Humidity Sensors

More Information about Humidity Sensors

Relative humidity sensors are commonly used in a wide range of applications, including HVAC systems, weather stations, industrial control systems, and even smartphones and wearable devices. These sensors can provide accurate monitoring of humidity, which is important for comfort, energy efficiency, and in some cases, the proper functioning of equipment.

The performance of a humidity sensor can be influenced by the surrounding environment, including temperature and pressure. Therefore, many humidity sensors are combined with temperature sensors to provide temperature-compensated humidity measurements. In addition, these sensors require calibration to ensure their accuracy and repeatability.

Digital humidity sensors provide a digital output that can be easily interfaced with microcontrollers and other digital systems. The output is usually proportional to the measured humidity, and can be converted into units of relative humidity (RH) by using calibration data provided by the sensor manufacturer.

For accurate measurements and longevity, humidity sensors need to be protected from extreme conditions such as high temperatures and pressures, and from contaminants that can damage the sensor or affect its operation.

FAQs

What is absolute humidity?

Absolute humidity is a measure of the total amount of water vapor present in a given volume of air. It is usually expressed in grams of water vapor per cubic meter of air (g/m³). This is unlike relative humidity, which is the ratio of the current amount of water vapor in the air at a given temperature to the maximum amount of water vapor the air could hold at that temperature, expressed as a percentage.

Is there a particular sensor that will measure the dew point, humidity and temperature?

Yes, there are sensors known as combined or multi-parameter sensors that can measure dew point, humidity, and temperature. One example of this is a capacitive humidity sensor.

How accurate is a temperature sensor at measuring the temperature of the surrounding air?

To accurately measure temperature of the surrounding air, will depend on the sensor type, sensor quality, calibration, environment and signal conditioning.

Analog and Digital Control Signals: The Basics

Digital Signals

Digital signals are represented in either a true or false. There is no gray area with digital signals. An example of this might be a light switch. A light switch is either on or off. Another example of this might be a motor that is running or not running. Digital signals can be generated with both AC and DC circuits with varying voltages, currents and resistance. Some practical examples of using digital signals in an industrial environment might be if a pump is running or not running or a whether a valve is open or closed.

Analog Signals

Analog signals convey information in the form of a range. A light switch might be on or off as a digital signal, but a dimmer switch would be an analog signal. It can be on or off, but it can also be somewhere in between. A practical example of using analog signals in an industrial environment would be if there is a need to measure the level of a tank; whether it's full, empty or somewhere in between. Analog signals can take many different forms with some of the more common being a 4 to 20 milliamp signal or a 0 to 5 or 0 to 10 volt signal. 

Communication

Communication in a device can either be sent or received. Whether that data is sent or received depends on the type of information. Is there a need to monitor the status of something? If so, an input needs to be received about that information. Is there a need to control something? If so, an output needs to be sent about what needs to occur. Receiving inputs and setting outputs are both things that can be accomplished by using both digital and analog signal types. Therefore, the signals are referred to as analog outputs (AO), analog inputs (AI), digital inputs (DI) or digital outputs (DO).