wheatstone bridge strain gauge

A Wheatstone bridge strain gauge works on a simple premise: a resistive foil pattern deforms with the test surface, and that deformation alters the resistance. The bridge converts this change into a measurable voltage. What gets complicated is making sure the numbers stay reliable across temperature swings, long cable runs, and less‑than‑ideal surface finishes. Kingmach supplies gauges with standard resistances—commonly 120 Ω, 350 Ω, and sometimes 1000 Ω for low‑power or long‑range applications. The gauge factor typically sits around 2.0 for constantan foil, and the grid patterns range from single‑axis linear designs to stacked rosettes for biaxial stress analysis. One parameter that does not show up on datasheets but matters in practice is lead‑wire desensitization. When you add extension cables to a quarter‑bridge setup, the extra resistance acts like a voltage divider and can drop the apparent strain reading by a few percent. Three‑wire quarter‑bridge connections compensate for most of this, and all Kingmach gauges support that wiring right out of the package. For installations that need full‑bridge configuration, the built‑in temperature compensation curve is matched to common structural materials—steel, aluminum, and concrete. The self‑temperature compensation (STC) number on the gauge packaging tells you which material it’s intended for; using an STC‑13 gauge on aluminum will give you more thermal output than you probably want. Compatibility with data acquisition systems is mostly about excitation voltage and signal‑to‑noise ratio. Most loggers supply 2.5 V or 5 V excitation. At 350 Ω, a 5 V supply puts about 14 mW into the bridge, which is fine for static readings but can cause self‑heating drift on thin polymers. Kingmach’s specification sheets list the recommended excitation range for each grid size and backing material, so you can avoid that trap. For projects where off‑the‑shelf gauges don’t fit, we routinely adjust grid length, backing thickness, and solder pad layout—small changes that make installation faster without altering the bridge behavior. Since the company operates a global distribution network, technical questions about gauge compatibility with specific loggers (Campbell Scientific, HBM, National Instruments, etc.) get answered from field experience rather than generic manuals.