A lab bench power supply is a circuit designed to help in an engineer in the laboratory whenever the engineer desgins a project he uses the lab bench power supply to test the project

Step 1: Circuit Diagram and Part List of a Lab Bench Power Supply

PART LIST
1):A 220v 50hz transformer.
2):rectifier diode 4pcs
3):filter capacitor 1pcs
4):voltage regulator ic 1pcs
5):switch 1pcs
6):wires
7):indicator led (any color of your choice) resistor10k ohm
8):variable resistor 1pcs.

Step 2: Construction of Circuit.

1)the transformer has a primary and a secondary winding so the secondary winding will be connected to the rectifier diode and coming to the area of the primary winding the color is usually red (not red and black) it is connected to AC on a wall socket.
2)the rectifier diode has a positive and a negative polarity so you connect it normaly to the positive side of the capacitor and that the same with negative side.
3):the voltage regulator ic input pin will be connected to the positive side of the capacitor, the GND to the negative side of the capacitor.
4):the output pin of the regulatory ic will be connected to the switch and from the switch to the positive side of the led with the resistor and from here is the finished circuit. Thanks