Extended core controller access

Hello everyone,

I am new to codeigniter and so far i am really excited about it. I have run into some problems and i need some help..

I have created a custom core controller in the folder application/core which i would like to use for system wide variables and methods in my application. I did this by following the guide Creating Core System Classes

Here is my code:

class OBJ_System extends CI_Controller {
 
 public function __construct() {
  parent::__construct();
  ....
 }
 
 public function index(){
  //....
 }
 
 public function do_something() {
    .....
  echo "i did it";
 }
}

whenever i try from one of my view to post something to the method do_something() of my core controller

$.post( "OBJ_System/do_something/", {"params": 'do_this'},  function( data ) {
 });

i get the following

404 Page Not Found The page you requested was not found.

can anyone help me with this? How can i post data to my core controller?

ps. I have tried a different approach. I created a controller called System, withing my application/controllers folder. Whenever i post something to this controller

$.post( "system/do_something/", {"params": 'do_this'},  function( data ) {
 });

i get a 403 Forbidden response.. this happens because of the .htaccess file in the system folder. How would you solve this issue?

Thank you in advance..!!!