In trying to measure a high resistance circuit from 200Kohms - 1 Gohms
tried using a bridge cicuit but the numbers dont come out right unless I keep changing the multiplier.
I was using a 1Mohm reference resister
Thanks
Bob
With such a large reference resistor you will need to have a reasonable settling delay in the measurement instruction. I would try 10-20,000 microseconds for a starter.
I set the settling time as long as possible.
I removed the 1 Mohm and just left the 10K which is part of the TIM.
I can read up to 20Mohm correctly but if I go higher the numbers are incorrect.
I set the settling time as long as possible.
I removed the 1 Mohm and just left the 10K which is part of the TIM.
I can read up to 20Mohm correctly but if I go higher the numbers are incorrect.
I think we would need to see the circuit you are using and program too, but ultimately I think you will be pushing your luck to expect accurate measurements much beyond 20 MOhms.
The reason is that although the differential input impedance of the amplifier is quoted as 20 GOhms, the input current becomes more significant, especially for single-ended measurements. This is quoted at 1nA typical but increases with temperature, i.e. is not constant.