# Signal conditioning

Raw sensor signals are often tiny or noisy. Conditioning amplifies and filters them so the ADC can measure them well.

Page: https://dharanova.com/learn/signal-conditioning · Track: Sense · Level: Core · Facts last checked 6 October 2026

Read first: [What a sensor actually is](https://dharanova.com/learn/what-is-a-sensor.md), [Analog-to-digital conversion](https://dharanova.com/learn/adc-basics.md)

Diagram: A Wheatstone bridge of four resistors, one of them a strain gauge, is powered by 5 V excitation. Its two middle points give a small differential voltage, in millivolts; a note adds that a load cell rated 1 to 3 mV/V gives about 5 to 15 mV at full load. That pair feeds an amplifier (an instrumentation amplifier or the ADC's programmable gain), then a low-pass anti-aliasing filter, then the ADC. The filter cuts frequencies above half the sampling rate, which would otherwise fold back as false lower-frequency signals.

## Key points

1. Resistive sensors such as strain gauges are usually wired as a Wheatstone bridge, which turns a tiny change in resistance into a small differential voltage centred near zero. [1]
2. Load cells specify rated output in millivolts per volt of excitation, typically 1 to 3 mV/V, so a 5 V excitation gives only about 5 to 15 mV at full load, which needs amplification (an instrumentation amplifier or the ADC's programmable gain) before conversion. [1]
3. An analog low-pass (anti-aliasing) filter before the ADC attenuates frequencies above half the sampling rate, which would otherwise fold back into the measurement as false lower-frequency signals. [2]

## Where to go next

- [Taking a load cell apart until it makes sense](https://dharanova.com/inside-a-load-cell.md): an engineering note from our team
- [Uncalibrated bench characterisation of low-cost turbidity, TDS, pH and level sensors on Arduino Uno R4 WiFi](https://dharanova.com/whitepapers/uncalibrated-water-sensors-arduino-uno-r4-wifi.md): a whitepaper from our lab

## Sources

1. [A Basic Guide to Bridge Measurements (SBAA532A)](https://www.ti.com/lit/an/sbaa532a/sbaa532a.pdf), Texas Instruments
2. [TI Precision Labs: Aliasing and Anti-aliasing Filters (TIPL 4304) slides](https://www.ti.com/content/dam/videos/external-videos/en-us/2/3816841626001/5831231183001.mp4/subassets/adcs-aliasing-and-anti-aliasing-filters-presentation-quiz.pdf), Texas Instruments