FNIRSI DMT-99 Digital Multimeter 9999 Counts TRMS - Recording

Our review of the FNIRSI DMT-99 finds it best suited to electronics hobbyists and technicians who need a compact, accurate meter with modern convenience. The single biggest reason to buy is the combination of 9999 counts TRMS accuracy and practical recording and monitoring modes that let users capture changing voltages or currents over time, making diagnosing intermittent faults much easier than with a basic multimeter.

Key Features

• Recording Mode: The meter can plot measured value ripple over time and store up to eight recorded readings so you can view fluctuations and Max/Min values after a test.
• Monitoring Mode: Custom thresholds can be set and the meter issues an alert if readings go outside the defined range, helping catch transient problems.
• Rechargeable Battery: Built-in 1500 mAh battery and Type-C charging eliminate disposable batteries and provide long runtime for field use.
• Intelligent Auto-Ranging: Intelligent mode automatically identifies the measurement type and selects the optimal range for faster, no-guess testing.
• Color Display: A 2.4-in full-color TFT screen at 240x320 resolution makes readings clear in dim light and supports a customizable startup interface.
• Wide Function Set: The DMT-99 measures AC/DC voltage and current, resistance, capacitance, continuity, diode checks, frequency, NCV and live wire detection, useful across repairs and troubleshooting.

Who It's For

The DMT-99 is aimed at electronics hobbyists, appliance and automotive DIYers, and technicians who value accurate TRMS readings and the ability to record or monitor signals over time. Its rechargeable battery and USB-C charging make it practical for frequent use away from a bench.

Users who only need occasional, very basic voltage checks or prefer the simplest single-function meters may find the feature set more than required; likewise, those needing laboratory-grade instrumentation with calibrated traceability should look to specialized test equipment instead.

Pros & Cons

Pros

• High-resolution 9999 counts TRMS measurement improves accuracy for non-sinusoidal signals.
• Recording and monitoring modes help identify intermittent issues that a static reading would miss.
• Long-lasting built-in 1500 mAh battery and convenient Type-C charging remove the need for disposable batteries.
• Clear 2.4-in color display with DIY startup interface for personalized use.

Cons

• Not a substitute for calibrated lab instruments where formal certification and traceability are required.
• Advanced functions add complexity that may be unnecessary for users wanting a very simple meter.

Specifications

Counts	9999 (TRMS)
Display	2.4-in full-color TFT, 240x320
Battery	Built-in 1500 mAh rechargeable, Type-C charging
Measurement Modes	AC/DC voltage, AC/DC current, resistance, capacitance, diode, continuity, frequency, NCV
Recording	8 measured values, Max/Min display, plotted ripple
Protection	Dual ceramic fuse protection

Our Verdict

The FNIRSI DMT-99 is a strong value for hobbyists and field technicians who need accurate TRMS readings plus recording and monitoring features in a rechargeable package. It pairs practical runtime and USB-C charging with a clear color display, making it a versatile tool for troubleshooting intermittent electrical problems without the cost or complexity of lab equipment.

Frequently Asked Questions

Does the meter recharge via USB-C?
Yes, it has a built-in 1500 mAh rechargeable battery and recharges using the Type-C port.

Can it record changing voltages over time?
Yes, the Recording Mode plots ripple and fluctuation over time and stores up to eight measured values with Max and Min shown.

Is this meter suitable for professional lab calibration?
It provides accurate TRMS readings for field and workshop use, but it is not intended as a certified calibrated lab instrument with traceable calibration documents.