Im designing PCB of power supply and im sure of measurement of holes...what sizes can use for Resistors,Capacitors,Variable Resistoer(preset) and Diodes........Plz Help

 

Each device you mention may have differently spaced and sized leads. You can either get the drawing of the components from the manufacturers, look closely in your catalogs to see if that information is there, or use a micrometer to actually measure the lead diameters.

Be sure to leave several thousandths clearance for each component lead.

 

Normally I use holes from 0.6mm to 1.2mm. 0.6mm is for small resistors and small capacitors, 0.8mm for LEDs, big resistors (1W or above, I think) and medium electrolytic capacitors, 1.0mm for TO-220 packages and large capacitors and 1.2mm for large block connectors and large potentiometers.

As beenthere mentioned, you should check the dimensions on the datasheets. Vishay has a lot of them with dimensions for dipped and boxed polyester capacitors, resistors, you name it. Jamicon has a good datasheet for electrolytic capacitors. Both brands specify the lead diameters and spacing for all their products.

 

029, 030, 035 holes in the pads should accommodate most components.

but as beenthere has mentioned, lookup your part via digikey or newark and read the datasheet, it will show lead dimensions.