Hi. I need to be able to find the value of the following capacitor and resistor. The circuit is in a box so I only have access to node1, node2 and ground. I am not allowed to use an oscilloscope. I can only apply voltages and measure voltage or current at the output.

N1 o-----||-----o N2
           |
           R
           |
     o----------o Gnd

 

Well, measuring the resistor should be straightforward enough, so I'm assuming you're trying to measure the capacitor.

By far the easiest way to do that is to measure the RC time constant and calculate the capacitance from there. Without an oscilloscope, though, I don't know how you'd possibly get an accurate measure of the time constant.

What can you use to measure voltage/current? What can you use to supply voltage? If you have a function generator, you could probably make a rough estimate by finding the frequency cutoff of your circuit (it's a high pass filter).

 

Well, measuring the resistor should be straightforward enough, so I'm assuming you're trying to measure the capacitor.

By far the easiest way to do that is to measure the RC time constant and calculate the capacitance from there. Without an oscilloscope, though, I don't know how you'd possibly get an accurate measure of the time constant.

What can you use to measure voltage/current? What can you use to supply voltage? If you have a function generator, you could probably make a rough estimate by finding the frequency cutoff of your circuit (it's a high pass filter).

I'd definitely go for the cutoff frequency method.

eric

 

Only able to apply dc or ac 10 V. measurements made using an adc which is interfaced with a xilinx chip.

 

Can you vary the freq. of your 10VAC? Also, if you can record the voltage measurements on the FPGA fast enough, you could measure the RC response.