reading multiple analog sensors

[czahn]

Hi !
i have two sensors. A moisture and a photoresistor. I'd like to use both together with a wemos d1 mini, which only has one analog input.
I already wired the vcc to several gpio's and defined a switch to power on/off the sensors. Both Analog output goes to A0 on the wemos.
Now i can switch between the senors, so that only one sensor has power.

Unfortunately the measurements for both senors are not correct. When i connect only one sensor to A0, everything works fine and the measurements are correct.

What do i wrong! Is there any trick?

Thanks a lot!
Regards.
C

[Shardan]

Hello,

as both sensors are permanently connected to the analog input they influence each other. Sorry, that won't work.
There are several ways out.

First you could replace the photo resistor with a luminosity sensor like TSL2561 or BH1750.

Second you could use a relay to switch the analog input itself instead of powering the sensors via GPIO.

Third you may use an external analog-to-digital converter (ADC) like the ADS1115.

Regards
Shardan

[papperone]

3rd solution is the easiest and safer IMHO!