How would I go about changing the frequency output given out by an op amp? I've looked into 555 timers and also schmitt Trigger Oscillators. I have an AD8232 op amp and I'm wanting to change the output frequency to around 20 khz. When I plug it into a speaker it is rather low, I'm lost on if I need to use a 555 timer or use a piezo electric speaker rated at that frequency or both and how would a schematic look.
Regards
Regards