Description
The 50kg Half-Bridge Load Cell is a strain-gauge-based weight sensor designed for digital body scales, platform scales, and other electronic weighing applications. It consists of an aluminum alloy (or alloy steel) E-shaped beam with two strain gauges bonded to the inner and outer surfaces of the central beam. When force is applied to the center button, the beam flexes, causing one gauge to stretch (tension) and the other to compress, producing a differential resistance change proportional to the applied load .
Because this is a half-bridge configuration, it provides only half of a complete Wheatstone bridge. To use it, you must either combine it with a second identical half-bridge cell (forming a full bridge with doubled capacity) or complete the bridge with two precision resistors. For a standard body scale, four 50kg cells are typically used—one under each corner—wired together in a ring to form a full bridge with a combined capacity of 200kg .
The sensor connects via three wires: red (center tap/signal), white and black (bridge ends). The resistance between white-red and red-black is approximately 1kΩ each, with about 2kΩ end-to-end . The output sensitivity is approximately 1.0 mV/V at rated load, requiring a high-gain amplifier like the HX711 (gain 128) to produce a usable digital signal .
Critical limitations: This sensor cannot be used alone. It requires a bridge completion circuit and a precision ADC amplifier. The HX711 is the standard companion for this cell. Mechanical mounting is critical—the center button must carry the load while the outer rim sits on a rigid mounting ring. Improper mounting (e.g., load on the rim, or uneven pressure) will produce inaccurate or unstable readings .
Features
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Half-Bridge Strain Gauge Design: Requires bridge completion (second cell or resistors) for full operation .
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50kg Capacity per Cell: Four cells combined yield 200kg platform capacity .
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Aluminum Alloy/Alloy Steel Construction: Durable E-shaped beam with raised center load button .
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High Accuracy: Nonlinearity and repeatability of ±0.03% FS .
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Three-Wire Interface: Red (signal), White and Black (bridge ends) .
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Compact Size: Approximately 34×34mm, 7.8mm thick, with 14mm center button .
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Low Cost: Inexpensive sensor for DIY scale projects.
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Widely Used: Standard choice for digital body scales and platform scales .
Technical Specifications
| Parameter | Specification |
|---|---|
| Sensor Type | Half-bridge resistive strain gauge |
| Rated Capacity | 50 kg per cell |
| Material | Aluminum alloy (verify; some list alloy steel) |
| Output Sensitivity | ~1.0 mV/V |
| Nonlinearity | ±0.03% FS |
| Repeatability | ±0.03% FS |
| Input Resistance | ~1 kΩ per half-bridge |
| Dimensions | Approx. 34 × 34 × 7.8 mm |
| Wiring | Red = signal, White/Black = bridge ends |
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