How to Build an LM723 Pass Transistor

The LM723 pass transistor circuit is a specialized circuit that is sometimes added to the LM723 voltage regulator for it to increase output current. A voltage regulator is a device that automatically maintains a constant voltage level and may be used to regulate one or more alternating current or direct current voltages. The LM723 voltage regulator supplies output currents up to 150 milliamps. However, extra external transistors can be added to boost output.

Things You'll Need

• Phillips screwdriver
• 2 2N3055 pass transistors

Instructions

1. Disconnect the voltage regulator from its power supply by unplugging it.

2. Remove the outer casing of the power supply with a Phillips screwdriver.

3. Insert one 2N3055 pass transistor on the circuit board at the output plug of the voltage regulator. Insert the ends of the transistor into the circuit board. Insert the other pass transistor at the input plug and connect its terminals to the circuit board.

4. Plug in the soldering iron and the use it to melt a small amount of solder to each contact of both transistors.

5. Place the voltage regulator case back on and replace the retaining screws with the screwdriver. Plug the voltage regulator back in.

References

• LM723 3-Terminal Voltage Regulator Owner's Manual; National Semiconducter