This is the regulated current booster designed to increase the DC current of a power supply.
Even though the 78xx series of voltage regulators are readily available with diverse current outputs, you could increase the obtainable current output with this circuit. A power transistor is utilized to provide additional current for the load the regulator, preserving a continuous voltage. Currents as much as 650mA will flow by way of the regulator, above this value along with the power transistor will start out to conduct, supplying the additional existing for the load. This needs to be on an sufficient heat sink as it is actually most likely to obtain rather hot. Suppose you use a 12V regulator, LM7812. The input voltage must be a number of volts greater to permit for voltage drops. Assume 20 Volts. Lets also assume that the load will draw 5 amps. The power dissipation within the transistor will likely be Vce * Ic or (20-12)*8 = 40 Watt. It may possibly preserve you warm within the Winter, but you might have to have a big heatsink with very good thermal dissipation.
If you would like to enhance the output current using a negative regulator, just like the 79xx series, then the circuit is comparable, but an NPN type power transistor is applied as a substitute.