high current pulse from small voltage regulator --- just need large capacitor?

[NuNDoe]

i need to pulse 3A's out of a standard LM7805 regulator (SOT223 package) ---- but the regulator is rated for at most 1A... can I achieve this high amperage pulse simply with a large enough output capacitor? the pulse is worst case 25% duty cycle --- which means the average current is under 1A. Does that seem reasonable? anything I'm overlooking?

Thanks!

 

[FvM]

You can calculate the capacitance based on the intended pulse duration and acceptable voltage drop. Do you get at reasonable value?