If you want circuit to use a higher current regulator - up to 5A regulators are available. Please see here circuit,it good idea very much.
In this circuit, the transistor Q1 is used to share some of the current supplied. The voltage regulator maintains the output voltage, and still operates short circuit protection. The current [...]

Although semiconductor diodes available today are close to ideal” devices, they have severe limitations in low level applications. Silicon diodes have a 0.6V threshold which must be overcome before appreciable conduction occurs. By placing the diode in the feedback loop of an operational amplifier, the threshold voltage is divided by the open loop gain of [...]

This is circuit Dual Voltage Power Supply 1A +12V and -12V, Useful IC Regulator hot IC 7812 and 7912.
Please see circuit in Source web : Link
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