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Topic: Measuring Kilo to Mega Ohm sensors (Read 693 times) previous topic - next topic

sagi4422

Hello,
I am newbie here and looking for some help in circuit schematics to measure sensors. The baseline resistance of the sensors are 100k-100MOhms and the resistance of the sensors can vary in the same distance, for example, sensor with 10MOhm baseline resistance can exhibit a change up to 90% of its baseline. The readout of the resistance should pass to a computer using Arduino. The working voltage of the sensor is 1V.
Any recommendations for such circuit ?

Thanks.
Sagi

pito

#1
Apr 22, 2013, 09:50 pm Last Edit: Apr 22, 2013, 10:31 pm by pito Reason: 1
You may consider a R->frequency or period converter (with help of a jfet or mosfet op-amp) and do measure the frequency or period with arduino.
See for example below - the period changes from ~1ms (100k) to ~650ms (100Meg). Do measure the period and make some calcs.
Mind the measuring a 100Meg large resistor requires a special construction.. ;)
The voltage on the sensor (Rx) is up to 3.7V (see the fourth picture).

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