RC time constant and Oscilliscope

[Grim Tuesday]

So I am in a PLTW class, digital electronics. We are using Multisim 11 to simulate a circuit proving the RC time constant. However, there is one major problem: Multisim does not prove the constant. In this circuit when the total charge time should be 50, it is 100 in Multisim. Why does this inaccuracy exist, and how can I make it not? Note that at where it should be 100% charged, it is not, as shown in screenshot below.

[Tayyab_R]

Hi,

Please post the actual Multisim circuit so we can take a look at what is causing this issue.

[Grim Tuesday]

Sure thing! Thanks for looking into it.

[Mahmoud_W]

Hi,

I looked into the circuit and there is nothing wrong with it, the delay constant by definition is the time that would take the circuit to reach 66% of its maximum value and is equal to R*C. In your case R*C=10ms and the delay shown if you subtract the values of the markers in the attached figure is 10ms.

Hope this helps,

Mahmoud Wahby

Product Marketing Engineer

NI