Measuring Intergrator Time Constant and Decay Time Constant

[stanleystan]

How do you measure an Intergrators Time constant?

To Measure an Intergrators Rate of change, you have to remove the input signal or intergrator reset?

Measuring the Intergrators Rate of change and Time constant is the same thing?

To Measure an output of a circuit or networks decay Time Constant , you remove the input and the output will rise rapidly to a peak voltage and decay towards zero.

Why would you want to measure the Decay time constant? to know how fast the RC network or output is discharging?

 

[BradtheRad]

The RC time constant is saying how much time a 63% change takes.

Often the C value is known. Sometimes R is known, and other times it cannot be measured directly.
R might be a combination of (a) visible components, and (b) unseen internal impedance in inputs/ outputs of neighboring devices.

R might be one value while a device is 'on', and it might be another value when that device is 'off'. The two might alternate through a cycle.

We might want to know the RC time constant because we're interested in a particular frequency range, or a sample-and-hold time, or a propagation delay, etc.

 

[LvW]

The RC time constant is saying how much time a 63% change takes.
.

I think, this applies to a lowpass time constant only (lossy integrator).

For an ideal integrating device applies the following:
* Time domain: The time constant T gives the time for the output voltage to reach exactly the value of the (constant) input voltage.
* Frequency domain: The transfer function crosses the 0 dB line at the frequency 1/T.

 

[stanleystan]

When I put my O-scope probe on the output of an intergrator output, how do i measure the intergrators time constant and the rate of change?

On the O-scope you will view the Slope or Ramp, how would you measure the intergrators time constant and rate of change?

What kind of circuits or networks got to a peak voltage and then decay after you remove the input signal?

 

[BradtheRad]

When I put my O-scope probe on the output of an intergrator output, how do i measure the intergrators time constant and the rate of change?

On the O-scope you will view the Slope or Ramp, how would you measure the intergrators time constant and rate of change?

On my old scope I must observe a waveform's drop, and measure it according to the grid divisions and time divisions. There are newer models that show readouts of volt levels, min/max, etc.

What kind of circuits or networks got to a peak voltage and then decay after you remove the input signal?

Examples:

An ordinary power supply, made by rectifying AC, then adding a smoothing capacitor. The load is powered entirely by the capacitor during the idle gap between each sine peak.

Dynamic RAM consists of rows of tiny capacitors, each of which represents a 0 or a 1, depending on whether it is charged or discharged. The charged capacitors drop very quickly, and need to be refreshed frequently.

A sample-and-hold circuit, where we want the capacitor to respond quickly when we open a window to the incoming signal, but then we want it to hold the charge long enough before we measure its level.