Friday, January 24, 2020

5 in 1 transformer-based Adjustable Bench Power Supply

In this post, I will show you how to make transformer-based power supply which
has built-in functions like Connectivity Tester, IR or Remote tester &
LED Tester


The main part which is the bench power supply is built with the IC LM317 adjustable
voltage regulator. LM317 provides an output voltage of 1.2v to 37v depending on the
input supplied. For example, if you supply 24v as the input you will only be able to get an
output around 21v. In the circuit Diode D5 & D6 protects from short circuit.
Diode D1, D2, D3 & D4 are arranged in a bridge rectifier configuration.
Capacitor C1 & C2 is used as a smoothing capacitor.
For connectivity & LED testing circuit BC548 transistor is used. And for the
IR or Remote testing LM358 is used.


     You can also watch the video for all the details on how to make this project

Things & Components you need

  • 1 * LM317 with Heat Sink
  • 1 * LM358
  • 6 * 1N4007
  • 1 * IR Rx
  • 1 * Pot Knob
  • 1 * Buzzer
  • 1 * 8 Pin Socket
  • 5 * 2 Pin Terminal Block
  • 1 * 3 Pin Terminal Block
  • 1 * Voltmeter with Ammeter
  • 2 Pair * Banana Connector male & female
  • 1 * LED
  • 1 * BC548
  • 1 * AC Cable
  • 1 * 10K Trimmer
  • Ceramic - 0.1uF
  • 1 * 2 Way Switch
  • 1 * 4.7K Pot with Knob
  • Resistor - 2 * 120, 330, 470, 10K
  • Electrolytic Cap - 10uF/50v , 470uF/50v
  • 1 * 220v to 0-24v 1Amp Transformer

Affiliate Links

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Making & Assembly

Using the circuit diagram which is shared create the PCB Layout & generate
the Gerber files for Fabrication.

Once the Gerber file is generated upload the same on the fabricator website.
My fabricator being JLCPCB. The board provided by the JLCPCB was very good.
I recommend JLCPCB for fabrication. Note: You can download the Gerber files for
ordering your own PCB board at the download section. Also, note the Gerber file is
created using KiCAD.

After receiving the board mount all the components according to the circuit
diagram & part number.

After completing the board, make holes in a container for mounting all the external
components & connectors and also the PCB board & transformer.

After making holes mount all the components, PCB board & the connectors
and then make all the required connection between the PCB board & the
external components & connectors. For the connections, you can refer to the
block diagram.

Once everything is mounted name the connectors accordingly.

Now for using the bench power supply, power the circuit with 220v AC & use
the knob to adjust the voltage as per your requirement.

For connectivity test, First set the voltage to around 5 to 9V, then connect two wires
 in the Connectivity section & use the switch to select the connectivity &
then check for the connectivity in any circuit.

For testing the IR or remote, First set the voltage to around 5 to 9V, then face the
remote towards IR Rx and press any button, as the button is pressed the LED will
start blinking. At first, if you have a problem getting LED to blink try adjusting the
10K trimmer while pressing the button in the remote until you get a blink.

For LED Testing use the same setting as the connectivity testing.

Circuit Diagram

Block Diagram

Thank you for reading !!!

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