I am looking to measure the temperature of an aqueous solution using a probe with threading, the XTP25N-050-0100C from Automation Direct. First off, this sensor gives 4-20 mA signal, and I was wondering if I could use this chip, a SEN0262 from DFRobot, an " Analog Current to Voltage Converter" to convert the analog current logic to analog voltage logic to be read by the Arduino's analog pins. I was thinking of connecting it as seen in this application demo:
I would be using a 24 V power source to power the sensor, and be reading the current with the chip, then reading the chips voltage with an Arduino. Does anyone seen an issue with this plan?
As always, I am grateful for any responses and I would be more than willing to elaborate if I missed a point. I have further questions eventually, but not at this moment.
Even if the voltage needed for the sensor is 24 v? Would it be wired like this? Just measure the voltage on each side of the resistor? Thank you for your response, I appreciate it.
You have to make sure the 24V sensor supply voltage can NEVER be applied to an Arduino pin, it would be instantly destroyed. The 27k series resistor in the following schematic prevents current of more than 1mA flowing into the input pin and through the protection diode which clamps voltage to Vcc +0.7.
Please tell us which Arduino you're planning to use, and what temp resolution you're expecting.
With the current advice you could be getting less than 0.1C resolution, which is twice as bad as a common/cheap DS18B20. With the Gravity sensor that could be worse.
Expensive sensors, like the one you linked to, deserve an external high resolution absolute A/D, like the ADS1115. Breakout boards with this chip, and a built-in boost converter for sensor power, with I2C output, are available. Like this one.
Leo..
Thank you, everyone, for the help, and sorry for the late response. I have ended up going a different route for the temperature sensor altogether. Wawa, you are 100% right on that sensor choice, especially considering the price. And JCA34F, thank you for the explanation and circuit diagram, that makes a lot more sense seeing it visually. I am sure your circuit would have worked and I am marking it as the answer because that is what I would have done if I went forward with the original plan.
