Can you use two different sensors with 5V and 3.3V, both with analog inputs ?

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coprez
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Can you use two different sensors with 5V and 3.3V, both with analog inputs ?

Post by coprez » Sat Jul 14, 2018 6:52 pm

Can you use two different sensors with 5V and 3.3V, both with analog inputs ?

I have a temperature sensor that requires 5V and the sparkfun Air quality sensor that has a limit of 3.3V. I need both to be connected to separate analog inputs, A0 and A1 on the Sparkfun redboard. Both sensors connect to the same ground in my circuit on the arduino. Will the voltage difference cause issues?

oesterle
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Re: Can you use two different sensors with 5V and 3.3V, both with analog inputs ?

Post by oesterle » Wed Aug 01, 2018 6:40 pm

Exactly which sensors are you using?

jremington
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Re: Can you use two different sensors with 5V and 3.3V, both with analog inputs ?

Post by jremington » Thu Aug 02, 2018 10:21 am

Should be no problem.

Valen
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Re: Can you use two different sensors with 5V and 3.3V, both with analog inputs ?

Post by Valen » Sat Aug 04, 2018 7:45 am

If the sensors are analog then it should be no problem. But are they!?! If I look at what Sparkfun has to offer then there are various temperature sensors. Please be more specific which one you intend to use.

The air quality sensor (https://www.sparkfun.com/products/14193) is mostly a digital sensor, communicated with over (digital) I2C. And that will cause a problem if it is operated at 5 volt. The chip has an absolute limit to 3.6 volt. Only the NTC-thermistor would provide an analog voltage based on temperature (if it is soldered in and connected to one of the analog inputs). That voltage will not reach above 3.3 volt. However, the sensor chip already provides a means of reading the voltages of both the NTC and reference resistor down to 1 vmiliVolt. (Much )better than the Redboard can with it's 1024-bit resolution.

So the proper question is, why should you? And is it not really digital (I2C)?

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