Analog Filter circuit for Brain wave recognition system

[wcsperera]

Hi everyone ................

I want to do a project to recognise brain waves(alpha, beta...etc) respectively using brain wave sensor. so I need to design filter circuit to filter the noises like power line noise, 50Hz.


** I need to know what kind of filter circuit is suitable for this(Low pass/ band pass) and the order of the filter and other relevent features should be in filter for my project.

** And if can please let me know suitable web-sites to get the information/ guide lines regarding this project. (It is more useful to know contact of person who did this kind of project)


I hope kind reply soon............

 

[LvW]

Hi everyone ................
I want to do a project to recognise brain waves(alpha, beta...etc) respectively using brain wave sensor. so I need to design filter circuit to filter the noises like power line noise, 50Hz.

** I need to know what kind of filter circuit is suitable for this(Low pass/ band pass) and the order of the filter and other relevent features should be in filter for my project.
.............

I am afraid, we cannot help you as long as you do not provide us with some more information.
You need a "filter" circuit ? And you ask "what kind of filter is suitable" ?
This only depends on YOUR requirements which we do not know:
Which frequencies have to pass the filter and which frequencies have to be attenuated - and by how many db?

 

[flatulent]

A low pass filter will fit your needs. Since this is subaudio frequencies I suggest an active filter.

Several IC companies have simple design programs that can be downloaded.

 

[LvW]

A low pass filter will fit your needs. Since this is subaudio frequencies I suggest an active filter.

Several IC companies have simple design programs that can be downloaded.

Yes, that´s true. But - one should not expext too much from such a program.

These programs cannot overtake the first steps of the design process.
1.) To formulate and fix the requirements
2.) To select an appropriate low pass approximation - in conjunction with the required order and a suitable filter structure (out of 10-20 theoretical alternatives).
3.) The program makes some suggestions/proposals - but the choice is up to the user!
4.) And one should not overlook that - in most cases - the most powerful structures (like GIC, leapfrog, FDNR) are NOT covered by the programs.
5.) Last point: Selection of an appropriate filter topology is very critical especially for subaudio frequencies, because of the large time constants and the associated bad quality of the components (capacitive and resistive parasitics).