Why does the AWG signal drop when I connect the ground lead to 0V in an RC circuit?

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confused.com
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Why does the AWG signal drop when I connect the ground lead to 0V in an RC circuit?

Post by confused.com »

I have a simple series RC circuit consisting of 100 ohm resistor and 1uF capacitor. AWG is set to an amplitude of 1.41Vac. If I connect this input signal to my capacitor, then capacitor to resistor and finally resistor to 0V bus on my breadboard and leave the ground reference clip floating, I can see that I have the desired sine wave displayed. As soon as I connect the ground clip to the 0v the signal drops to around 280mV. Does anybody know the reason for this? I have never used an oscilloscope before so please forgive me if I am being slightly dim :oops: . I just want to be able to show the input signal and voltage across the capacitor. I am using Picoscope 2204a if this has any significance. Any help would be greatly appreciated as I am pulling my hair out.

bennog
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Re: Why does the AWG signal drop when I connect the ground lead to 0V in an RC circuit?

Post by bennog »

because the output impedance of the sig gen is 600 ohm.

if you want it to be 0 ohm the you need a amplifier between the sig gen and your test setup.

but a amplifier with 0 ohm output blows up if you short circuit it because the current would be infinite.

Benno

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