Oscilloscope, bread board set up, measuring phase / gain etc.

[js6]

Homework Statement

Hi,

I've been having trouble setting up an oscilloscope, with a AC voltage supply, to a breadbox, with a "black box" in the circuit. the black box is just a set of 3 pairs of terminals, each a "unknown component" such as a diode, capacitor, resistor, etc.

Basically I need to figure out how to properly construct the circuit to obtain values for phase, peak-peak voltage, etc using the oscilloscope, which would then allow me to determine the components. (Where to plug things in, such as the Ch.1 / Ch.2 of the oscilloscope, and the output of the AC voltage, with the board and the box.)

I was wondering if anyone has a diagram, or picture of such a set up that could help me, my attempts have been fairly basic, and encounter problems such as the grounding?

Thanks

 

[berkeman]

Homework Statement

Hi,

I've been having trouble setting up an oscilloscope, with a AC voltage supply, to a breadbox, with a "black box" in the circuit. the black box is just a set of 3 pairs of terminals, each a "unknown component" such as a diode, capacitor, resistor, etc.

Basically I need to figure out how to properly construct the circuit to obtain values for phase, peak-peak voltage, etc using the oscilloscope, which would then allow me to determine the components. (Where to plug things in, such as the Ch.1 / Ch.2 of the oscilloscope, and the output of the AC voltage, with the board and the box.)

I was wondering if anyone has a diagram, or picture of such a set up that could help me, my attempts have been fairly basic, and encounter problems such as the grounding?

Thanks

Welcome to the PF.

So can you say more about these black boxes? Are the 3 contacts basically the input, ground and output? And you are tasked with determining the transfer function Vout/Vin, and modeling it with discrete components?

Except for the diodes part, this is what the transfer function measurement does with impedance analyzers like the HP 4194. It has a swept AC excitation source, and a monitoring port that measures the transfer function (amplitude and phase) versus frequency. That is basically what you need to do manually with your signal generator and oscilloscope.

 

[nsaspook]

I think you are looking for a 'curve tracer' circuit. This is a simple "Octopus".
http://www.youtube.com/watch?feature=player_embedded&v=Gwo3pEH7hUE#

http://www.syscompdesign.com/AppNotes/curve-tracer.pdf

 

[js6]

Thanks for the replies,

The black box is just basic 2 terminals for each component, and yes I have to measure the gain (Vout/Vin) of the voltage drop over each unknown component, and other things such as phase. I understand what to expect from each component, however my problem lies in the actual set-up of the osscilloscope / AC generator / black box system,

I'll attach some pictures to show what I think I'll have to do, maybe someone can confirm the diagram is correct? Like I said, I understand what to expect from theory, it's just how to set-up the equipment with one another is my problem,

EDIT: Also, maybe if someone can clarify the exact purpose of the extra resistor, which would help a lot

Thanks again,

 

[paranormal]

I would suggest the following steps to properly set up your oscilloscope and breadboard for measuring phase and gain:

1. Make sure all components are properly connected and the circuit is complete. This includes connecting the AC voltage supply to the breadboard and the black box, and ensuring all components are securely plugged in.

2. Connect the ground lead of the oscilloscope to a ground point on the breadboard. This will help reduce noise and ensure accurate measurements.

3. Connect the probe of Channel 1 (Ch.1) of the oscilloscope to the input of the black box. This will allow you to measure the input voltage.

4. Connect the probe of Channel 2 (Ch.2) of the oscilloscope to the output of the black box. This will allow you to measure the output voltage.

5. Adjust the settings on the oscilloscope to measure AC voltage and set the time base to a suitable range for your signal.

6. Turn on the AC voltage supply and adjust the voltage to a suitable level for your circuit.

7. Use the cursors on the oscilloscope to measure the phase difference between the input and output signals. You can also use the peak-to-peak function to measure the amplitude (gain) of the signal.

8. Repeat the measurements for each pair of terminals on the black box to determine the components.

It may also be helpful to consult the manual for your specific oscilloscope and breadboard set up, as well as any information provided with the black box. Good luck with your measurements!