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2022-02-10 8:07 pm
I'm trying to see if I can finalise a simple project using an ESP8266, a PIR sensor and an AHT10 temperature/humidity sensor.
Does an ESP8266 need ventilation for a little bit of cooling? Most of my ESP8266s and ESP32s run fairly cool, so I don't think so, but it's worth asking.
Also, do I need ventilation into the box to prevent the AHT10 sensor from registering the temperature inside the box, instead of the room itself? If that makes sense. I assume the interior of the box might be slightly different to the room.
Thanks
2022-02-10 9:09 pm
Hi @yurkshirelad,
Sounds like you have the general principles sorted, and maybe just need to look carefully at your actual system. If you are making a bit of general purpose measurment kit to go on sale, then you will generally look to get the most accurate results/highest specification (hoping this will mean the highest selling price), whilst keeping to a budget of both materials and design effort. You need to adjust this paradigm to your own situation.
At the risk of repeating the obvious, a sensor can (at best) report its own situation ... if it is being heated by a couple of degrees (say) above the general atmosphere, it will report a temperature a couple of degrees higher .. and so on. Remember heating can be from both nearby sources (e.g. ESP8266) and itself, assuming it is a powered device. Sometimes, the latter can be particularly troublesome, as any power consuming parts within the device are likely to be thermally coupled to the sensor, but hopefully not here.
Similarly, the humidity sensing can be affected if it is 'sealed' away from the atmosphere. So for the most accurate results, do your best to thermally separate the sensor from any part that consumes power, permit the sensor to actually sense the air it is supposed to be measuring, whilst avoiding local draughts, etc.
Also, consider minimising the power consumption .. does the ESP8266 need to be processing all the time or can it sleep most of the time, just 'waking up to take a measurement every minute (say). Before spending a lot of time doing this 'properly', consider seeing what happens when you switch on from 'cold', and watching over (say) an hour. I am not sure about this particular sensor, but you may need to have it powered up and stabilised for some time before powering upp the ESP. (Check the sensor data sheet for hints.. you may see something like 15 minute warm up time...I haven't looked, so it is only a reminder to check.)
So, sorry I cannot tell you whether factors like ESP8266 power dissipation is affecting your readings, because it depends upon your individual design. However, if a board is consuming say 100mA at 5V, then 500mW must be dissipated somewhere, and that means something must be above the ambient temperature ... you do not want your sensor to be the main radiator for this heat!
Good luck .. Dave
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