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Tuesday, November 16, 2010

5V 5A Higher currents by LM340-5 and 2N4398

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.

5V 5A Higher currents  by LM340-5 and 2N4398
The current that the transistor takes is set by the resistor values R1 and R2, and is I = R2/R1 * RegulatorCurrent. The example shown converts a 1A regulator into a 5A (4A for the transistor plus 1A for the regulator) voltage regulator circuit. See the LM340 datasheet for a full description of this circuit.

High Current Regulated Supply By LM317 and 2N3055×2

transformer to supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and improve efficiency. For good efficiency the voltage at the collectors of the two parallel 2N3055 pass transistors should be close to the output voltage.
High Current Regulated Supply By LM317 and 2N3055×2
The LM317 requires a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10 amps), so a separate transformer and rectifier/filter circuit is used that is a few volts higher than the output voltage. The LM317 will provide over 1 amp of current to drive the bases of the pass transistors and assumming a gain of 10 the combination should deliver 15 amps or more.
By Bill Bowden
Source ::

Stabilized Power Supply With Short Circuit Protection

Here is stabilised power supply with short circuit protection. It’s an efficient 4-stage stabilized power supply unit for testing electronic circuits; and it provides well regulated and stabilized output, which is essential for most electronic circuits to give proper results. The circuit provides an audio- visual indication if there is a short circuit in the PCB under test, so the power supply to the circuit ‘under test’ can be cut-off immediately to save the valuable components from damage.

The circuit provides four different regulated supply outputs (12V, 9V, 6V and 5V) and an unregulated 18V output, which are selectable through rotary switch S2. The selected output is indicated on the analogue voltmeter connected to the outputs rails.

Source: Authorized by D. Mohan Kumar, ELECTRONICS FOR YOU, July 2004