I would like to state the problem I am dealing with which I cannot explain.
The set up I have is as follows:
- 2 x resistors 1 kΩ,
- 1 x breadboard,
- 1 x Voltcraft DSO-6202FM oscilloscope which has 2 channels and dual channel arbitrary function generator.
I have a breadboard where I built a resistor voltage divider of two 1k Ohm resistors. At one end of the first resistor I connected a probe coming from the function generator. The signal from the function generator is a square wave at 200 Hz, start phase 0 degrees, a high level 500 mV, low level 0 mV. A probe is used to display the output signal at the measuring point and is connected to channel 1 CH1 of the oscilloscope.
When I connect the output probe from the function generator to the probe connected to CH1 directly, I see a square wave, without needing to connect the two ground clips of both probes.
Q. How is this possible? I thought I need to connect the ground clips together to have a common ground and then be able to see the waveform from the function generator!
As shown in the diagram above, the output of the function generator is connected to the one end of the first 1 kΩ resistor. The probe of CH1 is connected to the output resistor of the voltage divider. The second end of the output resistor is NOT connected to a common ground. A signal is recorded but the value of which is the same as in the first observation. If I connect the ground clip of the function generator, the ground clip of CH1 and the second end of the output resistor together, the recorded waveform on CH1 of the oscilloscope is constant 0 volt.
Q. What is the explanation of this phenomenon that when I connect all the ground clips and the resistor of the voltage divider together to form ground I get a 0 volt signal on the oscilloscope?
Your wise comments and suggestions are welcomed with high regards.