dht11/22 max. wire length

[BartSr]

Hi, I cannot find documentation telling me what is max length of wiring of temp/ huminity sensor dht11/12.
Any idea where to find?
Bart

[Ath]

As usual, wiring carrying pulses od data should be as short as reasonably possible. Sensible max. length should be between 50 and 100cm. Can be somewhat longer when using a shielded and twisted cable, like s(f)tp, where the shield is connected to gnd at the ESP side.

[TD-er]

Not sure if there is a stated max. length.
I guess it will be hard to see if it is working 'better' or 'worse', as those really aren't the best sensors.

I think adding a small capacitor (e.g. 100 nF) over VCC and GND close to the sensor will help suppressing picked up noise and voltage fluctuations.
And using twisted wire for data and GND is probably a good idea.
So if you plan on using something like UTP, I would use 1 pair for VCC and GND and 1 pair for data and GND.

[BartSr]

Thanks a lot. A already was afraid for longer lenghts. Are you familar with sensor allowing longer length, say 3 or 4 meter. or a reliable battery supplied sensor. I want to control a shower exh. fan.
Bart

[TD-er]

Well I guess you should just try it.
Since there is only a single sensor connected to it, it might just work.

If you're looking for only a temperature sensor, maybe a 1-Wire sensor like the DS18b20 might be an option?

[BartSr]

Wel, in fact the esp32 on which I want to hook on a humidity sensor is already loaded with 13 dallas temp-sensors. A tempsensor might be no problem whereas also long wiring is possible. But I need to monitor the humunity op the bathroom to see if the ex. fan must be activated at high speed