Project Hub /Test & Measurement Instrumentation/Multimeters, Voltmeters & Ammeters/Power Supply With Digital Volt-Amp Panel Meter

Intermediate

ANALOG / DISCRETE

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Power Supply With Digital Volt-Amp Panel Meter

A variable DC power supply featuring an LM317 adjustable voltage regulator and a built-in digital volt-amp panel meter for real-time voltage and current monitoring.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: Voltage Regulator IC (7805 / LM317 / 1117)
Transformer
Diodes (1N4007 / 1N4148 / Schottky / Zener)
Capacitors
Potentiometer / Trimpot
Custom PCB / PCB Fab
Digital panel meter

Browse all components

How It Works

This variable DC power supply project converts high-voltage alternating current into a stable, adjustable direct current output monitored in real time. The circuit begins with a 230V AC primary to 15V 1A secondary transformer (X1), which steps down the high mains voltage to a safer AC level. This stepped-down AC is then fed into a bridge rectifier formed by diodes D1 through D4, converting the alternating current into pulsating DC. Capacitor C1 smooths this pulsating DC into a raw DC voltage bus. The core regulation is handled by the LM317 adjustable voltage regulator (IC1). By adjusting the 22-kilo-ohm variable resistor (VR1) in conjunction with the 680-ohm resistor (R2) connected to its adjustment pin, the output voltage can be precisely controlled across a continuous range. Additional capacitors C2 and C3 improve transient response and output stability. Diode D5 provides reverse-bias protection for the regulator. The output feeds a connected load while simultaneously powering a digital panel meter (DPM1), which provides real-time readouts of both the delivered voltage and current. Finally, LED1 serves as a visual indicator to show when the power supply is active.

Why Build This

Provides an adjustable, regulated DC benchtop power source essential for powering and testing undergraduate-level electronics prototypes and laboratory experiments.

Integrates real-time voltage and current monitoring via a digital panel meter, allowing engineering students to observe load characteristics dynamically.

Offers practical hands-on experience with linear voltage regulation principles, mains-frequency step-down transformation, and rectification.

Real-World Application

Benchtop testing, laboratory experiments, electronics prototyping, and powering various DC electronic circuits requiring adjustable voltage and current monitoring.

Skills You'll Learn

Mains voltage step-down transformation

AC-to-DC bridge rectification

linear voltage regulation design

resistive voltage adjustment

digital panel meter integration

Safety Precautions

Exercise caution when working with 230V AC mains input. Ensure all connections are secure before powering on, and use a suitable heat-sink for the LM317 regulator to prevent overheating.

Technology Tags

LM317

VOLTAGE REGULATOR

BRIDGE RECTIFIER

DIGITAL PANEL METER

PCB DESIGN

BREADBOARD

Frequently Asked Questions

Why is a heat-sink necessary for the LM317 regulator?

The LM317 drops the excess voltage across itself as heat, especially when there is a large difference between the input voltage and a low output voltage, requiring thermal management to prevent overheating.

Can the digital panel meter measure any load current?

The panel meter monitors the current drawn by the load, but the entire power supply is limited by the 1A secondary rating of the transformer (X1).

What is the purpose of diodes D1 through D4?

Diodes D1 through D4 form a bridge rectifier that converts the incoming AC voltage from the transformer secondary into pulsating DC voltage.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

PRJ-00649