hellow dears
i made a power supply (0-15v) and now i want its digital output which is voltmeter with digital output ,
give me some idea how i make such voltmeter and how i attach this with power supply.

 

Here is a link to a project - http://electronics-diy.com/ICL7107_volt_meter.php

Use the resistor change that scales the output to 19.99 volts for your power supply voltage.

 

thanks
please tell me the purpose of using ic 7660, why we use this .

 

the 7660 IC is used as a voltage inverter to create the -5v supply from the +5v supply.
If you have +5v and -5v available already, you do not need the 7660 IC.