The 0.28-inch Mini Digital Voltmeter is an ultra-compact, high-precision measurement tool designed for real-time voltage monitoring. At Electrapac, we recommend this 3-wire module for DIY power supplies, battery chargers, and electronic test benches where space is limited but accuracy is essential.

Product Overview

This digital voltmeter features a bright, 3-digit LED display and is capable of measuring a wide range from 0V to 100V DC. The 3-wire configuration is its most powerful feature: it allows the meter to be powered by a separate stable source (like a 5V rail) while measuring a completely different voltage source, even down to 0.00V.

Key Features for Electrapac Customers

• 3-Wire Versatility: By separating the "power" wire from the "measurement" wire, you can measure voltages close to zero. (Standard 2-wire meters usually die below 4V).

• High Visibility: Despite its tiny 0.28" size, the high-intensity LED display is easily readable from several feet away.

• Calibration Potentiometer: Located on the back of the PCB is a tiny trim-pot, allowing you to fine-tune the accuracy against your professional multimeter.

• Reverse Polarity Protection: Integrated safety circuitry prevents the module from burning out if the power wires are connected backward.

• Auto-Scaling Decimal: The decimal point moves automatically to provide maximum resolution (9.99V vs 99.9V).

Wiring & Connection Guide

To integrate this into your Electrapac project, follow the standard 3-wire color code:

1. Red (VCC): Power supply for the meter itself (+4V to +30V DC).

2. Black (GND): Common Ground (connect to both the power source and the measured source).

3. White or Yellow (VIN): The measurement probe. Connect to the voltage you want to measure (0V to 100V).

Electrapac Tech Tip: If you are measuring the same battery that is powering the meter (and the voltage is between 4V and 30V), you can simply twist the Red and White/Yellow wires together and connect them to the battery positive.

Primary Applications

• Variable Power Supplies: Adding a permanent voltage readout to your custom-built lab bench power supply.

• Solar Systems: Monitoring the charge level of 12V, 24V or 48V battery banks.

• RC Vehicles: Monitoring Li-Po battery voltage in drones or RC cars to prevent over-discharge.

• Electric Scooters: A compact "gas gauge" for electric bikes and scooters.

• Industrial Panels: Real-time voltage status for control cabinets and automated machinery.

Why Shop at Electrapac?

We source our Mini Voltmeter Modules with high-quality LED segments that won't flicker over time. Visit us at for the precision monitoring tools that keep your power systems in check.