LVDTer

LVDTer (short for Low-Voltage Linear Variable Differential Transformer) is a class of displacement sensors derived from the traditional linear variable differential transformer (LVDT). It is designed to operate at reduced excitation voltages while maintaining a high-resolution, linear output over a defined sensing range. LVDTer devices typically provide an AC differential voltage on secondary windings, which is conditioned to produce a DC or digital signal proportional to core displacement.

Construction and operation: Like an LVDT, an LVDTer consists of a movable ferromagnetic core threaded through a coil assembly composed of a primary excitation coil and multiple secondary windings arranged around a hollow tube. The core position modulates the mutual inductance between the coils, generating a differential voltage that can be amplified and processed. In a low-voltage variant, excitation voltages are in the range of a few volts or less, and integrated signal-conditioning electronics perform demodulation, offset correction, temperature compensation, and conversion to a standard output.

Variants and integration: Standard LVDT-like configurations may be adapted with onboard electronics, producing ratiometric DC outputs, or with digital interfaces (SPI/I2C) for direct microcontroller integration. Some implementations emphasize miniaturization, in which the entire sensor and conditioning are packaged in a compact capsule.

Applications and advantages: LVDTer sensors are considered for space-constrained or safety-critical environments where high sensitivity is required but high excitation voltages are undesirable, such as aerospace instrumentation, robotics, and precision metrology. They offer non-contact measurement, good linearity, and robustness to environmental factors. Limitations include the need for careful magnetic shielding, calibration, and potentially higher cost due to advanced conditioning electronics.