![]() Since the dew point is an absolute number it is often used to define "how Onto the water when the temperature falls i.e. Below theĭew point water will saturate out onto solid objects since the air can not hold ![]() It is the temperature at which the air is saturated with water. If you want to know what the air "feels like" then this is the parameter to It is the amount of moisture in the air compared to the amount that the air can You can think of relative humidity as "how close the air is to saturation". ![]() What is Relative Humidity and the Dew point? Relative Humidity Note: The DHT11 is also known as the RHT01. The DHT22 is also known as the RHT03 - the following datasheet references RHT03. canīe changed from input to output on the fly. To have a dedicated processor pin and this pin must be bi-directional i.e. Single-Master-Slave only, meaning that each DHT11 you use has Warning: The serial protocol used is strictly Note : The AM2302 is similar to the RHT03 but has a lower max.cable Voltage successfully, so you you will need a smaller pull-up resistor. Resistor is not defined and you have to find it experimentally - for a longerĬable, resistance increases, therefore you need more current to pull up the If you use more than a 20m cable run then the The data sheet indicates it can cope with a cable length of more than 20m.įor less than 20m a 5k pull-up is recommended (most breakout boards have this 1 second 2s Manufacturer MaxDetect Technology Co. Paramet er DHT11 (RHT01) DHT22 (RHT03) Relative Humidity Range 20 ~ 90% 0 ~ 100% Relative Humidity Accuracy: ±5%RH ☒%RH Temperature Accuracy: ☒☌ ☐.5☌ Resolution 1%RH,1☌ 0.1%RH,0.1☌ Repeatability ☑% ☑% Long Term Stability ☑% per year ☐.5% per year Operating Temperature Range 0 ~ 50☌ -40 ~ 80☌ Power Supply: 3,3V ~ 5.5V 3.3 ~5.5V Supply Current: 0.5mA ~ 2.5mA 1 ~ 1.5mA Idle Supply Current: 100uA ~ 150uA 40 ~ 50uA Max sampling period DHT22 vs DHT11 (difference) Specifications: RH may not indicate this (see videos below to understand this difference). ThisĪllows you to assess the comfort level of the air i.e. Measure since it produces an absolute number (the dew point temperature). Working out the dew point can be a better Misleading concerning the actual water content in the air (which changes with The sensor measures Relative Humidity and this is sometimes See the device specifications for details. However note that it is not that accurate for theĭHT11 It is quite good for the DHT22. Both of these sensors measure temperature and as a bonus you can To measure humidity accurately you have to know the temperature as, to a largeĮxtent, the humidity of a gas is dependent on temperature.
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