Current Expanded Regulated Power Supply

Actually, this is ordinary regulated power supply, but the current expander using a transistor make this power supply become powerful.

Based on the datasheet, the stabilizer IC’s can deliver up to 1A output current. For example 78xx series regulators are available in different voltage ratings, but in any case the current should not exceed 1A.

The transistor Q1 (2N 29055) used here has 5A current capacity. The resistor R1 is used to keep the current through regulator IC below 300mA. When the current through R1 increases the base current of Q1 (2N 29055) also increases & the load required load current flows through this transistor. By this way a current greater than the capacity of the regulator IC can be delivered to the load. The C1 is used to filter the ripples off the rectifier output.

Download this schematic diagram.

Notes:

1. Assemble the circuit on good quality PCB.
2. T1 can be a 230V primary,15V/1A secondary, step down transformer.
3. If 1 A bridge is not available, make one using four 1N 4007 diodes.
4. The series regulator IC should be selected according to the desired output voltage.

• IC 7805 for 05V
• IC 7806 for 06V
• IC 7809 for 09V
• IC 7812 for 12V

Semiconductor datasheet download. (PDF Format)

1. LM78XX
2. 2N2955