Can you give a circuit that would clean up noisy audio signal?
Basically, I have created a square wave from a software (Real Time Analyzer) at certain frequency to the audio jack port of the computer.
The output of the oscilloscope yields the signal as shown on the top part of the image above. The signal I created from the software is similar to the bottom part of the image. There is no problem with the software. My problem is how to clean the noisy signal from the audio jack? That is, how to make the output from the circuit created similar to the bottom part of the image?
I want to have a circuit that would clean the signal.
Best Answer
The simplest way would be to simply feed it through any logic IC which features Schmitt Triggering.
A Schmitt trigger has what is called input hysteresis.
This includes many of the 7400 series of logic ICs. There is a list Here, just Ctrl+F for "schmitt".
Alternatively, if you really want to do it yourself, it's pretty simple to achieve with an Op-Amp.
The way this circuit works is fairly simple.
All together, this is called positive feedback (as you can see, the output is connected to the positive input. As a result, the transition threshold is affected by both the output state and the input state
The term for this, e.g. the output as both a function of the input and the previous output is Hysteresis.
When hysteresis is implemented in a circuit like this, it is called input hysteresis.