ya, i am using a single polarity supply, because i think that if using +-5v, a 9V battery may not enough power to supply it. since the hearing aid should be portable and small,then i cant use a power supply for source instead of battery.Is that mean that it must use AC power instead of single polarity?If your circuit is powered from +-5V then 0V is at "half the supply voltage". The output can swing equally up and down to make the undistorted AC signal.
You show a 'scope waveform that is rectified (extremely distorted) because your circuit is biased at 0V with a single polarity supply then it cannot produce the missing negative part of the waveform. It should be biased at half the supply voltage for the output to swing equally up and down.
I do have a highpass filter before , but due to the waveform of output is rectified,so i decide to cancel it. the oscilloscope waveform that i show you just now is take from the highpass filter that attach below.You don't have a highpass filter circuit. Your lowpass filter was biased wrong at 0V.
For my lowpass filter, it wont biased wrong at 0V when i set an offset for my input. This problem just happen when i using high pass filter.
Ps: do you know that a EM noise that genereated by mobile phone can or can not be filter off by filter?i think that EM noise is one type of radio frequency with high frequency( probably few MHz?)
Thanks!
Attachments
-
78.6 KB Views: 25