I am using a thermistor in a wheatstone bridge circuit to measure temperature. I am measruing the voltage across the bridge and then using this value to calculate the resistance of the thermistor and then the temperature.
All the fixed resistors are 10k and the thermistor is 10k (at 25C). When I measure the voltage across the bridge using a multimeter it gives one reading. However, when I use the connect the ADC-40 probem, the voltage drops by approx 0.2V. Obviously the voltage reading is incorrect and subsequently the temperature ends up being wrong.
I am guessing this problem has something to do with the input impedance of the ADC-40 probe (approx 1M?). Is there any way of using the ADC-40 probe to measure the correct voltage (and subsequently temperature) using this circuit (perahps by modifying the circuit or by taking the resistance of the probe into account in the calculation?). Any help would be most appreciated.