need help pls! :(

my team are doing on tactile auditory sensory substution (a hearing aid for high frequency hearing disablities) and we are completey noob in engineering and the project is due in 4 weeks time, so we really need some help and guidance. We so far set-up the band-pass filters, and we are now doing the comparators so we can activate the filters once vref has been set for each. Thing is what we need help is:

- how to set the vref according to the voltage of the circuit
- how to set the threshold
- how to set the voltage divider? variable resistor? or two resistors? if resistor, how do we calculate?
- does LM386 amplifies external signal?
- will an LM741 used as an audio amplifier?
- and we are not sure why our filter is not consistent in giving the output signal.

Thats all we need to know, and trust me i did the research on wikipedia, ourserve.com everything.. and we do not have textbooks, cause we doing PBL, thats why we are suffering. pls help! pls pls..all we need is tips and guidance of basic analog circuits

You forgot to post your schematic so we don't know what is connected wrong.
"We doing PBL". What is PBL?

Problem based learning. anyways here is the schematic for our filter design. how do you add the comparator and voltage divider so that the filter can be triggered separately?

You saved your schematic as a very fuzzy JPEG file type instead of a very clear GIF or PNG file type. Can't you turn off the dots?

Your opamps are overloaded by the 1k resistors to ground on their outputs.

The outputs of the bandpass filters is AC but comparators work with DC.

audioguru said:

Your opamps are overloaded by the 1k resistors to ground on their outputs.

Click to expand...

The new eyes are working well AG! - the picture was so small and blurred I couldn't tell what value they were.

Hi Nigel,
I wish people would stop posting fuzzy JPEG schematics that have measles dots all over them.

My fixed eyes are extremely clear and colours are amazing now.