Hello, first post into this forum, I need some help!!
I recently made a project onto a breadbroad, entailing two sections:
An electret mic,
and a (1-bit) simple analog to digital converter.
But it seems a have some load impedance problems causing signal distortion.
The input signal fed into the mic is of low frequency content (fundemantal frequency is below 100Hz)
The electret mic is used as a sensor for impulse-type signals, such ones deriving from percussion applications.
The schematic of the mic is schematic "c" into drumsens.gif..
It is powered from the supply shown into power supply for the electret mic.gif file....
For the A-to-D circuit, I have used a similar circuit to the one shown into "power supply for the electret mic.bpm" file...
...Which has at the beginnig a "full-wave rectifier/absolute value circuit" described into absolute value circuit.pdf file..
For that circuit, R=10...and the o-pamp used is LM741c...
So, doing all that I have experienced the following DIFFICULTIES:
My electret capsule seems to have somekind of built-in preamp, so it appears that when connected to the circuit it is causing signal distortion especially noticable to higher frequencies of the signal,
plus a signal level reduction when I connect all circuits together...
My guess is that everything will be solved with somekind of buffering, but I would like to know the procedure on that one..(perhaps a drawing??)
Last but not least, at the end of the analog to digital converter there is a comparator (LM311) that has to trigger a pulse from "0-to-supply voltage" pulse of variable pulse-width;
according to mic input amplitude level..Which it won't do....
..I am suspecting that it is due to low signal level fed into comparator inputs..could that be the case..??And if so, any suggestion on the solution??
(PS: all circuits are connected on a breadboard and a dual 9V voltage supply )
Many thanks in advance,
best regards,
xmat.
I recently made a project onto a breadbroad, entailing two sections:
An electret mic,
and a (1-bit) simple analog to digital converter.
But it seems a have some load impedance problems causing signal distortion.
The input signal fed into the mic is of low frequency content (fundemantal frequency is below 100Hz)
The electret mic is used as a sensor for impulse-type signals, such ones deriving from percussion applications.
The schematic of the mic is schematic "c" into drumsens.gif..
It is powered from the supply shown into power supply for the electret mic.gif file....
For the A-to-D circuit, I have used a similar circuit to the one shown into "power supply for the electret mic.bpm" file...
...Which has at the beginnig a "full-wave rectifier/absolute value circuit" described into absolute value circuit.pdf file..
For that circuit, R=10...and the o-pamp used is LM741c...
So, doing all that I have experienced the following DIFFICULTIES:
My electret capsule seems to have somekind of built-in preamp, so it appears that when connected to the circuit it is causing signal distortion especially noticable to higher frequencies of the signal,
plus a signal level reduction when I connect all circuits together...
My guess is that everything will be solved with somekind of buffering, but I would like to know the procedure on that one..(perhaps a drawing??)
Last but not least, at the end of the analog to digital converter there is a comparator (LM311) that has to trigger a pulse from "0-to-supply voltage" pulse of variable pulse-width;
according to mic input amplitude level..Which it won't do....
..I am suspecting that it is due to low signal level fed into comparator inputs..could that be the case..??And if so, any suggestion on the solution??
(PS: all circuits are connected on a breadboard and a dual 9V voltage supply )
Many thanks in advance,
best regards,
xmat.