead of DC? \$\endgroup\$ Mar 20 at 14:13
  • 6
    \$\begingroup\$ You appear to be looking at channel 2 and not channel 1. Channel 1 is connected to a scope probe but ch 2 isn't. \$\endgroup\$
    – Andy aka
    Mar 20 at 14:15
  • \$\begingroup\$ And then yet another basic thing to check: ensure that the channel is configured to the same attenuation as the probe. If the probe says 10x then the channel needs to be 10x as well. Otherwise all voltages will be shown wrong by a power of 10. \$\endgroup\$
    – Lundin
    Mar 20 at 16:05
  • \$\begingroup\$ Tip: most oscilloscopes have a built in square wave source, called the calibrator. On yours, the output is on the lower right hand corner of the front and is a loop intended for you to hook your probe on to. This is a convenient way to check for basic problems. \$\endgroup\$
    – user71659
    Mar 21 at 1:10

1 Answer 1


Both channels are set to AC from your image. The ~ sign denotes AC.

enter image description here

You need to switch to DC in the scope settings.


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