hi guys!I want to measure the resistance of a Resistance Temperature Device(RTD) using the analog input of my arduino. Within the temperature range i want to measure the resistance varies from 1700 Ohms to 2300 Ohms. Aditionally i have to restrict the current to 200*10-6 A.Ideally i would like to measure 0V if the resistance of the RTD is 1700 Ohms and 5V at 2300 Ohms.Now my question:What is the advantage of using a wheatstone bridge over a simple voltage divider?
It seems that there is no way of getting around the use of a OA? Is that right?Greetings
if you set Vref to say 0.15 Volts,
Quote from: CaptainJack on May 09, 2013, 06:44 pmNow I'm wondering, if you set Vref to say 0.15 Volts, then you might get all 1024 ADC steps across what you wish to measure.Except with a 0.15 V reference, the largest voltage you could measure would be 0.15 Volts. With those resistor values, the input voltage would range from about 0.36 to 0.47 Volts, both above the range of the reference.A 0.5V reference would work. The analog values should range from about 734 to 969, a span of 235 values.
Now I'm wondering, if you set Vref to say 0.15 Volts, then you might get all 1024 ADC steps across what you wish to measure.
Quoteif you set Vref to say 0.15 Volts, Then you would be working outside the limits of the arduino's A/D which needs a minimum Vref of 1.0V