FNIRSI LCR-ST2 LCR Meter & ESR Tester — Digital Tweezer

FNIRSI LCR-ST2 LCR Meter & ESR Tester — SMD Tweezer

The FNIRSI LCR-ST2 is a handheld LCR meter and ESR tester built around a tweezer form factor, designed for UK engineers and hobbyists who need to measure SMD components in-circuit or from a reel. It measures resistance (10mΩ–10MΩ), capacitance (1pF–22mF), inductance (1μH–10H), diode forward voltage, and DC voltage up to ±30V. Five selectable test frequencies from 100Hz to 100kHz and four RMS excitation levels let you characterise components accurately across the full audio and low-RF range.

• Measures R, C, L, diode & voltage — resistance 10mΩ–10MΩ, capacitance 1pF–22mF, inductance 1μH–10H
• 5 test frequencies — 100Hz, 120Hz, 1kHz, 10kHz, 100kHz for precise characterisation
• D/Q/Z/X/θ/ESR readouts — full parametric profile, not just the primary value
• Full-band sweep (100Hz–100kHz) — frequency response of any component in a single action
• Intelligent OK/NG sorting — set a nominal value and tolerance, batch-test components automatically
• Tweezer tips + Kelvin clip (Plus) — probe SMD pads and through-hole leads without adapters
• Auto R/C/L recognition — identifies component type on contact, no manual mode switching
• 300mAh battery, ~3 hours — Type-C charged, 1.47″ HD colour display, 60.8g

What components can the LCR-ST2 measure?

The LCR-ST2 measures resistors, capacitors, and inductors across wide ranges — 10mΩ to 10MΩ, 1pF to 22mF, and 1μH to 10H respectively. It also tests diodes (forward voltage up to 0.7V) and measures DC voltage up to ±30V. Secondary parameters D (dissipation factor), Q (quality factor), Z (impedance), X (reactance), θ (phase angle), and ESR (equivalent series resistance) are displayed alongside the primary measurement for a complete component profile.

Why does test frequency matter for LCR measurements?

Capacitors and inductors behave differently at different frequencies — an electrolytic capacitor measured at 100Hz and at 10kHz will show different capacitance and ESR values. The LCR-ST2’s five selectable frequencies (100Hz, 120Hz, 1kHz, 10kHz, 100kHz) let you test at the frequency closest to the component’s operating point. The full-band sweep runs all five frequencies in a single action, plotting how impedance, ESR, and phase angle change across the 100Hz–100kHz range — useful for characterising filter components, ferrite beads, and power inductors.

What is the difference between LCR-ST2 Plus and Standard?

The Plus adds a Kelvin clip accessory to the standard tweezer tips. Kelvin clips provide four-wire (Kelvin) measurement — separate current and voltage connections — which eliminates lead resistance from the reading. This matters for low-resistance measurements (below ~1Ω) and for testing through-hole components and larger axial capacitors that the tweezer tips can’t grip cleanly. The Standard suits most SMD reel-testing and in-circuit work. For through-hole and low-ohm precision work, the Plus is the correct choice. For a simpler single-frequency tweezer tester, the FNIRSI LCR-ST1 covers basic R/C/L on SMD at lower cost.

How does intelligent sorting work?

Set a nominal value (e.g. 100nF) and a tolerance (e.g. ±5%), and the LCR-ST2 evaluates each component against those limits, displaying OK or NG on-screen. Touch a component with the tweezers and you get a pass/fail result in under a second. This is the practical way to bin components from an unmarked reel, verify capacitor values before fitting, or sort a bag of mixed inductors by value — without manually reading each measurement against a target.

Is the LCR-ST2 better than a multimeter for component testing?

For capacitance, inductance, and ESR — yes, significantly. A typical multimeter measures capacitance at a single low frequency and shows no inductance or ESR at all. The LCR-ST2 tests at five frequencies, shows ESR (critical for electrolytic capacitor health testing), displays D/Q/Z parameters, and auto-recognises component type. For basic resistance and voltage, a multimeter is sufficient. For anything involving reactive components, the LCR-ST2 gives a complete picture a multimeter cannot. For a full bench LCR bridge with higher accuracy and wider range, the FNIRSI LC1020E digital bridge steps up further.

Best for

SMD component verification from reel, electrolytic capacitor ESR testing, inductance and ferrite bead characterisation, filter component frequency-response sweeps, batch OK/NG sorting before PCB assembly, in-circuit passive measurement, power supply ripple component inspection, audio crossover component matching, RF coil and transformer testing, and prototype PCB debugging where a quick component check replaces desoldering and bench testing. For through-hole component testing across transistors and diodes, the FNIRSI LCR-P1 component tester handles transistors, MOSFETs, and Zener diodes.

What’s In The Box

• FNIRSI LCR-ST2 tweezer
• Kelvin clip (Plus option)
• Curved tip
• Shorting plate (for zero calibration)
• Storage bag
• USB-C data and charging cable

Why Kunkune

Shipped from our Oxfordshire warehouse via Royal Mail 1–2 day delivery. 12-month warranty on all FNIRSI products. 60-day returns. No drama.

Frequently Asked Questions — FNIRSI LCR-ST2

Can the LCR-ST2 test capacitors in-circuit?

Yes, with caution. In-circuit measurements are approximate because parallel components affect the reading. Power down the circuit and discharge capacitors before measuring. For accurate readings, desolder one leg of the component or test from a reel before fitting.

What does ESR tell me about a capacitor?

ESR (equivalent series resistance) is the best indicator of electrolytic capacitor health. A new capacitor might measure 0.05–0.2Ω; a failing one can measure several ohms. High ESR causes power supply ripple, instability, and heat in switching circuits — checking ESR is more useful than checking capacitance alone for fault-finding.

What is the shorting plate for?

The shorting plate lets you zero-calibrate the LCR-ST2 before measuring — short the tweezer tips onto the plate, run the open/short calibration routine, and the meter nulls out lead resistance and stray capacitance. Always calibrate before precision measurements at 10kHz or 100kHz.

Does the LCR-ST2 measure transistors or MOSFETs?

No — the LCR-ST2 measures passive components (R, C, L) and diode forward voltage. For transistor, MOSFET, Zener, and thyristor testing, the FNIRSI LCR-P1 is the right tool.

Can I export measurements to a PC?

The USB-C port supports data export via the FNIRSI PC software. This allows logging of sweep measurements and batch sorting results to a spreadsheet — useful for component characterisation reports and production QC records.

How do I set the auto-rotate for left-handed use?

Hold the power button during startup to toggle screen orientation. The hand-sensing auto-rotate adjusts the display when you switch hands, keeping measurements readable without reaching for a menu setting.