CJMCU-29 INA129-HT Precision Low Power Instrumentation Amplifier Module

Specifications

• Amplifier IC: INA129-HT

• Operating Temperature: -55°C to 210°C (Extreme High Temp)

• Power Supply Requirement: ±2.25V to ±18V (Dual / Bipolar Supply)

• Gain Range: 1 to 10,000 (Adjustable via onboard potentiometer)

• Quiescent Current: 2 mA (Low Power)

• Offset Voltage: 25 μV (Typical)

• Input Protection: Overvoltage protection up to ±40V

• Pinout (Silkscreen 'U' denotes Voltage 'V'): UIN-, UIN+, U-, U+, VO, GND

Key Applications and Projects

• Industrial Sensor Interfaces: Amplifying weak signals from strain gauges, RTDs, and thermocouples deployed in foundries or industrial ovens.

• Medical & Biometric Monitoring: Building custom ECG or EMG circuits where extreme noise rejection is required to read tiny electrical impulses from the human body.

• Precision Data Acquisition: Conditioning raw analog signals before feeding them into high-resolution Analog-to-Digital Converters (ADCs) for data logging.

Unlock New Capabilities (Project Evolution)

• Dual Supply Integration: To get the cleanest, most linear response out of this module, pair it with a Dual Output DC-DC Charge Pump to provide it with a dedicated, isolated +12V and -12V power supply.

Package Includes:

• 1 x CJMCU-29 INA129-HT Precision Low Power Instrumentation Amplifier Module

FREQUENTLY ASKED QUESTIONS (FAQ)

1. What is the difference between an instrumentation amplifier and a normal op-amp? An instrumentation amplifier (like the INA129) contains multiple internal op-amps and laser-trimmed precision resistors. It is designed specifically to amplify differential signals while fiercely rejecting common-mode noise, making it vastly superior for reading raw sensors.

2. What does "HT" stand for? HT stands for High Temperature. This specific chip is rated to operate reliably up to 210°C.

3. What power supply do I need for this module? It is designed for a dual (bipolar) power supply, meaning you need a positive voltage (e.g., +5V), a negative voltage (e.g., -5V), and a common Ground. It accepts ±2.25V up to ±18V.

4. Can I run it on a single supply (like 0V and 5V)? While technically possible if you artificially bias the reference pin, this board ties the reference to GND. It is highly recommended to use a true dual supply for proper linear operation.

5. How do I adjust the amplification (gain)? Use a small flathead screwdriver to turn the tiny metal dial on the onboard trimmer potentiometer.

6. What is the mathematical formula for the gain? The gain for the INA129 is calculated as: Gain = 1 + (49.4k Ohms / Rg) where Rg is the resistance of the onboard potentiometer.

7. What are the UIN+ and UIN- pins? These are your differential inputs. You connect your sensor's positive and negative signal wires here. (Note: The silkscreen uses 'U' for Voltage).

8. What is the VO pin? This is the Voltage Output. It provides the final amplified analog signal that you connect to your microcontroller's ADC.

9. What are the U+ and U- pins on the header? These are your power inputs. Connect your positive power rail to U+ and your negative power rail to U-.

10. What are the two large empty holes labeled U+ and U- on the side? These are duplicate, heavy-duty connection pads for your power supply. They are useful if you want to solder thicker power wires or add large external bypass capacitors directly to the board.

11. Will this work with an Arduino or Raspberry Pi? Yes, you can connect the VO pin to an analog input (ADC) on an Arduino. However, ensure the output voltage does not exceed your microcontroller's maximum logic limit (usually 3.3V or 5V).

12. Why does the chip have a "BB" logo? BB stands for Burr-Brown, a legendary manufacturer of ultra-precision analog ICs that was acquired by Texas Instruments. TI continues to use the logo on this premium line.

13. Is it safe to use in a noisy electrical environment? Yes, the INA129 features an excellent Common-Mode Rejection Ratio (CMRR) of ~93 dB, making it highly immune to ambient electrical noise.

14. What happens if I accidentally send a large voltage into the sensor pins? The INA129 features internal input protection that can withstand overvoltage up to ±40V without sustaining damage.

15. Does the board come with the header pins soldered? No, it typically arrives as a bare PCB. You will need to solder your own 2.54mm header pins.

16. Can I use this for a load cell (weight scale)? Absolutely. It is an excellent, high-precision alternative to the common HX711, provided you use an ADC to read the analog output.

17. Is it good for reading thermocouples? Yes, the microvolt changes of a thermocouple are easily and cleanly amplified by this module.

18. Does this module filter out high-frequency noise? The INA129 is primarily an amplifier. While its bandwidth drops at higher gains, it does not have a dedicated, heavy low-pass filter onboard. You may need to add an RC filter to the output if dealing with extreme RF noise.

19. What is the quiescent current? The chip is considered low-power and draws only about 2mA of current while resting.

20. Can I use this to amplify audio? While it could amplify an audio signal, it is designed for low-frequency, DC-coupled instrumentation signals. It is not optimized for driving speakers or high-fidelity audio applications.