Say me the physical meaning of time const.?

Time constant of a low pass or high pass R-C circuit is ofcourse the product of R and C. but what it exactly do during circuit functioning?

Say me the physical meaning of time const.?
Suppose an electronic circuit is made of resistor, capacitor and with other elements, and we shall apply an input electrical signal to the circuit's input terminal. We expect that the signal at the output must change at the same time in synchronism to the input signal. Due to RC time constant, the response of the circuit-output will take some time. Ideally there should not be any time delay between the change of input and output signals. Thus RC time constant puts a limit on how fast input signal it can handle.
Reply:the easiest way to understant it is to present your low-pass circuit with a 0 1 signal.


When the input is 0, the output is 0.


The input changes to 1, the output stays 0 for a time, because the capacitor needs times to charge... it will take a time of about RC to get to 1...





that's the meaning of this time constant.





you can then easily understand that if you present your low pass filter with a signal of frequency %26gt; 1/RC, then it won't have enough time to shift to 1 before the input signal shifts back to 0... and the output signal will be a faded version of the input signal...








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in the case of a high pass filter, you want to have a variation of tension fast enough not to charge/discharge your capacitor, or all the tension would be located on the capacitor.


If you give enough time for the capacitor of a high pass filter to charge/discharge, then a differential of charge will appear in the capacitor and the input tension will be spent exclusively on the capacitor and not on the resistor... therefore, the output signal will be 0.








also: R and C are important in this constant, because the current will be proportional to R and it takes a duration proportional to C to charge a capacitor with a given current.

surveys