I am trying to build a simple pulse generator circuit for electrophysiological stimulation purposes. It seems to be surprisingly difficult to generate a square/ pulse waveform where the pulses have precise amplitudes.
To generate pulses I have tried audio output from my computer, the digital outs from an Arduino, and a 555 monostable, and when recorded they all turn out with a bad case of the jitters (randomly varying amplitude).
Below are recordings taken straight from audio out of my computer into acquisition box. I have also tried using alternative generators such as an Arduino and a 555 and got the same jitter on everything.
My primary questions are what is causing this jitter, what am I doing wrong and how do I fix it? I need precise amplitude control. I have tried different recording devices and they show the same thing. 2) How can I get rid of overshoot? I have tried diodes for this and not had much luck.