strain gauge data logger

Strain gauge data loggers need to match the bridge configuration and excitation requirements of the sensors they connect to. Kingmach units are built around three main design constraints: input flexibility, signal conditioning, and data accessibility. On the input side, models accept quarter-bridge (120Ω or 350Ω with internal completion), half-bridge, and full-bridge sensors. The excitation voltage is selectable—commonly 2.5V or 5V—so they work with standard foil gauges without overdriving low-resistance elements. Some multi-channel versions support mixed bridge types on the same unit, which saves hardware cost when monitoring different sensor types on one structure. Signal conditioning isn’t just gain and zero-offset adjustment. The front-end includes programmable gain amplifiers that auto-range to the input signal, reducing the need for manual scaling. Filtering can be set per channel: low-pass filters with cutoff frequencies from 1Hz to 1kHz help suppress mechanical noise in strain signals. For long-duration geotechnical jobs, anti-aliasing filters are particularly important where the sampling rate might be dropped to conserve storage. Data storage and retrieval are where many loggers frustrate users. Kingmach devices typically store to removable SD cards or internal flash, with capacities from 8GB upward. The file format is CSV or a compressed binary with timestamps synchronized to a real-time clock that holds accuracy within ±15 seconds per month—enough for most non-seismic work. Remote data access via RS-485 or optional 4G modem lets you pull data without visiting the site, which in remote monitoring applications saves more field time than any hardware feature. Export to third-party software like LabVIEW or MATLAB is supported through documented ASCII command sets, not just proprietary viewers. Power consumption matters because field jobs run on battery and solar. By default, the logger sleeps between scheduled readings, drawing under 100µA in standby. Wake-up from a digital trigger input or alarm threshold allows event-driven recording without continuous power drain. This sleep-wake architecture combined with signal-compatible inputs is what separates a logger that just works on a quick test from one that can run a 6-month pile monitoring job without site visits.