APD 4059 - Strain Gauge Bridge/Load Cell to DC Transmitter - Field Configurable - Isolated

The APD 4059 Strain Gauge to DC Isolated Transmitter is a high-performance, field-configurable signal conditioning module designed to convert low-level millivolt signals from strain gauges, load cells, bridge sensors, and pressure transducers into stable, isolated DC voltage or current outputs.

Engineered for industrial weighing, force measurement, and pressure monitoring applications, the APD 4059 provides precise amplification, filtering, and scaling of bridge-based sensor signals while maintaining exceptional accuracy and long-term stability.

Precision Signal Conditioning for Bridge-Based Sensors

Strain gauge and load cell sensors produce very low-level signals, typically in the millivolt-per-volt (mV/V) range. These signals require precise amplification and conditioning before they can be used by control systems.

The APD 4059 is specifically designed to:

• Accept low-level millivolt signals from bridge sensors

• Provide stable excitation voltage

• Amplify and filter the signal

• Convert it into a linear DC output

This ensures accurate and reliable measurement of force, weight, pressure, or strain.

Wide Input Compatibility for Maximum Flexibility

The APD 4059 supports a broad range of strain gauge and bridge sensor inputs:

• Bridge resistance: 100 Ω to 10,000 Ω

• Sensitivity range: 0.5 mV/V to 40 mV/V

• Input signal range: as low as 5 mV up to 400 mV

It can drive:

• Up to four 350 Ω load cells simultaneously

• A wide variety of strain gauge configurations

This flexibility makes it suitable for both single-sensor and multi-sensor systems.

Adjustable Excitation Voltage for Sensor Optimization

The APD 4059 features a built-in, adjustable excitation power supply:

• Selectable range: 0 to 10 VDC in 1 V increments

• Fine adjustment: ±5% via potentiometer

• Stability: ±0.01% per °C

Providing a stable excitation voltage is critical for maintaining sensor accuracy and repeatability. The APD 4059 ensures consistent excitation even under changing environmental conditions.

Sense Lead Compensation for Improved Accuracy

Lead wire resistance can introduce measurement errors, especially in remote sensor installations.

The APD 4059 includes sense lead compensation, which:

• Monitors voltage at the sensor

• Automatically compensates for voltage drops in wiring

• Maintains accurate excitation at the bridge

This feature significantly improves measurement accuracy in real-world installations.

Field Configurable Input, Output, and Offset

The APD 4059 is fully field configurable using external switches, allowing for rapid setup and adaptation.

• Configure input range, output range, and excitation voltage

• Select offset adjustment up to ±100% of span

• Adjust zero and span independently (non-interactive)

This flexibility enables the module to support hundreds of input/output combinations without requiring factory reconfiguration.

Flexible Output Options for System Integration

The APD 4059 provides multiple output options for compatibility with industrial systems:

Voltage Outputs:

• 0–1 V, 0–5 V, 0–10 V

• Bipolar ±5 V or ±10 V

Current Outputs:

• 0–2 mA, 0–10 mA, 4–20 mA

• Supports sink or source current output configurations

• Up to 20 V compliance at 20 mA

This ensures seamless integration with PLCs, data acquisition systems, recorders, and controllers.

Full 3-Way Isolation for Signal Integrity

The APD 4059 provides complete isolation between input, output, and power circuits:

• Isolation rating: 1200 VRMS minimum

Benefits include:

• Elimination of ground loops

• Improved noise rejection

• Protection of sensitive equipment

• Enhanced system reliability

Built-In Calibration and Offset Compensation

The APD 4059 includes advanced calibration features to simplify setup:

• Multi-turn zero and span adjustments

• Offset switch for tare and deadweight compensation

• Internal or external calibration resistor options

Offset adjustment allows users to:

• Compensate for pre-load or tare weight

• Align sensor output to zero under load conditions

• Adjust for sensors with inherent offsets

This flexibility is critical in weighing and force measurement systems.

LoopTracker® LEDs for Real-Time Monitoring

The APD 4059 includes LoopTracker LEDs for visual diagnostics:

• Green LED: indicates input signal level

• Red LED: indicates output signal level

LED brightness changes with signal intensity, providing instant feedback on system operation and simplifying troubleshooting.

Output Test Function for Easy Commissioning

A built-in test function allows users to simulate an output signal:

• Adjustable from 0% to 100% of output span

• Independent of input signal

This feature simplifies system startup, calibration, and diagnostics.

High Accuracy and Stable Performance

The APD 4059 is designed for precision measurement:

• Accuracy: ±0.1% of span

• Temperature stability: ±0.02% per °C

• Response time: 70 ms typical (optional 10 ms)

These specifications ensure reliable and repeatable performance in demanding industrial environments.

Rugged Industrial Design

The APD 4059 is built for long-term reliability:

• Operating temperature: –10°C to +60°C

• DIN rail mounting (35 mm standard)

• Compact 22.5 mm housing

• IP40 enclosure (panel mounting required)

• Removable terminal blocks for easy installation

Typical Applications

The APD 4059 is ideal for a wide range of industrial measurement applications:

• Load cell weighing systems and scales

• Tank and silo weighing

• Crane and lifting load monitoring

• Extruder melt pressure measurement

• Strain gauge pressure transducers

• Force and tension measurement systems

Why Use a Load Cell Signal Conditioner?

Raw strain gauge signals are:

• Extremely low level

• Susceptible to noise

• Dependent on stable excitation

A signal conditioner like the APD 4059 provides:

• Amplification and filtering

• Stable excitation voltage

• Signal isolation

• Conversion to standardized outputs

Why Choose the APD 4059?

The APD 4059 stands out due to its:

• Wide input compatibility (load cells, bridges, pressure sensors)

• Adjustable excitation with high stability

• Sense lead compensation for accuracy

• Field-configurable input, output, and offset

• Full 3-way isolation

• Sink/source current output flexibility

• Calibration and diagnostic features

• Rugged industrial design

A Complete Solution for Load Cell and Strain Gauge Signal Conditioning

The APD 4059 Strain Gauge to DC Isolated Transmitter provides a complete solution for converting low-level bridge signals into reliable, usable outputs. Its combination of precision, flexibility, and durability makes it an essential component in industrial measurement and control systems.

Optimize Your Measurement System

Whether you are designing a weighing system, integrating pressure sensors, or improving signal reliability, the APD 4059 delivers the performance needed for accurate and dependable operation.

Contact us today to learn more or configure a solution for your application.