This universal power supply contains, beside the bridge rectifier, a voltage stabilizer (78xx) and a pnp power transistor. This combination allow a load current up to 5 A. As you know a voltage stabilizer in a TO-220 package can deliver up to 1A. The additional power transistor takes the load current of about 200mA.
The transformer voltage must be greater with 4V than DC stabilized voltage. C1 is calculated for 1A/1000uF, so at 5A C1 must have 4700uF. Both, transistor and voltage stabilizer must be mounted on a heatsink.