What is the best equipment to obtain the correct I and V of an RC Circ 2

[pybb3ezv]

This is an ongoing question I have for which I still have not found a satisfactory answer. This concerns measurements with oscilloscopes in general and to understand it I am considering one of the simplest model circuits -- the RC circuit. Suppose you have a 10Ohm resistor and a 100pF capacitor in this RC circuit and you apply 800kHz of 8ppV amplitude. I have asked a question regarding this circuit earlier in this forum and I remained with the impression that studying such model circuit even with the state of the art equipment is so unreliable that the I and V data obtained hardly reflect the real I and V that would be expected theoretically. Is that the case? Is it really true that there is no equipment at present that would provide true I and V? If it isn't then what exact equipment (oscilloscope and probes) would you recommend that would yield true current and voltage of the said sine curves measured across the capacitor and the resistor, with all parasitic effects (capacitances and inductances) at a negigible level?

 

[IRstuff]

I dispute that it's not possible to make this measurement. For a measley $500K, I will make this measurement. Whether it's worth $500K for you to make this measurement is up to you.

I mean, we're talking about 0.8 AMPs of current, for crying out loud. People have been able to make even more difficult measurements involving 100 AMPs, with even less headroom.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[pybb3ezv]

@IRstuff, can you give reference to support this statement: "People have been able to make even more difficult measurements involving 100 AMPs, with even less headroom"?

 

[IRstuff]

Look at ANY laser diode driver that has current control. Since most circuits are proprietary, I will leave it to your ingenuity to find such circuits. However, I will tell you that a virtual ground might be involved.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[pybb3ezv]

@IRstuff, evidently you cannot provide evidence to sustain your claim that people have been able to make even more difficult measurements. I don't doubt that in all other aspects people have made all kinds of difficult measurements. However, in that particular aspect we're discussing here there's no evidence that they have.

 

[IRstuff]

Well, that's your opinion alone. I don't have to give you proprietary information just to satisfy your apparent whim. I've already given the basis for my statement, which, because you are not an engineer, you've completely failed to recognize the significance thereof. That's on you, not me.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[pybb3ezv]

That's for others to judge. What I see is that I'm not getting a satisfactory answer to my question other that such measurement is impossible to be made at present and therefore that part of the theory has never been confirmed experimentally.

 

[davidbeach]

One last attempt. The answer is that you're in the range in which simple instruments can't make sufficiently detailed measurements to confirm a nice neat theory. The theory is well proven and accepted. At larger values and lower frequencies, you can get there with simple instruments, but not where you want to be. At the values you want to work at, there is no such thing as a capacitor that exhibits only capacitance, nor is there such a thing as a resistor that exhibits only resistance. Theory and real world aren't the same thing. Measurements affect that which is being measured. Accept the theory, use it, but also accept all the "fudges" necessary to get theoretical results using real components.

If the theory didn't work, there would be many devices that do work that wouldn't. Can't you accept that?

Why not worry about chemical problems instead of trying to reprove well established electrical principals?

 

[pybb3ezv]

Thanks.