Hi, I'm building a project using an arduino UNO, I have a flex sensor that gives you a variable resistance from 9K? to 30K?. For best precision I need to have the biggest range of voltage drop depending on the sensor's resistance. I'm powering my circuit with arduino's 5V output, and I want to obtain the biggest possible voltage drop when my sensor is at 30K? and the highest voltage when it's at 9K?. It's easy with a potentiometer, but instead of having a variable resistance from 0 to x ? I need to use the sensor. I think I need another parallel resistor, but what would be the best solution to obtain the widest range of voltage ?
Try this: 5V to sensor to Analog pin, 10K from analog pin to Gnd.
Sensor at 9K, Vout = 5 * 10000/(9000+10000) = 2.6V
Sensor at 30K, Vout = 5 * 10000/(30000+10000) = 1.25V
Stick in other values for 10000, if you want.
If you go bigger, need to allow more settling time for the ADC to give accurate readings.
If you go smaller, the resulting range gets smaller.
CrossRoads:
Try this: 5V to sensor to Analog pin, 10K from analog pin to Gnd.Sensor at 9K, Vout = 5 * 10000/(9000+10000) = 2.6V
Sensor at 30K, Vout = 5 * 10000/(30000+10000) = 1.25VStick in other values for 10000, if you want.
If you go bigger, need to allow more settling time for the ADC to give accurate readings.
If you go smaller, the resulting range gets smaller.
With resistances that high and a small output voltage range I'd also add a 0.1uF capacitor between analog pin and GND to help with radio noise.