Project Hub /Test & Measurement Instrumentation/Multimeters, Voltmeters & Ammeters/Milliamp Meter For 1mA To 100mA

Beginner

ARDUINO

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Milliamp Meter For 1mA To 100mA

A precise low-current milliamp meter circuit built around an Arduino Uno and a 16x2 LCD display to accurately measure currents ranging from 1mA to 100mA.

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.

Arduino UNO R3 Board (Compatible) – ATmega328P Microcontroller with USB Cable Rs. 999.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
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: LCD (generic / unspecified)
Magnets / Electrodes / Probes
9V Battery + Snap

Browse all components

How It Works

The Milliamp Meter For 1mA To 100mA project functions by routing the current of the circuit under test through a precision sense resistor, designated as R1, which features a tolerance within 2% and a minimum wattage rating of 0.5W. As current flows through this sense resistor, Ohm's law dictates that a proportional voltage drop develops across it. The Arduino Uno's analog input pin, specifically pin A0, measures this small voltage drop. Inside the Arduino Uno board, the microcontroller's analog-to-digital converter (ADC) samples the analog voltage and converts it into a digital value. Using the source code provided in 'mA_meter.ino' compiled via the Arduino IDE, the microcontroller applies the appropriate mathematical scaling factors based on the known value of R1 to calculate the exact current in milliamps. Once computed, the current value is dynamically updated and rendered visually on a 16x2 LCD display, allowing the user to easily read real-time low-current measurements. The entire system is powered by a stable 9V battery or a 9V 500mA adapter, supplying the necessary operating voltage to both the Arduino board and the attached display.

Why Build This

Design and characterize custom low-power embedded system circuits that require high-resolution current monitoring beyond standard digital multimeters.

Apply fundamental circuit theorems like Ohm's law in a practical instrumentation context using precision passive components.

Develop integrated hardware-software measurement tools using an Arduino Uno and custom C++ source code.

Real-World Application

Useful for testing and debugging low-power DIY electronics projects, hobbyist circuits, and embedded systems where standard multimeters lack sufficient resolution for low-current measurement.

Skills You'll Learn

Analog-to-digital conversion

Voltage drop measurement

Precision resistor selection

LCD display interfacing

Basic instrumentation circuit design

Safety Precautions

Do not reverse the polarity of the cable as it may destroy the Arduino board. Ensure current at analog pin A0 does not exceed 100mA.

Technology Tags

ARDUINO

ADC

MICROCONTROLLER

LCD DISPLAY

CURRENT MEASUREMENT

ANALOG-TO-DIGITAL CONVERSION

Frequently Asked Questions

Why must resistor R1 have a minimum wattage of 0.5W?

A 0.5W rating ensures the resistor can safely dissipate the heat generated by maximum current flow without overheating or changing its resistance value.

Can I power this meter using a standard USB cable instead of a 9V battery?

Yes, powering the Arduino Uno via USB provides the necessary regulated operating voltage while simultaneously allowing you to upload the 'mA_meter.ino' source code.

Why does the meter only measure up to 100mA?

The circuit is specifically scaled and bounded for low-current applications to maximize resolution within the 1mA to 100mA range; exceeding 100mA can stress the analog pin and sense resistor.

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.

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