Increase Regulator Current
How to Increase Regulator Current IC 78xx
Although the 78xx series of voltage regulators are available with different current outputs, you can increase regulator current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant voltage. Currents up to 650 mA will flow through the regulator, above this value and the power transistor will start to conduct, supplying the extra current to the load.
Increase Regulator Current Circuit of 7805 by TIP2955
Increase Regulator Current Circuit
This should be on an adequate heat sink as it is likely to get rather hot. Suppose you use a 12v regulator, 7812. The input voltage should be a few volts higher to allow for voltage drops. Assume 20 volts. Let’s also assume that the load will draw 5 amps. The power dissipation in the transistor will be Vce * Ic or (20-12)*8=40watt.
It may keep you warm in the Winter, but you will need a large heatsink with good thermal dissipation.
If you want to increase regulator current output with a negative regulator, such as the 79xx series, then the circuit is similar, but an NPN type power transistor is used instead. The 78xx series with PNP – 79xx with NPN transistor type that’s how to increase regulator current.
See also: Universal Laptop Power Supply Circuit – DC DC Converter Circuit.
