Switching AC to DC converter for LEDs (no resistor)

[mohsen_sam]

i need a schematic for convert 220v Ac to 40v dc with dont use resistor,and
only use diod and capacitor(switching power suplly use buck converter) ,please help me Immediately,please!

 

[mohsen_sam]

this circuit use in led light lamp :
**broken link removed**

 

[dknguyen]

SO you need an AC-DC power supply that is current regulated so it can power an LED without using a current limiting resistor? Is that what you mean by no resistor?

 

[mohsen_sam]

SO you need an AC-DC power supply that is current regulated so it can power an LED without using a current limiting resistor? Is that what you mean by no resistor?

for example buck converter dont need any resistor,
so losses reduce in This type of circuites,
i want to use Bridge Rectifiers with buck converter to
reduce voltage to almost 40 volt dc,but i dont have any safe
diagram for this.
what kind of connection between elements do i need?