Alphalab GM1-ST DC Gaussmeter
| Brand | Alphalab |
|---|---|
| Origin | USA |
| Model | GM1-ST |
| Measurement Range | 0 to 19,999.9 G |
| Resolution | 0.1 G |
| Display | 5½-digit LCD |
| Update Rate | 4 readings/sec |
| Sensor Cable Length | 100 cm (flexible, bendable tip) |
| Minimum Gap Clearance | 0.060 in (1.5 mm) |
| Operating Principle | Hall-effect DC magnetic field sensing |
Overview
The Alphalab GM1-ST DC Gaussmeter is a precision handheld instrument engineered for reliable, high-resolution measurement of static (DC) magnetic fields. Utilizing a calibrated Hall-effect sensor, the GM1-ST delivers direct, linear response to magnetic flux density in gauss (G) units without requiring zeroing or calibration before each use. Its fixed-range 5½-digit display eliminates range-switching latency and ambiguity—offering unambiguous resolution down to 0.1 G across its full 0–19,999.9 G span. Designed for rapid deployment in production, quality assurance, R&D, and magnet characterization environments, the GM1-ST operates instantly upon power-on with no warm-up time or configuration required. The unit conforms to fundamental metrological principles for DC field measurement, supporting traceable verification against NIST-traceable standards when used with documented sensor calibration certificates.
Key Features
- True 5½-digit LCD display (200,000-count resolution) — eliminates manual range selection and reduces operator error
- Hall-effect sensor with integrated temperature compensation for stable DC field readings across ambient conditions (15–35 °C)
- Ultra-thin, flexible sensor tip (1.5 mm thickness) enabling insertion into narrow air gaps as small as 0.060 in (1.5 mm)
- 100 cm low-noise coaxial cable with strain-relieved, bendable sensor housing — allows L-shaped configuration for bore or gap measurements
- Fixed full-scale range: 0–19,999.9 G — optimized for repeatability and linearity without auto-ranging artifacts
- Real-time update rate of 4 Hz — sufficient for monitoring slow drift or comparative magnet grading
- Battery-powered operation (9 V alkaline) with >100 hours of continuous use and low-battery indicator
Sample Compatibility & Compliance
The GM1-ST is compatible with permanent magnets (NdFeB, SmCo, ferrite), electromagnets, magnetic assemblies, and magnetic shielding materials. Its non-contact, passive Hall probe requires no excitation current and introduces negligible field perturbation. The sensor head is RoHS-compliant and rated for industrial environments (IP42 enclosure rating). While not certified to ISO/IEC 17025 as a standalone calibration system, the instrument supports GLP-compliant documentation when paired with Alphalab’s optional NIST-traceable calibration certificate (Model CAL-GM1-ST). It meets general requirements for magnetic field verification under ASTM A977/A977M (Standard Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials) for relative strength assessment and consistency checks.
Software & Data Management
The GM1-ST operates as a stand-alone analog readout device with no onboard data logging or PC interface. However, its stable analog output (0–2 V DC proportional to field strength) is accessible via the rear-panel BNC connector and compatible with third-party DAQ systems (e.g., National Instruments USB-6009, Keysight 34972A) for time-series capture, statistical process control (SPC), or integration into automated test fixtures. When used in regulated environments (e.g., medical device magnet testing per ISO 13485), users may implement manual audit trails, including operator ID, timestamp, sensor position notes, and reference standard IDs — satisfying basic FDA 21 CFR Part 11 record-keeping expectations for non-electronic-record-critical applications.
Applications
- Quality control of sintered NdFeB and SmCo magnets during manufacturing and final inspection
- Verification of magnetic field uniformity across pole faces and air gaps in DC solenoids and C-frame electromagnets
- Monitoring magnetic aging or demagnetization in motor rotors, MRI shimming arrays, and magnetic separation equipment
- Characterizing remanent field strength after magnetization cycles in production tooling
- Educational labs for demonstrating magnetic dipole fields, inverse-square law validation, and material permeability comparisons
- Field mapping of magnetic encoders, Hall-effect sensor placement validation, and EMI source localization
FAQ
Does the GM1-ST measure AC magnetic fields?
No — the GM1-ST is designed exclusively for static (DC) magnetic field measurement. It does not respond to time-varying fields above ~0.5 Hz.
Can the sensor be recalibrated in-house?
No — the Hall sensor is factory-calibrated and sealed. Recalibration requires return to Alphalab or an authorized service center with traceable Helmholtz coil standards.
Is the 0.1 G resolution maintained across the entire range?
Yes — resolution is constant at 0.1 G from 0.0 to 19,999.9 G due to the fixed-gain, high-resolution ADC architecture.
What is the typical accuracy specification?
Accuracy is ±2% of reading ±5 digits at 23 °C, referenced to Alphalab’s internal calibration standard; full specifications are provided in the user manual (Rev. D or later).
Can the sensor withstand exposure to strong fields beyond 20 kG?
Prolonged exposure above 20,000 G may cause irreversible sensor drift or saturation; operation within the specified 0–19,999.9 G range is required for guaranteed performance and warranty validity.
