Hi
I want to design constant current source of 10mA. My load will vary from 10 ohms to 5K ohms. I tried using current mirror circuit, but i am unable to achieve 10mA. Current mirror gives only 2mA constant current. Please suggest me another circuit which gives me 10mA constant current source. I have tried another circuit using op-Amp but it gives the constant current of 10mA up to 1.4k load range.

when i tried to increase current capacity then it fails to reflect the current at output side.

No i haven't tried that...I have no idea about it. Please let me know how to  do this.

Thanks

What are your supplies?
10 to 5k seems too large of variations(0.1V to 50V?)