So I'm working on a project for a lab class where I need to measure the voltage drop across a resistor using one scope while using another to look at AWG1 set to ramp from 0 to five volts, to observe the point where the mosfet begins conducting.
We're using a zvn2110a as a voltage controlled current source with Vcc(set to 5V) positive line connected to one leg of a 100 ohm resistor, the other side on the drain side of the mosfet and ground on the source while using AWG1 as the gate control. Connecting the positive lead of Scope 1 to the Vcc side of the resistor and the ground line to the mosfet drain side of the resistor
The problem I'm running into is that Is that when looking at the the scope output I get a flat line at 5V, like it's just reading VCC to gorund , instead of getting the observed drop across the resistor. Hooking up my standalone scope I can see the expected v-drop curve over the resistor as AWG1 ramps up, but not using the electronics explorer o-scope. After poking about I noticed that ALL of my grounds, including those for the scope channels, are all at the same potential(0V).
Now If I pull the ground entirely of the scope channel and put the sense lead at the drain of the mosfet I get the trace I expect for measuring over the mosfet, which is mirror of what I should see over the resistor in the same interval.
Is there something I'm missing here? How can I get the scope ground to act independently for each channel rather than act like its tied to a global ground?
(Attached images to show setup and scope outputs from EE board)
Question
Damian Wolfe
So I'm working on a project for a lab class where I need to measure the voltage drop across a resistor using one scope while using another to look at AWG1 set to ramp from 0 to five volts, to observe the point where the mosfet begins conducting.
We're using a zvn2110a as a voltage controlled current source with Vcc(set to 5V) positive line connected to one leg of a 100 ohm resistor, the other side on the drain side of the mosfet and ground on the source while using AWG1 as the gate control. Connecting the positive lead of Scope 1 to the Vcc side of the resistor and the ground line to the mosfet drain side of the resistor
The problem I'm running into is that Is that when looking at the the scope output I get a flat line at 5V, like it's just reading VCC to gorund , instead of getting the observed drop across the resistor. Hooking up my standalone scope I can see the expected v-drop curve over the resistor as AWG1 ramps up, but not using the electronics explorer o-scope. After poking about I noticed that ALL of my grounds, including those for the scope channels, are all at the same potential(0V).
Now If I pull the ground entirely of the scope channel and put the sense lead at the drain of the mosfet I get the trace I expect for measuring over the mosfet, which is mirror of what I should see over the resistor in the same interval.
Is there something I'm missing here? How can I get the scope ground to act independently for each channel rather than act like its tied to a global ground?
(Attached images to show setup and scope outputs from EE board)
Link to comment
Share on other sites
2 answers to this question
Recommended Posts
Archived
This topic is now archived and is closed to further replies.