ADInstruments ML228 Octal Bridge Amp

The ADInstruments ML228 Octal Bridge Amp is an eight-channel front-end amplifier for PowerLab systems, delivering precise signal conditioning from DC bridge transducers. It amplifies physiological signals across force, displacement, pressure, temperature, and light measurement applications with ±0.5% accuracy and software-controlled zeroing.

Technical Specifications

• 8 independent channels with differential input configuration


• Gain range: ±200 μV to ±5 V full scale in 14 steps (±5 V, ±2 V, ±1 V, ±500 mV, ±200 mV, ±100 mV, ±50 mV, ±20 mV, ±10 mV, ±5 mV, ±2 mV, ±1 mV, ±500 μV, ±200 μV)


• Amplification accuracy: ±0.5% (combined with PowerLab)


• Input impedance: 2 MΩ (differential), 2 × 1 MΩ (single-ended)


• Maximum input voltage: ±10 V Signal Conditioning:


• Common-mode rejection ratio: 100 dB at 50 Hz (typical)


• Input noise: <1 μV


• Frequency response (-3 dB): 2 kHz maximum at all gains


• Low-pass filtering: 1 Hz to 2 kHz in eight software-selectable steps


• Internal offset range: ±10 V (1–5 V), ±1 V (100–500 mV), ±100 mV (200 μV–50 mV)


• Internal offset resolution: 16-bit DAC, ±32,000 steps about 0 V Transducer Interface:


• Eight-pin DIN socket inputs per channel


• Excitation voltage: 0–20 V DC (±10 V referred to ground), externally adjustable


• Transducer drive current: ±45 mA maximum


• Supports powered bridge transducers and certain low-impedance unpowered transducers


• Compatible with Grass transducers via MLAC11 adapter cable

Key Features

• Software-controlled manual or automatic zeroing with fast engagement


• Individual overload indicator light per channel (illuminates on out-of-compliance conditions)


• BNC analog output sockets on rear panel


• Power consumption: 5.0 W (without transducers)

Typical Applications Force and strain measurement, displacement and position sensing, pressure transduction, temperature monitoring, and light intensity quantification in physiological research.

Compatibility & Integration Connects to PowerLab systems via I2C port (power and control bus). I2C communication rate approximately 50 Kbits/s. Multiple front-end units supported depending on PowerLab model.